Commit cced0b24 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Thomas Gleixner
Browse files

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: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/982ce58ae8dea2f1e57093ee894760e35267e751.1593191971.git.luto@kernel.org
parent a61fa279

tools/testing/selftests/x86/Makefile

+2 −2
Original line number Original line Diff line number Diff line
@@ -70,10 +70,10 @@ all_64: $(BINARIES_64) 




EXTRA_CLEAN := $(BINARIES_32) $(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

	$(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

	$(CC) -m64 -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl





# x86_64 users should be encouraged to install 32-bit libraries

# x86_64 users should be encouraged to install 32-bit libraries

tools/testing/selftests/x86/helpers.h

0 → 100644
+41 −0
Original line number Original line Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

#ifndef __SELFTESTS_X86_HELPERS_H

#define __SELFTESTS_X86_HELPERS_H



#include <asm/processor-flags.h>



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 */

tools/testing/selftests/x86/single_step_syscall.c

+2 −15
Original line number Original line Diff line number Diff line
@@ -31,6 +31,8 @@ 
#include <sys/ptrace.h>

#include <sys/ptrace.h>

#include <sys/user.h>

#include <sys/user.h>





#include "helpers.h"



static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),

static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),

		       int flags)

		       int flags)

{

{
@@ -67,21 +69,6 @@ static unsigned char altstack_data[SIGSTKSZ]; 
# define INT80_CLOBBERS

# define INT80_CLOBBERS

#endif

#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)

static void sigtrap(int sig, siginfo_t *info, void *ctx_void)

{

{

	ucontext_t *ctx = (ucontext_t*)ctx_void;

	ucontext_t *ctx = (ucontext_t*)ctx_void;

tools/testing/selftests/x86/syscall_arg_fault.c

+1 −20
Original line number Original line Diff line number Diff line
@@ -15,30 +15,11 @@ 
#include <setjmp.h>

#include <setjmp.h>

#include <errno.h>

#include <errno.h>





#ifdef __x86_64__

#include "helpers.h"

# define WIDTH "q"

#else

# define WIDTH "l"

#endif





/* Our sigaltstack scratch space. */

/* Our sigaltstack scratch space. */

static unsigned char altstack_data[SIGSTKSZ];

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 *),

static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),

		       int flags)

		       int flags)

{

{

tools/testing/selftests/x86/syscall_nt.c

+1 −19
Original line number Original line Diff line number Diff line
@@ -13,29 +13,11 @@ 
#include <signal.h>

#include <signal.h>

#include <err.h>

#include <err.h>

#include <sys/syscall.h>

#include <sys/syscall.h>

#include <asm/processor-flags.h>





#ifdef __x86_64__

#include "helpers.h"

# define WIDTH "q"

#else

# define WIDTH "l"

#endif





static unsigned int nerrs;

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 *),

static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),

		       int flags)

		       int flags)

{

{

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