From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org
Cc: Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org, Brian Gerst <brgerst@gmail.com>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH 1/2] selftests/x86/sigreturn: Use CX, not AX, as the scratch register
Date: Mon, 12 Sep 2016 15:05:50 -0700 [thread overview]
Message-ID: <9ceeb24ea56925586c330dc46306f757ddea9fb5.1473717910.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1473717910.git.luto@kernel.org>
In-Reply-To: <cover.1473717910.git.luto@kernel.org>
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>
---
tools/testing/selftests/x86/sigreturn.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c
index 8a577e7070c6..246145b84a12 100644
--- a/tools/testing/selftests/x86/sigreturn.c
+++ b/tools/testing/selftests/x86/sigreturn.c
@@ -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++;
--
2.7.4
next prev parent reply other threads:[~2016-09-12 22:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-12 22:05 [PATCH 0/2] x86/64: espfix64 cleanups and testing Andy Lutomirski
2016-09-12 22:05 ` Andy Lutomirski [this message]
2016-09-13 22:08 ` [tip:x86/asm] selftests/x86/sigreturn: Use CX, not AX, as the scratch register tip-bot for Andy Lutomirski
2016-09-12 22:05 ` [PATCH 2/2] x86/entry/64: Clean up and document espfix64 stack setup Andy Lutomirski
2016-09-13 22:08 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-09-13 9:04 ` [PATCH 0/2] x86/64: espfix64 cleanups and testing Borislav Petkov
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