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authorBrian Gerst <brgerst@gmail.com>2015-04-04 14:58:23 +0200
committerIngo Molnar <mingo@kernel.org>2015-04-06 09:06:39 +0200
commit6a3713f001b3b53587e411ab0d3036ae9b0fb93b (patch)
treeb45db33d637a9465388642e04de58daa8892cf82
parentx86/alternatives: Fix ALTERNATIVE_2 padding generation properly (diff)
downloadlinux-6a3713f001b3b53587e411ab0d3036ae9b0fb93b.tar.xz
linux-6a3713f001b3b53587e411ab0d3036ae9b0fb93b.zip
x86/signal: Remove pax argument from restore_sigcontext
The 'pax' argument is unnecesary. Instead, store the RAX value directly in regs. This pattern goes all the way back to 2.1.106pre1, when restore_sigcontext() was changed to return an error code instead of EAX directly: https://git.kernel.org/cgit/linux/kernel/git/history/history.git/diff/arch/i386/kernel/signal.c?id=9a8f8b7ca3f319bd668298d447bdf32730e51174 In 2007 sigaltstack syscall support was added, where the return value of restore_sigcontext() was changed to carry the memory-copying failure code. But instead of putting 'ax' into regs->ax directly, it was carried in via a pointer and then returned, where the generic syscall return code copied it to regs->ax. So there was never any deeper reason for this suboptimal pattern, it was simply never noticed after being introduced. Signed-off-by: Brian Gerst <brgerst@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1428152303-17154-1-git-send-email-brgerst@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/ia32/ia32_signal.c17
-rw-r--r--arch/x86/include/asm/sighandling.h4
-rw-r--r--arch/x86/kernel/signal.c22
3 files changed, 15 insertions, 28 deletions
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 1f5e2b0e09ff..c81d35e6c7f1 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -161,8 +161,7 @@ int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
}
static int ia32_restore_sigcontext(struct pt_regs *regs,
- struct sigcontext_ia32 __user *sc,
- unsigned int *pax)
+ struct sigcontext_ia32 __user *sc)
{
unsigned int tmpflags, err = 0;
void __user *buf;
@@ -184,7 +183,7 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
RELOAD_SEG(es);
COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
- COPY(dx); COPY(cx); COPY(ip);
+ COPY(dx); COPY(cx); COPY(ip); COPY(ax);
/* Don't touch extended registers */
COPY_SEG_CPL3(cs);
@@ -197,8 +196,6 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
get_user_ex(tmp, &sc->fpstate);
buf = compat_ptr(tmp);
-
- get_user_ex(*pax, &sc->ax);
} get_user_catch(err);
err |= restore_xstate_sig(buf, 1);
@@ -213,7 +210,6 @@ asmlinkage long sys32_sigreturn(void)
struct pt_regs *regs = current_pt_regs();
struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
sigset_t set;
- unsigned int ax;
if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
@@ -226,9 +222,9 @@ asmlinkage long sys32_sigreturn(void)
set_current_blocked(&set);
- if (ia32_restore_sigcontext(regs, &frame->sc, &ax))
+ if (ia32_restore_sigcontext(regs, &frame->sc))
goto badframe;
- return ax;
+ return regs->ax;
badframe:
signal_fault(regs, frame, "32bit sigreturn");
@@ -240,7 +236,6 @@ asmlinkage long sys32_rt_sigreturn(void)
struct pt_regs *regs = current_pt_regs();
struct rt_sigframe_ia32 __user *frame;
sigset_t set;
- unsigned int ax;
frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
@@ -251,13 +246,13 @@ asmlinkage long sys32_rt_sigreturn(void)
set_current_blocked(&set);
- if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
+ if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;
if (compat_restore_altstack(&frame->uc.uc_stack))
goto badframe;
- return ax;
+ return regs->ax;
badframe:
signal_fault(regs, frame, "32bit rt sigreturn");
diff --git a/arch/x86/include/asm/sighandling.h b/arch/x86/include/asm/sighandling.h
index 7a958164088c..89db46752a8f 100644
--- a/arch/x86/include/asm/sighandling.h
+++ b/arch/x86/include/asm/sighandling.h
@@ -13,9 +13,7 @@
X86_EFLAGS_CF | X86_EFLAGS_RF)
void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
-
-int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
- unsigned long *pax);
+int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc);
int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
struct pt_regs *regs, unsigned long mask);
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index eaa2c5e3f2cd..53cc4085c3d7 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -61,8 +61,7 @@
regs->seg = GET_SEG(seg) | 3; \
} while (0)
-int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
- unsigned long *pax)
+int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
void __user *buf;
unsigned int tmpflags;
@@ -81,7 +80,7 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
#endif /* CONFIG_X86_32 */
COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
- COPY(dx); COPY(cx); COPY(ip);
+ COPY(dx); COPY(cx); COPY(ip); COPY(ax);
#ifdef CONFIG_X86_64
COPY(r8);
@@ -102,8 +101,6 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
regs->orig_ax = -1; /* disable syscall checks */
get_user_ex(buf, &sc->fpstate);
-
- get_user_ex(*pax, &sc->ax);
} get_user_catch(err);
err |= restore_xstate_sig(buf, config_enabled(CONFIG_X86_32));
@@ -545,7 +542,6 @@ asmlinkage unsigned long sys_sigreturn(void)
{
struct pt_regs *regs = current_pt_regs();
struct sigframe __user *frame;
- unsigned long ax;
sigset_t set;
frame = (struct sigframe __user *)(regs->sp - 8);
@@ -559,9 +555,9 @@ asmlinkage unsigned long sys_sigreturn(void)
set_current_blocked(&set);
- if (restore_sigcontext(regs, &frame->sc, &ax))
+ if (restore_sigcontext(regs, &frame->sc))
goto badframe;
- return ax;
+ return regs->ax;
badframe:
signal_fault(regs, frame, "sigreturn");
@@ -574,7 +570,6 @@ asmlinkage long sys_rt_sigreturn(void)
{
struct pt_regs *regs = current_pt_regs();
struct rt_sigframe __user *frame;
- unsigned long ax;
sigset_t set;
frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
@@ -585,13 +580,13 @@ asmlinkage long sys_rt_sigreturn(void)
set_current_blocked(&set);
- if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
+ if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;
if (restore_altstack(&frame->uc.uc_stack))
goto badframe;
- return ax;
+ return regs->ax;
badframe:
signal_fault(regs, frame, "rt_sigreturn");
@@ -786,7 +781,6 @@ asmlinkage long sys32_x32_rt_sigreturn(void)
struct pt_regs *regs = current_pt_regs();
struct rt_sigframe_x32 __user *frame;
sigset_t set;
- unsigned long ax;
frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
@@ -797,13 +791,13 @@ asmlinkage long sys32_x32_rt_sigreturn(void)
set_current_blocked(&set);
- if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
+ if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;
if (compat_restore_altstack(&frame->uc.uc_stack))
goto badframe;
- return ax;
+ return regs->ax;
badframe:
signal_fault(regs, frame, "x32 rt_sigreturn");