diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-08 12:50:01 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-12 16:57:57 -0700 |
| commit | ea6f043fc9847e670b91dfbf1ef1cdff3451c152 (patch) | |
| tree | b91a008b262a787388e8bd72a511a9602ff060f8 /arch/x86/lib | |
| parent | 53acd350503d56a73aa6c61bced1699e8396c6d0 (diff) | |
x86: Make __get_user() generate an out-of-line call
Instead of inlining the whole stac/lfence/mov/clac sequence (which also
requires individual exception table entries and several asm instruction
alternatives entries), just generate "call __get_user_nocheck_X" for the
__get_user() cases.
We can use all the same infrastructure that we already do for the
regular "get_user()", and the end result is simpler source code, and
much simpler code generation.
It also means that when I introduce asm goto with input for
"unsafe_get_user()", there are no nasty interactions with the
__get_user() code.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/lib')
| -rw-r--r-- | arch/x86/lib/getuser.S | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S index c8a85b512796..2cd902e06062 100644 --- a/arch/x86/lib/getuser.S +++ b/arch/x86/lib/getuser.S @@ -35,6 +35,8 @@ #include <asm/smap.h> #include <asm/export.h> +#define ASM_BARRIER_NOSPEC ALTERNATIVE "", "lfence", X86_FEATURE_LFENCE_RDTSC + .text SYM_FUNC_START(__get_user_1) mov PER_CPU_VAR(current_task), %_ASM_DX @@ -114,6 +116,52 @@ SYM_FUNC_START(__get_user_8) SYM_FUNC_END(__get_user_8) EXPORT_SYMBOL(__get_user_8) +/* .. and the same for __get_user, just without the range checks */ +SYM_FUNC_START(__get_user_nocheck_1) + ASM_STAC + ASM_BARRIER_NOSPEC +6: movzbl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + ret +SYM_FUNC_END(__get_user_nocheck_1) +EXPORT_SYMBOL(__get_user_nocheck_1) + +SYM_FUNC_START(__get_user_nocheck_2) + ASM_STAC + ASM_BARRIER_NOSPEC +7: movzwl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + ret +SYM_FUNC_END(__get_user_nocheck_2) +EXPORT_SYMBOL(__get_user_nocheck_2) + +SYM_FUNC_START(__get_user_nocheck_4) + ASM_STAC + ASM_BARRIER_NOSPEC +8: movl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + ret +SYM_FUNC_END(__get_user_nocheck_4) +EXPORT_SYMBOL(__get_user_nocheck_4) + +SYM_FUNC_START(__get_user_nocheck_8) + ASM_STAC + ASM_BARRIER_NOSPEC +#ifdef CONFIG_X86_64 +9: movq (%_ASM_AX),%rdx +#else +9: movl (%_ASM_AX),%edx +10: movl 4(%_ASM_AX),%ecx +#endif + xor %eax,%eax + ASM_CLAC + ret +SYM_FUNC_END(__get_user_nocheck_8) +EXPORT_SYMBOL(__get_user_nocheck_8) + SYM_CODE_START_LOCAL(.Lbad_get_user_clac) ASM_CLAC @@ -134,6 +182,7 @@ bad_get_user_8: SYM_CODE_END(.Lbad_get_user_8_clac) #endif +/* get_user */ _ASM_EXTABLE_UA(1b, .Lbad_get_user_clac) _ASM_EXTABLE_UA(2b, .Lbad_get_user_clac) _ASM_EXTABLE_UA(3b, .Lbad_get_user_clac) @@ -143,3 +192,14 @@ SYM_CODE_END(.Lbad_get_user_8_clac) _ASM_EXTABLE_UA(4b, .Lbad_get_user_8_clac) _ASM_EXTABLE_UA(5b, .Lbad_get_user_8_clac) #endif + +/* __get_user */ + _ASM_EXTABLE_UA(6b, .Lbad_get_user_clac) + _ASM_EXTABLE_UA(7b, .Lbad_get_user_clac) + _ASM_EXTABLE_UA(8b, .Lbad_get_user_clac) +#ifdef CONFIG_X86_64 + _ASM_EXTABLE_UA(9b, .Lbad_get_user_clac) +#else + _ASM_EXTABLE_UA(9b, .Lbad_get_user_8_clac) + _ASM_EXTABLE_UA(10b, .Lbad_get_user_8_clac) +#endif |