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selftests/x86/sigreturn: Use CX, not AX, as the scratch register

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RAX is handled specially in ESPFIX64.  Use CX as our scratch
register so that, if something goes wrong with RAX handling, we'll
notice.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/9ceeb24ea56925586c330dc46306f757ddea9fb5.1473717910.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2016-09-12 15:05:50 -07:00 committed by Ingo Molnar
parent 5a8ff54c26
commit 1ef0199a1a
1 changed files with 8 additions and 8 deletions
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16
tools/testing/selftests/x86/sigreturn.c
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@ -106,7 +106,7 @@ asm (".pushsection .text\n\t"
".type int3, @function\n\t"
".align 4096\n\t"
"int3:\n\t"
"mov %ss,%eax\n\t"
"mov %ss,%ecx\n\t"
"int3\n\t"
".size int3, . - int3\n\t"
".align 4096, 0xcc\n\t"
@ -306,7 +306,7 @@ static volatile sig_atomic_t sig_corrupt_final_ss;
#ifdef __x86_64__
# define REG_IP REG_RIP
# define REG_SP REG_RSP
# define REG_AX REG_RAX
# define REG_CX REG_RCX
struct selectors {
unsigned short cs, gs, fs, ss;
@ -326,7 +326,7 @@ static unsigned short *csptr(ucontext_t *ctx)
#else
# define REG_IP REG_EIP
# define REG_SP REG_ESP
# define REG_AX REG_EAX
# define REG_CX REG_ECX
static greg_t *ssptr(ucontext_t *ctx)
{
@ -457,10 +457,10 @@ static void sigusr1(int sig, siginfo_t *info, void *ctx_void)
ctx->uc_mcontext.gregs[REG_IP] =
sig_cs == code16_sel ? 0 : (unsigned long)&int3;
ctx->uc_mcontext.gregs[REG_SP] = (unsigned long)0x8badf00d5aadc0deULL;
ctx->uc_mcontext.gregs[REG_AX] = 0;
ctx->uc_mcontext.gregs[REG_CX] = 0;
memcpy(&requested_regs, &ctx->uc_mcontext.gregs, sizeof(gregset_t));
requested_regs[REG_AX] = *ssptr(ctx); /* The asm code does this. */
requested_regs[REG_CX] = *ssptr(ctx); /* The asm code does this. */
return;
}
@ -482,7 +482,7 @@ static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
unsigned short ss;
asm ("mov %%ss,%0" : "=r" (ss));
greg_t asm_ss = ctx->uc_mcontext.gregs[REG_AX];
greg_t asm_ss = ctx->uc_mcontext.gregs[REG_CX];
if (asm_ss != sig_ss && sig == SIGTRAP) {
/* Sanity check failure. */
printf("[FAIL]\tSIGTRAP: ss = %hx, frame ss = %hx, ax = %llx\n",
@ -654,8 +654,8 @@ static int test_valid_sigreturn(int cs_bits, bool use_16bit_ss, int force_ss)
#endif
/* Sanity check on the kernel */
if (i == REG_AX && requested_regs[i] != resulting_regs[i]) {
printf("[FAIL]\tAX (saved SP) mismatch: requested 0x%llx; got 0x%llx\n",
if (i == REG_CX && requested_regs[i] != resulting_regs[i]) {
printf("[FAIL]\tCX (saved SP) mismatch: requested 0x%llx; got 0x%llx\n",
(unsigned long long)requested_regs[i],
(unsigned long long)resulting_regs[i]);
nerrs++;