From cced0b24bb545bfe74fea96de84adc23c0146b05 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Fri, 26 Jun 2020 10:21:16 -0700 Subject: [PATCH] selftests/x86: Consolidate and fix get/set_eflags() helpers There are several copies of get_eflags() and set_eflags() and they all are buggy. Consolidate them and fix them. The fixes are: Add memory clobbers. These are probably unnecessary but they make sure that the compiler doesn't move something past one of these calls when it shouldn't. Respect the redzone on x86_64. There has no failure been observed related to this, but it's definitely a bug. Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/982ce58ae8dea2f1e57093ee894760e35267e751.1593191971.git.luto@kernel.org --- tools/testing/selftests/x86/Makefile | 4 +- tools/testing/selftests/x86/helpers.h | 41 +++++++++++++++++++ .../selftests/x86/single_step_syscall.c | 17 +------- .../testing/selftests/x86/syscall_arg_fault.c | 21 +--------- tools/testing/selftests/x86/syscall_nt.c | 20 +-------- tools/testing/selftests/x86/test_vsyscall.c | 15 +------ tools/testing/selftests/x86/unwind_vdso.c | 23 +---------- 7 files changed, 51 insertions(+), 90 deletions(-) create mode 100644 tools/testing/selftests/x86/helpers.h diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile index 5f16821c7f63..d2796ea98c5a 100644 --- a/tools/testing/selftests/x86/Makefile +++ b/tools/testing/selftests/x86/Makefile @@ -70,10 +70,10 @@ all_64: $(BINARIES_64) EXTRA_CLEAN := $(BINARIES_32) $(BINARIES_64) -$(BINARIES_32): $(OUTPUT)/%_32: %.c +$(BINARIES_32): $(OUTPUT)/%_32: %.c helpers.h $(CC) -m32 -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl -lm -$(BINARIES_64): $(OUTPUT)/%_64: %.c +$(BINARIES_64): $(OUTPUT)/%_64: %.c helpers.h $(CC) -m64 -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl # x86_64 users should be encouraged to install 32-bit libraries diff --git a/tools/testing/selftests/x86/helpers.h b/tools/testing/selftests/x86/helpers.h new file mode 100644 index 000000000000..f5ff2a2615df --- /dev/null +++ b/tools/testing/selftests/x86/helpers.h @@ -0,0 +1,41 @@ +// SPDX-License-Identifier: GPL-2.0-only +#ifndef __SELFTESTS_X86_HELPERS_H +#define __SELFTESTS_X86_HELPERS_H + +#include + +static inline unsigned long get_eflags(void) +{ + unsigned long eflags; + + asm volatile ( +#ifdef __x86_64__ + "subq $128, %%rsp\n\t" + "pushfq\n\t" + "popq %0\n\t" + "addq $128, %%rsp" +#else + "pushfl\n\t" + "popl %0" +#endif + : "=r" (eflags) :: "memory"); + + return eflags; +} + +static inline void set_eflags(unsigned long eflags) +{ + asm volatile ( +#ifdef __x86_64__ + "subq $128, %%rsp\n\t" + "pushq %0\n\t" + "popfq\n\t" + "addq $128, %%rsp" +#else + "pushl %0\n\t" + "popfl" +#endif + :: "r" (eflags) : "flags", "memory"); +} + +#endif /* __SELFTESTS_X86_HELPERS_H */ diff --git a/tools/testing/selftests/x86/single_step_syscall.c b/tools/testing/selftests/x86/single_step_syscall.c index 1063328e275c..120ac741fe44 100644 --- a/tools/testing/selftests/x86/single_step_syscall.c +++ b/tools/testing/selftests/x86/single_step_syscall.c @@ -31,6 +31,8 @@ #include #include +#include "helpers.h" + static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags) { @@ -67,21 +69,6 @@ static unsigned char altstack_data[SIGSTKSZ]; # define INT80_CLOBBERS #endif -static unsigned long get_eflags(void) -{ - unsigned long eflags; - asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags)); - return eflags; -} - -static void set_eflags(unsigned long eflags) -{ - asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH - : : "rm" (eflags) : "flags"); -} - -#define X86_EFLAGS_TF (1UL << 8) - static void sigtrap(int sig, siginfo_t *info, void *ctx_void) { ucontext_t *ctx = (ucontext_t*)ctx_void; diff --git a/tools/testing/selftests/x86/syscall_arg_fault.c b/tools/testing/selftests/x86/syscall_arg_fault.c index bc0ecc2e862e..5b7abebbcbb9 100644 --- a/tools/testing/selftests/x86/syscall_arg_fault.c +++ b/tools/testing/selftests/x86/syscall_arg_fault.c @@ -15,30 +15,11 @@ #include #include -#ifdef __x86_64__ -# define WIDTH "q" -#else -# define WIDTH "l" -#endif +#include "helpers.h" /* Our sigaltstack scratch space. */ static unsigned char altstack_data[SIGSTKSZ]; -static unsigned long get_eflags(void) -{ - unsigned long eflags; - asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags)); - return eflags; -} - -static void set_eflags(unsigned long eflags) -{ - asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH - : : "rm" (eflags) : "flags"); -} - -#define X86_EFLAGS_TF (1UL << 8) - static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags) { diff --git a/tools/testing/selftests/x86/syscall_nt.c b/tools/testing/selftests/x86/syscall_nt.c index 5fc82b9cebed..970e5e14d96d 100644 --- a/tools/testing/selftests/x86/syscall_nt.c +++ b/tools/testing/selftests/x86/syscall_nt.c @@ -13,29 +13,11 @@ #include #include #include -#include -#ifdef __x86_64__ -# define WIDTH "q" -#else -# define WIDTH "l" -#endif +#include "helpers.h" static unsigned int nerrs; -static unsigned long get_eflags(void) -{ - unsigned long eflags; - asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags)); - return eflags; -} - -static void set_eflags(unsigned long eflags) -{ - asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH - : : "rm" (eflags) : "flags"); -} - static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags) { diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c index a4f4d4cf22c3..c41f24b517f4 100644 --- a/tools/testing/selftests/x86/test_vsyscall.c +++ b/tools/testing/selftests/x86/test_vsyscall.c @@ -20,6 +20,8 @@ #include #include +#include "helpers.h" + #ifdef __x86_64__ # define VSYS(x) (x) #else @@ -493,21 +495,8 @@ static int test_process_vm_readv(void) } #ifdef __x86_64__ -#define X86_EFLAGS_TF (1UL << 8) static volatile sig_atomic_t num_vsyscall_traps; -static unsigned long get_eflags(void) -{ - unsigned long eflags; - asm volatile ("pushfq\n\tpopq %0" : "=rm" (eflags)); - return eflags; -} - -static void set_eflags(unsigned long eflags) -{ - asm volatile ("pushq %0\n\tpopfq" : : "rm" (eflags) : "flags"); -} - static void sigtrap(int sig, siginfo_t *info, void *ctx_void) { ucontext_t *ctx = (ucontext_t *)ctx_void; diff --git a/tools/testing/selftests/x86/unwind_vdso.c b/tools/testing/selftests/x86/unwind_vdso.c index 0075ccd65407..4c311e1af4c7 100644 --- a/tools/testing/selftests/x86/unwind_vdso.c +++ b/tools/testing/selftests/x86/unwind_vdso.c @@ -11,6 +11,8 @@ #include #include +#include "helpers.h" + #if defined(__GLIBC__) && __GLIBC__ == 2 && __GLIBC_MINOR__ < 16 int main() @@ -53,27 +55,6 @@ static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), err(1, "sigaction"); } -#ifdef __x86_64__ -# define WIDTH "q" -#else -# define WIDTH "l" -#endif - -static unsigned long get_eflags(void) -{ - unsigned long eflags; - asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags)); - return eflags; -} - -static void set_eflags(unsigned long eflags) -{ - asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH - : : "rm" (eflags) : "flags"); -} - -#define X86_EFLAGS_TF (1UL << 8) - static volatile sig_atomic_t nerrs; static unsigned long sysinfo; static bool got_sysinfo = false;