From 6a3713f001b3b53587e411ab0d3036ae9b0fb93b Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Sat, 4 Apr 2015 08:58:23 -0400 Subject: [PATCH] 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 Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1428152303-17154-1-git-send-email-brgerst@gmail.com Signed-off-by: Ingo Molnar --- arch/x86/ia32/ia32_signal.c | 17 ++++++----------- arch/x86/include/asm/sighandling.h | 4 +--- arch/x86/kernel/signal.c | 22 ++++++++-------------- 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"); -- 2.20.1