From 2e549b2ee0e358bc758480e716b881f9cabedb6a Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 16 Aug 2018 12:41:15 -0700 Subject: x86/vdso: Fix vDSO build if a retpoline is emitted Currently, if the vDSO ends up containing an indirect branch or call, GCC will emit the "external thunk" style of retpoline, and it will fail to link. Fix it by building the vDSO with inline retpoline thunks. I haven't seen any reports of this triggering on an unpatched kernel. Fixes: commit 76b043848fd2 ("x86/retpoline: Add initial retpoline support") Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Acked-by: Matt Rickard Cc: Borislav Petkov Cc: Jason Vas Dias Cc: David Woodhouse Cc: Peter Zijlstra Cc: Andi Kleen Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org --- arch/x86/entry/vdso/Makefile | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 9f695f517747..fa3f439f0a92 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -68,9 +68,9 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \ $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \ -fno-omit-frame-pointer -foptimize-sibling-calls \ - -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO + -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO $(RETPOLINE_VDSO_CFLAGS) -$(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) +$(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) # # vDSO code runs in userspace and -pg doesn't help with profiling anyway. @@ -132,11 +132,13 @@ KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic KBUILD_CFLAGS_32 += $(call cc-option, -fno-stack-protector) KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls) KBUILD_CFLAGS_32 += -fno-omit-frame-pointer KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING +KBUILD_CFLAGS_32 += $(RETPOLINE_VDSO_CFLAGS) $(obj)/vdso32.so.dbg: KBUILD_CFLAGS = $(KBUILD_CFLAGS_32) $(obj)/vdso32.so.dbg: FORCE \ -- cgit v1.2.3-58-ga151 From 704ae091b061082b37a9968621af4c290c641d50 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 17 Aug 2018 12:01:36 +0200 Subject: x86/mce: Add notifier_block forward declaration Without linux/irq.h, there is no declaration of notifier_block, leading to a build warning: In file included from arch/x86/kernel/cpu/mcheck/threshold.c:10: arch/x86/include/asm/mce.h:151:46: error: 'struct notifier_block' declared inside parameter list will not be visible outside of this definition or declaration [-Werror] It's sufficient to declare the struct tag here, which avoids pulling in more header files. Fixes: 447ae3166702 ("x86: Don't include linux/irq.h from asm/hardirq.h") Signed-off-by: Arnd Bergmann Signed-off-by: Thomas Gleixner Cc: Nicolai Stange Cc: "H. Peter Anvin" Cc: Greg Kroah-Hartman Cc: Borislav Petkov Link: https://lkml.kernel.org/r/20180817100156.3009043-1-arnd@arndb.de --- arch/x86/include/asm/mce.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch') diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h index 8c7b3e5a2d01..3a17107594c8 100644 --- a/arch/x86/include/asm/mce.h +++ b/arch/x86/include/asm/mce.h @@ -148,6 +148,7 @@ enum mce_notifier_prios { MCE_PRIO_LOWEST = 0, }; +struct notifier_block; extern void mce_register_decode_chain(struct notifier_block *nb); extern void mce_unregister_decode_chain(struct notifier_block *nb); -- cgit v1.2.3-58-ga151 From dc76803e57cc86589c4efcb5362918f9b0c0436f Mon Sep 17 00:00:00 2001 From: Rian Hunter Date: Sun, 19 Aug 2018 16:08:53 -0700 Subject: x86/process: Re-export start_thread() The consolidation of the start_thread() functions removed the export unintentionally. This breaks binfmt handlers built as a module. Add it back. Fixes: e634d8fc792c ("x86-64: merge the standard and compat start_thread() functions") Signed-off-by: Rian Hunter Signed-off-by: Thomas Gleixner Cc: "H. Peter Anvin" Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Vitaly Kuznetsov Cc: Joerg Roedel Cc: Dmitry Safonov Cc: Josh Poimboeuf Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180819230854.7275-1-rian@alum.mit.edu --- arch/x86/kernel/process_64.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch') diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 476e3ddf8890..a451bc374b9b 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -384,6 +384,7 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) start_thread_common(regs, new_ip, new_sp, __USER_CS, __USER_DS, 0); } +EXPORT_SYMBOL_GPL(start_thread); #ifdef CONFIG_COMPAT void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp) -- cgit v1.2.3-58-ga151 From 9df9516940a61d29aedf4d91b483ca6597e7d480 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Mon, 20 Aug 2018 11:58:35 +0200 Subject: x86/speculation/l1tf: Fix overflow in l1tf_pfn_limit() on 32bit On 32bit PAE kernels on 64bit hardware with enough physical bits, l1tf_pfn_limit() will overflow unsigned long. This in turn affects max_swapfile_size() and can lead to swapon returning -EINVAL. This has been observed in a 32bit guest with 42 bits physical address size, where max_swapfile_size() overflows exactly to 1 << 32, thus zero, and produces the following warning to dmesg: [ 6.396845] Truncating oversized swap area, only using 0k out of 2047996k Fix this by using unsigned long long instead. Fixes: 17dbca119312 ("x86/speculation/l1tf: Add sysfs reporting for l1tf") Fixes: 377eeaa8e11f ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2") Reported-by: Dominique Leuenberger Reported-by: Adrian Schroeter Signed-off-by: Vlastimil Babka Signed-off-by: Thomas Gleixner Acked-by: Andi Kleen Acked-by: Michal Hocko Cc: "H . Peter Anvin" Cc: Linus Torvalds Cc: Dave Hansen Cc: Michal Hocko Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180820095835.5298-1-vbabka@suse.cz --- arch/x86/include/asm/processor.h | 4 ++-- arch/x86/mm/init.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 682286aca881..a0a52274cb4a 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -181,9 +181,9 @@ extern const struct seq_operations cpuinfo_op; extern void cpu_detect(struct cpuinfo_x86 *c); -static inline unsigned long l1tf_pfn_limit(void) +static inline unsigned long long l1tf_pfn_limit(void) { - return BIT(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1; + return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1; } extern void early_cpu_init(void); diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index acfab322fbe0..02de3d6065c4 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -923,7 +923,7 @@ unsigned long max_swapfile_size(void) if (boot_cpu_has_bug(X86_BUG_L1TF)) { /* Limit the swap file size to MAX_PA/2 for L1TF workaround */ - unsigned long l1tf_limit = l1tf_pfn_limit() + 1; + unsigned long long l1tf_limit = l1tf_pfn_limit() + 1; /* * We encode swap offsets also with 3 bits below those for pfn * which makes the usable limit higher. @@ -931,7 +931,7 @@ unsigned long max_swapfile_size(void) #if CONFIG_PGTABLE_LEVELS > 2 l1tf_limit <<= PAGE_SHIFT - SWP_OFFSET_FIRST_BIT; #endif - pages = min_t(unsigned long, l1tf_limit, pages); + pages = min_t(unsigned long long, l1tf_limit, pages); } return pages; } -- cgit v1.2.3-58-ga151 From 94d7a86c21a3d6046bf4616272313cb7d525075a Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 14 Aug 2018 12:32:19 -0500 Subject: x86/kvm/vmx: Remove duplicate l1d flush definitions These are already defined higher up in the file. Fixes: 7db92e165ac8 ("x86/kvm: Move l1tf setup function") Signed-off-by: Josh Poimboeuf Signed-off-by: Thomas Gleixner Cc: Paolo Bonzini Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/d7ca03ae210d07173452aeed85ffe344301219a5.1534253536.git.jpoimboe@redhat.com --- arch/x86/kvm/vmx.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 46b428c0990e..4be481c72f60 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -9726,9 +9726,6 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) * information but as all relevant affected CPUs have 32KiB L1D cache size * there is no point in doing so. */ -#define L1D_CACHE_ORDER 4 -static void *vmx_l1d_flush_pages; - static void vmx_l1d_flush(struct kvm_vcpu *vcpu) { int size = PAGE_SIZE << L1D_CACHE_ORDER; -- cgit v1.2.3-58-ga151 From b0a182f875689647b014bc01d36b340217792852 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Thu, 23 Aug 2018 15:44:18 +0200 Subject: x86/speculation/l1tf: Fix off-by-one error when warning that system has too much RAM Two users have reported [1] that they have an "extremely unlikely" system with more than MAX_PA/2 memory and L1TF mitigation is not effective. In fact it's a CPU with 36bits phys limit (64GB) and 32GB memory, but due to holes in the e820 map, the main region is almost 500MB over the 32GB limit: [ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000081effffff] usable Suggestions to use 'mem=32G' to enable the L1TF mitigation while losing the 500MB revealed, that there's an off-by-one error in the check in l1tf_select_mitigation(). l1tf_pfn_limit() returns the last usable pfn (inclusive) and the range check in the mitigation path does not take this into account. Instead of amending the range check, make l1tf_pfn_limit() return the first PFN which is over the limit which is less error prone. Adjust the other users accordingly. [1] https://bugzilla.suse.com/show_bug.cgi?id=1105536 Fixes: 17dbca119312 ("x86/speculation/l1tf: Add sysfs reporting for l1tf") Reported-by: George Anchev Reported-by: Christopher Snowhill Signed-off-by: Vlastimil Babka Signed-off-by: Thomas Gleixner Cc: "H . Peter Anvin" Cc: Linus Torvalds Cc: Andi Kleen Cc: Dave Hansen Cc: Michal Hocko Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180823134418.17008-1-vbabka@suse.cz --- arch/x86/include/asm/processor.h | 2 +- arch/x86/mm/init.c | 2 +- arch/x86/mm/mmap.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) (limited to 'arch') diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index a0a52274cb4a..c24297268ebc 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -183,7 +183,7 @@ extern void cpu_detect(struct cpuinfo_x86 *c); static inline unsigned long long l1tf_pfn_limit(void) { - return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1; + return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT); } extern void early_cpu_init(void); diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 02de3d6065c4..63a6f9fcaf20 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -923,7 +923,7 @@ unsigned long max_swapfile_size(void) if (boot_cpu_has_bug(X86_BUG_L1TF)) { /* Limit the swap file size to MAX_PA/2 for L1TF workaround */ - unsigned long long l1tf_limit = l1tf_pfn_limit() + 1; + unsigned long long l1tf_limit = l1tf_pfn_limit(); /* * We encode swap offsets also with 3 bits below those for pfn * which makes the usable limit higher. diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index f40ab8185d94..1e95d57760cf 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -257,7 +257,7 @@ bool pfn_modify_allowed(unsigned long pfn, pgprot_t prot) /* If it's real memory always allow */ if (pfn_valid(pfn)) return true; - if (pfn > l1tf_pfn_limit() && !capable(CAP_SYS_ADMIN)) + if (pfn >= l1tf_pfn_limit() && !capable(CAP_SYS_ADMIN)) return false; return true; } -- cgit v1.2.3-58-ga151 From 6a012288d6906fee1dbc244050ade1dafe4a9c8d Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Thu, 23 Aug 2018 16:21:29 +0200 Subject: x86/speculation/l1tf: Suggest what to do on systems with too much RAM Two users have reported [1] that they have an "extremely unlikely" system with more than MAX_PA/2 memory and L1TF mitigation is not effective. Make the warning more helpful by suggesting the proper mem=X kernel boot parameter to make it effective and a link to the L1TF document to help decide if the mitigation is worth the unusable RAM. [1] https://bugzilla.suse.com/show_bug.cgi?id=1105536 Suggested-by: Michal Hocko Signed-off-by: Vlastimil Babka Acked-by: Michal Hocko Cc: "H . Peter Anvin" Cc: Linus Torvalds Cc: Andi Kleen Cc: Dave Hansen Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/966571f0-9d7f-43dc-92c6-a10eec7a1254@suse.cz --- arch/x86/kernel/cpu/bugs.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch') diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index cb4a16292aa7..4c2313d0b9ca 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -702,6 +702,10 @@ static void __init l1tf_select_mitigation(void) half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT; if (e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) { pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n"); + pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n", + half_pa); + pr_info("However, doing so will make a part of your RAM unusable.\n"); + pr_info("Reading https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html might help you decide.\n"); return; } -- cgit v1.2.3-58-ga151