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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
"The main kernel side changes in this cycle were:
- Various Intel-PT updates and optimizations (Alexander Shishkin)
- Prohibit kprobes on Xen/KVM emulate prefixes (Masami Hiramatsu)
- Add support for LSM and SELinux checks to control access to the
perf syscall (Joel Fernandes)
- Misc other changes, optimizations, fixes and cleanups - see the
shortlog for details.
There were numerous tooling changes as well - 254 non-merge commits.
Here are the main changes - too many to list in detail:
- Enhancements to core tooling infrastructure, perf.data, libperf,
libtraceevent, event parsing, vendor events, Intel PT, callchains,
BPF support and instruction decoding.
- There were updates to the following tools:
perf annotate
perf diff
perf inject
perf kvm
perf list
perf maps
perf parse
perf probe
perf record
perf report
perf script
perf stat
perf test
perf trace
- And a lot of other changes: please see the shortlog and Git log for
more details"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (279 commits)
perf parse: Fix potential memory leak when handling tracepoint errors
perf probe: Fix spelling mistake "addrees" -> "address"
libtraceevent: Fix memory leakage in copy_filter_type
libtraceevent: Fix header installation
perf intel-bts: Does not support AUX area sampling
perf intel-pt: Add support for decoding AUX area samples
perf intel-pt: Add support for recording AUX area samples
perf pmu: When using default config, record which bits of config were changed by the user
perf auxtrace: Add support for queuing AUX area samples
perf session: Add facility to peek at all events
perf auxtrace: Add support for dumping AUX area samples
perf inject: Cut AUX area samples
perf record: Add aux-sample-size config term
perf record: Add support for AUX area sampling
perf auxtrace: Add support for AUX area sample recording
perf auxtrace: Move perf_evsel__find_pmu()
perf record: Add a function to test for kernel support for AUX area sampling
perf tools: Add kernel AUX area sampling definitions
perf/core: Make the mlock accounting simple again
perf report: Jump to symbol source view from total cycles view
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar:
"The main changes in this cycle were:
- Cross-arch changes to move the linker sections for NOTES and
EXCEPTION_TABLE into the RO_DATA area, where they belong on most
architectures. (Kees Cook)
- Switch the x86 linker fill byte from x90 (NOP) to 0xcc (INT3), to
trap jumps into the middle of those padding areas instead of
sliding execution. (Kees Cook)
- A thorough cleanup of symbol definitions within x86 assembler code.
The rather randomly named macros got streamlined around a
(hopefully) straightforward naming scheme:
SYM_START(name, linkage, align...)
SYM_END(name, sym_type)
SYM_FUNC_START(name)
SYM_FUNC_END(name)
SYM_CODE_START(name)
SYM_CODE_END(name)
SYM_DATA_START(name)
SYM_DATA_END(name)
etc - with about three times of these basic primitives with some
label, local symbol or attribute variant, expressed via postfixes.
No change in functionality intended. (Jiri Slaby)
- Misc other changes, cleanups and smaller fixes"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
x86/entry/64: Remove pointless jump in paranoid_exit
x86/entry/32: Remove unused resume_userspace label
x86/build/vdso: Remove meaningless CFLAGS_REMOVE_*.o
m68k: Convert missed RODATA to RO_DATA
x86/vmlinux: Use INT3 instead of NOP for linker fill bytes
x86/mm: Report actual image regions in /proc/iomem
x86/mm: Report which part of kernel image is freed
x86/mm: Remove redundant address-of operators on addresses
xtensa: Move EXCEPTION_TABLE to RO_DATA segment
powerpc: Move EXCEPTION_TABLE to RO_DATA segment
parisc: Move EXCEPTION_TABLE to RO_DATA segment
microblaze: Move EXCEPTION_TABLE to RO_DATA segment
ia64: Move EXCEPTION_TABLE to RO_DATA segment
h8300: Move EXCEPTION_TABLE to RO_DATA segment
c6x: Move EXCEPTION_TABLE to RO_DATA segment
arm64: Move EXCEPTION_TABLE to RO_DATA segment
alpha: Move EXCEPTION_TABLE to RO_DATA segment
x86/vmlinux: Move EXCEPTION_TABLE to RO_DATA segment
x86/vmlinux: Actually use _etext for the end of the text segment
vmlinux.lds.h: Allow EXCEPTION_TABLE to live in RO_DATA
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uaccess regions
The new check_zeroed_user() function uses variable shifts inside of a
user_access_begin()/user_access_end() section and that results in GCC
emitting __ubsan_handle_shift_out_of_bounds() calls, even though
through value range analysis it would be able to see that the UB in
question is impossible.
Annotate and whitelist this UBSAN function; continued use of
user_access_begin()/user_access_end() will undoubtedly result in
further uses of function.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cyphar@cyphar.com
Cc: keescook@chromium.org
Cc: linux@rasmusvillemoes.dk
Fixes: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper")
Link: https://lkml.kernel.org/r/20191021131149.GA19358@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Decode Xen and KVM's emulate-prefix signature by x86 insn decoder.
It is called "prefix" but actually not x86 instruction prefix, so
this adds insn.emulate_prefix_size field instead of reusing
insn.prefixes.
If x86 decoder finds a special sequence of instructions of
XEN_EMULATE_PREFIX and 'ud2a; .ascii "kvm"', it just counts the
length, set insn.emulate_prefix_size and fold it with the next
instruction. In other words, the signature and the next instruction
is treated as a single instruction.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: x86@kernel.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: xen-devel@lists.xenproject.org
Cc: Randy Dunlap <rdunlap@infradead.org>
Link: https://lkml.kernel.org/r/156777564986.25081.4964537658500952557.stgit@devnote2
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Fix the following warning seen on GCC 7.3:
kunit/test-test.o: warning: objtool: kunit_test_unsuccessful_try() falls through to next function kunit_test_catch()
kunit_try_catch_throw is a function added in the following patch in this
series; it allows KUnit, a unit testing framework for the kernel, to
bail out of a broken test. As a consequence, it is a new __noreturn
function that objtool thinks is broken (as seen above). So fix this
warning by adding kunit_try_catch_throw to objtool's noreturn list.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://www.spinics.net/lists/linux-kbuild/msg21708.html
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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Explicitly check kvm_rebooting in kvm_spurious_fault() prior to invoking
BUG(), as opposed to assuming the caller has already done so. Letting
kvm_spurious_fault() be called "directly" will allow VMX to better
optimize its low level assembly flows.
As a happy side effect, kvm_spurious_fault() no longer needs to be
marked as a dead end since it doesn't unconditionally BUG().
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
"Kernel side changes:
- Improved kbprobes robustness
- Intel PEBS support for PT hardware tracing
- Other Intel PT improvements: high order pages memory footprint
reduction and various related cleanups
- Misc cleanups
The perf tooling side has been very busy in this cycle, with over 300
commits. This is an incomplete high-level summary of the many
improvements done by over 30 developers:
- Lots of updates to the following tools:
'perf c2c'
'perf config'
'perf record'
'perf report'
'perf script'
'perf test'
'perf top'
'perf trace'
- Updates to libperf and libtraceevent, and a consolidation of the
proliferation of x86 instruction decoder libraries.
- Vendor event updates for Intel and PowerPC CPUs,
- Updates to hardware tracing tooling for ARM and Intel CPUs,
- ... and lots of other changes and cleanups - see the shortlog and
Git log for details"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (322 commits)
kprobes: Prohibit probing on BUG() and WARN() address
perf/x86: Make more stuff static
x86, perf: Fix the dependency of the x86 insn decoder selftest
objtool: Ignore intentional differences for the x86 insn decoder
objtool: Update sync-check.sh from perf's check-headers.sh
perf build: Ignore intentional differences for the x86 insn decoder
perf intel-pt: Use shared x86 insn decoder
perf intel-pt: Remove inat.c from build dependency list
perf: Update .gitignore file
objtool: Move x86 insn decoder to a common location
perf metricgroup: Support multiple events for metricgroup
perf metricgroup: Scale the metric result
perf pmu: Change convert_scale from static to global
perf symbols: Move mem_info and branch_info out of symbol.h
perf auxtrace: Uninline functions that touch perf_session
perf tools: Remove needless evlist.h include directives
perf tools: Remove needless evlist.h include directives
perf tools: Remove needless thread_map.h include directives
perf tools: Remove needless thread.h include directives
perf tools: Remove needless map.h include directives
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If the build user has the CFLAGS variable set in their environment,
objtool blindly appends to it, which can cause unexpected behavior.
Clobber CFLAGS to ensure consistent objtool compilation behavior.
Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Tested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/83a276df209962e6058fcb6c615eef9d401c21bc.1567121311.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Since we need to build this in !x86, we need to explicitely use the x86
files, not things like asm/insn.h, so we intentionally differ from the
master copy in the kernel sources, add -I diff directives to ignore just
these differences when checking for drift.
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: http://lore.kernel.org/lkml/20190830193109.p7jagidsrahoa4pn@treble
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/n/tip-j965m9b7xtdc83em3twfkh9o@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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To allow using the -I trick that will be needed for checking the x86
insn decoder files.
Without the specific -I lines we still get the same warnings as before:
$ make -C tools/objtool/ clean ; make -C tools/objtool/
make: Entering directory '/home/acme/git/perf/tools/objtool'
CLEAN objtool
find -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
rm -f arch/x86/inat-tables.c fixdep
<SNIP>
LD objtool-in.o
make[1]: Leaving directory '/home/acme/git/perf/tools/objtool'
Warning: Kernel ABI header at 'tools/arch/x86/include/asm/inat.h' differs from latest version at 'arch/x86/include/asm/inat.h'
diff -u tools/arch/x86/include/asm/inat.h arch/x86/include/asm/inat.h
Warning: Kernel ABI header at 'tools/arch/x86/include/asm/insn.h' differs from latest version at 'arch/x86/include/asm/insn.h'
diff -u tools/arch/x86/include/asm/insn.h arch/x86/include/asm/insn.h
Warning: Kernel ABI header at 'tools/arch/x86/lib/inat.c' differs from latest version at 'arch/x86/lib/inat.c'
diff -u tools/arch/x86/lib/inat.c arch/x86/lib/inat.c
Warning: Kernel ABI header at 'tools/arch/x86/lib/insn.c' differs from latest version at 'arch/x86/lib/insn.c'
diff -u tools/arch/x86/lib/insn.c arch/x86/lib/insn.c
/home/acme/git/perf/tools/objtool
LINK objtool
make: Leaving directory '/home/acme/git/perf/tools/objtool'
$
The next patch will add the -I lines for those files.
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: http://lore.kernel.org/lkml/20190830193109.p7jagidsrahoa4pn@treble
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/n/tip-vu3p38mnxlwd80rlsnjkqcf2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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The kernel tree has three identical copies of the x86 instruction
decoder. Two of them are in the tools subdir.
The tools subdir is supposed to be completely standalone and separate
from the kernel. So having at least one copy of the kernel decoder in
the tools subdir is unavoidable. However, we don't need *two* of them.
Move objtool's copy of the decoder to a shared location, so that perf
will also be able to use it.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: x86@kernel.org
Link: http://lore.kernel.org/lkml/55b486b88f6bcd0c9a2a04b34f964860c8390ca8.1567118001.git.jpoimboe@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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A clang build reported an (obvious) double CLAC while a GCC build did not;
it turns out that objtool only re-visits instructions if the first visit
was with AC=0. If OTOH the first visit was with AC=1, it completely ignores
any subsequent visit, even when it has AC=0.
Fix this by using a visited mask instead of a boolean, and (explicitly)
mark the AC state.
$ ./objtool check -b --no-fp --retpoline --uaccess drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x22: redundant UACCESS disable
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xea: (alt)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xd9: (alt)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xb2: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x39: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x0: <=== (func)
Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/617
Link: https://lkml.kernel.org/r/5359166aad2d53f3145cd442d83d0e5115e0cd17.1564007838.git.jpoimboe@redhat.com
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A Clang-built kernel is showing the following warning:
arch/x86/kernel/platform-quirks.o: warning: objtool: x86_early_init_platform_quirks()+0x84: unreachable instruction
That corresponds to this code:
7e: 0f 85 00 00 00 00 jne 84 <x86_early_init_platform_quirks+0x84>
80: R_X86_64_PC32 __x86_indirect_thunk_r11-0x4
84: c3 retq
This is a conditional retpoline sibling call, which is now possible
thanks to retpolines. Objtool hasn't seen that before. It's
incorrectly interpreting the conditional jump as an unconditional
dynamic jump.
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/30d4c758b267ef487fb97e6ecb2f148ad007b554.1563413318.git.jpoimboe@redhat.com
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This makes it easier to add new instruction types. Also it's hopefully
more robust since the compiler should warn about out-of-range enums.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/0740e96af0d40e54cfd6a07bf09db0fbd10793cd.1563413318.git.jpoimboe@redhat.com
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In one rare case, Clang generated the following code:
5ca: 83 e0 21 and $0x21,%eax
5cd: b9 04 00 00 00 mov $0x4,%ecx
5d2: ff 24 c5 00 00 00 00 jmpq *0x0(,%rax,8)
5d5: R_X86_64_32S .rodata+0x38
which uses the corresponding jump table relocations:
000000000038 000200000001 R_X86_64_64 0000000000000000 .text + 834
000000000040 000200000001 R_X86_64_64 0000000000000000 .text + 5d9
000000000048 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000050 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000058 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000060 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000068 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000070 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000078 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000080 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000088 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000090 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000098 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000a0 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000a8 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000b0 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000b8 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000c0 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000c8 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000d0 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000d8 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000e0 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000e8 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000f0 000200000001 R_X86_64_64 0000000000000000 .text + b96
0000000000f8 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000100 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000108 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000110 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000118 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000120 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000128 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000130 000200000001 R_X86_64_64 0000000000000000 .text + b96
000000000138 000200000001 R_X86_64_64 0000000000000000 .text + 82f
000000000140 000200000001 R_X86_64_64 0000000000000000 .text + 828
Since %eax was masked with 0x21, only the first two and the last two
entries are possible.
Objtool doesn't actually emulate all the code, so it isn't smart enough
to know that all the middle entries aren't reachable. They point to the
NOP padding area after the end of the function, so objtool seg faulted
when it tried to dereference a NULL insn->func.
After this fix, objtool still gives an "unreachable" error because it
stops reading the jump table when it encounters the bad addresses:
/home/jpoimboe/objtool-tests/adm1275.o: warning: objtool: adm1275_probe()+0x828: unreachable instruction
While the above code is technically correct, it's very wasteful of
memory -- it uses 34 jump table entries when only 4 are needed. It's
also not possible for objtool to validate this type of switch table
because the unused entries point outside the function and objtool has no
way of determining if that's intentional. Hopefully the Clang folks can
fix it.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/a9db88eec4f1ca089e040989846961748238b6d8.1563413318.git.jpoimboe@redhat.com
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This fixes objtool for both a GCC issue and a Clang issue:
1) GCC issue:
kernel/bpf/core.o: warning: objtool: ___bpf_prog_run()+0x8d5: sibling call from callable instruction with modified stack frame
With CONFIG_RETPOLINE=n, GCC is doing the following optimization in
___bpf_prog_run().
Before:
select_insn:
jmp *jumptable(,%rax,8)
...
ALU64_ADD_X:
...
jmp select_insn
ALU_ADD_X:
...
jmp select_insn
After:
select_insn:
jmp *jumptable(, %rax, 8)
...
ALU64_ADD_X:
...
jmp *jumptable(, %rax, 8)
ALU_ADD_X:
...
jmp *jumptable(, %rax, 8)
This confuses objtool. It has never seen multiple indirect jump
sites which use the same jump table.
For GCC switch tables, the only way of detecting the size of a table
is by continuing to scan for more tables. The size of the previous
table can only be determined after another switch table is found, or
when the scan reaches the end of the function.
That logic was reused for C jump tables, and was based on the
assumption that each jump table only has a single jump site. The
above optimization breaks that assumption.
2) Clang issue:
drivers/usb/misc/sisusbvga/sisusb.o: warning: objtool: sisusb_write_mem_bulk()+0x588: can't find switch jump table
With clang 9, code can be generated where a function contains two
indirect jump instructions which use the same switch table.
The fix is the same for both issues: split the jump table parsing into
two passes.
In the first pass, locate the heads of all switch tables for the
function and mark their locations.
In the second pass, parse the switch tables and add them.
Fixes: e55a73251da3 ("bpf: Fix ORC unwinding in non-JIT BPF code")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/e995befaada9d4d8b2cf788ff3f566ba900d2b4d.1563413318.git.jpoimboe@redhat.com
Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
|
|
Now that C jump tables are supported, call them "jump tables" instead of
"switch tables". Also rename some other variables, add comments, and
simplify the code flow a bit.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/cf951b0c0641628e0b9b81f7ceccd9bcabcb4bd8.1563413318.git.jpoimboe@redhat.com
|
|
Simplify the sibling call detection logic a bit.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/8357dbef9e7f5512e76bf83a76c81722fc09eb5e.1563413318.git.jpoimboe@redhat.com
|
|
Even calls to __noreturn functions need the frame pointer setup first.
Such functions often dump the stack.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/aed62fbd60e239280218be623f751a433658e896.1563413318.git.jpoimboe@redhat.com
|
|
dead_end_function() can no longer return an error. Simplify its
interface by making it return boolean.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/9e6679610768fb6e6c51dca23f7d4d0c03b0c910.1563413318.git.jpoimboe@redhat.com
|
|
All callable functions should have an ELF size.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/03d429c4fa87829c61c5dc0e89652f4d9efb62f1.1563413318.git.jpoimboe@redhat.com
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- Add an alias check in validate_functions(). With this change, aliases
no longer need uaccess_safe set.
- Add an alias check in decode_instructions(). With this change, the
"if (!insn->func)" check is no longer needed.
- Don't create aliases for zero-length functions, as it can have
unexpected results. The next patch will spit out a warning for
zero-length functions anyway.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/26a99c31426540f19c9a58b9e10727c385a147bc.1563413318.git.jpoimboe@redhat.com
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If 'insn->func' is NULL, objtool skips some important checks, including
sibling call validation. So if some .fixup code does an invalid sibling
call, objtool ignores it.
Treat all code branches (including alts) as part of the original
function by keeping track of the original func value from
validate_functions().
This improves the usefulness of some clang function fallthrough
warnings, and exposes some additional kernel bugs in the process.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/505df630f33c9717e1ccde6e4b64c5303135c25f.1563413318.git.jpoimboe@redhat.com
|
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After an objtool improvement, it's reporting that __memcpy_mcsafe() is
calling mcsafe_handle_tail() with AC=1:
arch/x86/lib/memcpy_64.o: warning: objtool: .fixup+0x13: call to mcsafe_handle_tail() with UACCESS enabled
arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0x34: (alt)
arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0xb: (branch)
arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0x0: <=== (func)
mcsafe_handle_tail() is basically an extension of __memcpy_mcsafe(), so
AC=1 is supposed to be set. Add mcsafe_handle_tail() to the uaccess
safe list.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/035c38f7eac845281d3c3d36749144982e06e58c.1563413318.git.jpoimboe@redhat.com
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Pick up the two pending objtool patches as the next round of objtool fixes
depend on them.
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The elftoolchain version of libelf has a function named elf_open().
The function name isn't quite accurate anyway, since it also reads all
the ELF data. Rename it to elf_read(), which is more accurate.
[ jpoimboe: rename to elf_read(); write commit description ]
Signed-off-by: Michael Forney <mforney@mforney.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/7ce2d1b35665edf19fd0eb6fbc0b17b81a48e62f.1562793604.git.jpoimboe@redhat.com
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The libelf implementation might use a different struct name, and the
Elf_Scn typedef is already used throughout the rest of objtool.
Signed-off-by: Michael Forney <mforney@mforney.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/d270e1be2835fc2a10acf67535ff2ebd2145bf43.1562793448.git.jpoimboe@redhat.com
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Pull Documentation updates from Jonathan Corbet:
"It's been a relatively busy cycle for docs:
- A fair pile of RST conversions, many from Mauro. These create more
than the usual number of simple but annoying merge conflicts with
other trees, unfortunately. He has a lot more of these waiting on
the wings that, I think, will go to you directly later on.
- A new document on how to use merges and rebases in kernel repos,
and one on Spectre vulnerabilities.
- Various improvements to the build system, including automatic
markup of function() references because some people, for reasons I
will never understand, were of the opinion that
:c:func:``function()`` is unattractive and not fun to type.
- We now recommend using sphinx 1.7, but still support back to 1.4.
- Lots of smaller improvements, warning fixes, typo fixes, etc"
* tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits)
docs: automarkup.py: ignore exceptions when seeking for xrefs
docs: Move binderfs to admin-guide
Disable Sphinx SmartyPants in HTML output
doc: RCU callback locks need only _bh, not necessarily _irq
docs: format kernel-parameters -- as code
Doc : doc-guide : Fix a typo
platform: x86: get rid of a non-existent document
Add the RCU docs to the core-api manual
Documentation: RCU: Add TOC tree hooks
Documentation: RCU: Rename txt files to rst
Documentation: RCU: Convert RCU UP systems to reST
Documentation: RCU: Convert RCU linked list to reST
Documentation: RCU: Convert RCU basic concepts to reST
docs: filesystems: Remove uneeded .rst extension on toctables
scripts/sphinx-pre-install: fix out-of-tree build
docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/
Documentation: PGP: update for newer HW devices
Documentation: Add section about CPU vulnerabilities for Spectre
Documentation: platform: Delete x86-laptop-drivers.txt
docs: Note that :c:func: should no longer be used
...
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Objtool doesn't know how to read C jump tables, so it has to whitelist
functions which use them, causing missing ORC unwinder data for such
functions, e.g. ___bpf_prog_run().
C jump tables are very similar to GCC switch jump tables, which objtool
already knows how to read. So adding support for C jump tables is easy.
It just needs to be able to find the tables and distinguish them from
other data.
To allow the jump tables to be found, create an __annotate_jump_table
macro which can be used to annotate them.
The annotation is done by placing the jump table in an
.rodata..c_jump_table section. The '.rodata' prefix ensures that the data
will be placed in the rodata section by the vmlinux linker script. The
double periods are part of an existing convention which distinguishes
kernel sections from GCC sections.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Kairui Song <kasong@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lkml.kernel.org/r/0ba2ca30442b16b97165992381ce643dc27b3d1a.1561685471.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Fix objtool build, because it adds _ctype dependency via isspace call patch.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: André Goddard Rosa <andre.goddard@gmail.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 7bd330de43fd ("tools lib: Adopt skip_spaces() from the kernel sources")
Link: http://lkml.kernel.org/r/20190702121240.GB12694@krava
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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We need to pick up post-rc1 changes to various document files so they don't
get lost in Mauro's massive RST conversion push.
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Mostly due to x86 and acpi conversion, several documentation
links are still pointing to the old file. Fix them.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 1334 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not see http www gnu org licenses
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details [based]
[from] [clk] [highbank] [c] you should have received a copy of the
gnu general public license along with this program if not see http
www gnu org licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 355 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core fixes from Ingo Molnar:
"This fixes a particularly thorny munmap() bug with MPX, plus fixes a
host build environment assumption in objtool"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Allow AR to be overridden with HOSTAR
x86/mpx, mm/core: Fix recursive munmap() corruption
|
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Currently, this Makefile hardcodes GNU ar, meaning that if it is not
available, there is no way to supply a different one and the build will
fail.
$ make AR=llvm-ar CC=clang LD=ld.lld HOSTAR=llvm-ar HOSTCC=clang \
HOSTLD=ld.lld HOSTLDFLAGS=-fuse-ld=lld defconfig modules_prepare
...
AR /out/tools/objtool/libsubcmd.a
/bin/sh: 1: ar: not found
...
Follow the logic of HOST{CC,LD} and allow the user to specify a
different ar tool via HOSTAR (which is used elsewhere in other
tools/ Makefiles).
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/80822a9353926c38fd7a152991c6292491a9d0e8.1558028966.git.jpoimboe@redhat.com
Link: https://github.com/ClangBuiltLinux/linux/issues/481
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core fixes from Ingo Molnar:
"A handful of objtool updates, plus a documentation addition for
__ab_c_size()"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix whitelist documentation typo
objtool: Fix function fallthrough detection
objtool: Don't use ignore flag for fake jumps
overflow.h: Add comment documenting __ab_c_size()
|
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The directive specified in the documentation to add an exception
for a single file in a Makefile was inverted.
Signed-off-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/522362a1b934ee39d0af0abb231f68e160ecf1a8.1557874043.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
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When a function falls through to the next function due to a compiler
bug, objtool prints some obscure warnings. For example:
drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x95: return with modified stack frame
drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x0: stack state mismatch: cfa1=7+32 cfa2=7+8
Instead it should be printing:
drivers/regulator/core.o: warning: objtool: regulator_supply_is_couple() falls through to next function regulator_count_voltages()
This used to work, but was broken by the following commit:
13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")
The padding nops at the end of a function aren't actually part of the
function, as defined by the symbol table. So the 'func' variable in
validate_branch() is getting cleared to NULL when a padding nop is
encountered, breaking the fallthrough detection.
If the current instruction doesn't have a function associated with it,
just consider it to be part of the previously detected function by not
overwriting the previous value of 'func'.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")
Link: http://lkml.kernel.org/r/546d143820cd08a46624ae8440d093dd6c902cae.1557766718.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
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The ignore flag is set on fake jumps in order to keep
add_jump_destinations() from setting their jump_dest, since it already
got set when the fake jump was created.
But using the ignore flag is a bit of a hack. It's normally used to
skip validation of an instruction, which doesn't really make sense for
fake jumps.
Also, after the next patch, using the ignore flag for fake jumps can
trigger a false "why am I validating an ignored function?" warning.
Instead just add an explicit check in add_jump_destinations() to skip
fake jumps.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/71abc072ff48b2feccc197723a9c52859476c068.1557766718.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
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Pull documentation updates from Jonathan Corbet:
"A reasonably busy cycle for docs, including:
- Lots of work on the Chinese and Italian translations
- Some license-rules clarifications from Christoph
- Various build-script fixes
- A new document on memory models
- RST conversion of the live-patching docs
- The usual collection of typo fixes and corrections"
* tag 'docs-5.2' of git://git.lwn.net/linux: (140 commits)
docs/livepatch: Unify style of livepatch documentation in the ReST format
docs: livepatch: convert docs to ReST and rename to *.rst
scripts/documentation-file-ref-check: detect broken :doc:`foo`
scripts/documentation-file-ref-check: don't parse Next/ dir
LICENSES: Rename other to deprecated
LICENSES: Clearly mark dual license only licenses
docs: Don't reference the ZLib license in license-rules.rst
docs/vm: Minor editorial changes in the THP and hugetlbfs
docs/vm: add documentation of memory models
doc:it_IT: translation alignment
doc: fix typo in PGP guide
dontdiff: update with Kconfig build artifacts
docs/zh_CN: fix typos in 1.Intro.rst file
docs/zh_CN: redirect CoC docs to Chinese version
doc: mm: migration doesn't use FOLL_SPLIT anymore
docs: doc-guide: remove the extension from .rst files
doc: kselftest: Fix KBUILD_OUTPUT usage instructions
docs: trace: fix some Sphinx warnings
docs: speculation.txt: mark example blocks as such
docs: ntb.txt: add blank lines to clean up some Sphinx warnings
...
|
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Convert livepatch documentation to ReST format. The changes
are mostly trivial, as the documents are already on a good
shape. Just a few markup changes are needed for Sphinx to
properly parse the docs.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- The in-file TOC becomes a comment, in order to skip it from the
output, as Sphinx already generates an index there.
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
|
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
"This is a series from Peter Zijlstra that adds x86 build-time uaccess
validation of SMAP to objtool, which will detect and warn about the
following uaccess API usage bugs and weirdnesses:
- call to %s() with UACCESS enabled
- return with UACCESS enabled
- return with UACCESS disabled from a UACCESS-safe function
- recursive UACCESS enable
- redundant UACCESS disable
- UACCESS-safe disables UACCESS
As it turns out not leaking uaccess permissions outside the intended
uaccess functionality is hard when the interfaces are complex and when
such bugs are mostly dormant.
As a bonus we now also check the DF flag. We had at least one
high-profile bug in that area in the early days of Linux, and the
checking is fairly simple. The checks performed and warnings emitted
are:
- call to %s() with DF set
- return with DF set
- return with modified stack frame
- recursive STD
- redundant CLD
It's all x86-only for now, but later on this can also be used for PAN
on ARM and objtool is fairly cross-platform in principle.
While all warnings emitted by this new checking facility that got
reported to us were fixed, there might be GCC version dependent
warnings that were not reported yet - which we'll address, should they
trigger.
The warnings are non-fatal build warnings"
* 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions
x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation
sched/x86_64: Don't save flags on context switch
objtool: Add Direction Flag validation
objtool: Add UACCESS validation
objtool: Fix sibling call detection
objtool: Rewrite alt->skip_orig
objtool: Add --backtrace support
objtool: Rewrite add_ignores()
objtool: Handle function aliases
objtool: Set insn->func for alternatives
x86/uaccess, kcov: Disable stack protector
x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP
x86/uaccess, ubsan: Fix UBSAN vs. SMAP
x86/uaccess, kasan: Fix KASAN vs SMAP
x86/smap: Ditch __stringify()
x86/uaccess: Introduce user_access_{save,restore}()
x86/uaccess, signal: Fix AC=1 bloat
x86/uaccess: Always inline user_access_begin()
x86/uaccess, xen: Suppress SMAP warnings
...
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This fixes the following warning seen on GCC 7.3:
arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_regs()
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/3418ebf5a5a9f6ed7e80954c741c0b904b67b5dc.1554398240.git.jpoimboe@redhat.com
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Having DF escape is BAD(tm).
Linus; you suggested this one, but since DF really is only used from
ASM and the failure case is fairly obvious, do we really need this?
OTOH the patch is fairly small and simple, so let's just do this
to demonstrate objtool's superior awesomeness.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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It is important that UACCESS regions are as small as possible;
furthermore the UACCESS state is not scheduled, so doing anything that
might directly call into the scheduler will cause random code to be
ran with UACCESS enabled.
Teach objtool too track UACCESS state and warn about any CALL made
while UACCESS is enabled. This very much includes the __fentry__()
and __preempt_schedule() calls.
Note that exceptions _do_ save/restore the UACCESS state, and therefore
they can drive preemption. This also means that all exception handlers
must have an otherwise redundant UACCESS disable instruction;
therefore ignore this warning for !STT_FUNC code (exception handlers
are not normal functions).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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It turned out that we failed to detect some sibling calls;
specifically those without relocation records; like:
$ ./objdump-func.sh defconfig-build/mm/kasan/generic.o __asan_loadN
0000 0000000000000840 <__asan_loadN>:
0000 840: 48 8b 0c 24 mov (%rsp),%rcx
0004 844: 31 d2 xor %edx,%edx
0006 846: e9 45 fe ff ff jmpq 690 <check_memory_region>
So extend the cross-function jump to also consider those that are not
between known (or newly detected) parent/child functions, as
sibling-cals when they jump to the start of the function.
The second part of that condition is to deal with random jumps to the
middle of other function, as can be found in
arch/x86/lib/copy_user_64.S for example.
This then (with later patches applied) makes the above recognise the
sibling call:
mm/kasan/generic.o: warning: objtool: __asan_loadN()+0x6: call to check_memory_region() with UACCESS enabled
Also make sure to set insn->call_dest for sibling calls so we can know
who we're calling. This is useful information when printing validation
warnings later.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Really skip the original instruction flow, instead of letting it
continue with NOPs.
Since the alternative code flow already continues after the original
instructions, only the alt-original is skipped.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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For when you want to know the path that reached your fail state:
$ ./objtool check --no-fp --backtrace arch/x86/lib/usercopy_64.o
arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x3: UACCESS disable without MEMOPs: __clear_user()
arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x3a: (alt)
arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x2e: (branch)
arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x18: (branch)
arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch)
arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x5: (alt)
arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x0: <=== (func)
0000000000000000 <__clear_user>:
0: e8 00 00 00 00 callq 5 <__clear_user+0x5>
1: R_X86_64_PLT32 __fentry__-0x4
5: 90 nop
6: 90 nop
7: 90 nop
8: 48 89 f0 mov %rsi,%rax
b: 48 c1 ee 03 shr $0x3,%rsi
f: 83 e0 07 and $0x7,%eax
12: 48 89 f1 mov %rsi,%rcx
15: 48 85 c9 test %rcx,%rcx
18: 74 0f je 29 <__clear_user+0x29>
1a: 48 c7 07 00 00 00 00 movq $0x0,(%rdi)
21: 48 83 c7 08 add $0x8,%rdi
25: ff c9 dec %ecx
27: 75 f1 jne 1a <__clear_user+0x1a>
29: 48 89 c1 mov %rax,%rcx
2c: 85 c9 test %ecx,%ecx
2e: 74 0a je 3a <__clear_user+0x3a>
30: c6 07 00 movb $0x0,(%rdi)
33: 48 ff c7 inc %rdi
36: ff c9 dec %ecx
38: 75 f6 jne 30 <__clear_user+0x30>
3a: 90 nop
3b: 90 nop
3c: 90 nop
3d: 48 89 c8 mov %rcx,%rax
40: c3 retq
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The whole add_ignores() thing was wildly weird; rewrite it according
to 'modern' ways.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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