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authorAurelien Jarno <aurelien@aurel32.net>2008-03-05 19:14:24 +0100
committerIngo Molnar <mingo@elte.hu>2008-03-07 16:39:14 +0100
commite40cd10ccff3d9fbffd57b93780bee4b7b9bff51 (patch)
treebdc58b9f84e7e4bd37da3bfb1f9a445a1560c0c3
parentce4796d1e16cf3761dc2a02b8d588667d05b3078 (diff)
downloadlinux-e40cd10ccff3d9fbffd57b93780bee4b7b9bff51.tar.bz2
x86: clear DF before calling signal handler
The Linux kernel currently does not clear the direction flag before calling a signal handler, whereas the x86/x86-64 ABI requires that. Linux had this behavior/bug forever, but this becomes a real problem with gcc version 4.3, which assumes that the direction flag is correctly cleared at the entry of a function. This patches changes the setup_frame() functions to clear the direction before entering the signal handler. Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r--arch/x86/ia32/ia32_signal.c4
-rw-r--r--arch/x86/kernel/signal_32.c4
-rw-r--r--arch/x86/kernel/signal_64.c2
3 files changed, 5 insertions, 5 deletions
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 1c0503bdfb1a..5e7771a3ba2f 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -500,7 +500,7 @@ int ia32_setup_frame(int sig, struct k_sigaction *ka,
regs->ss = __USER32_DS;
set_fs(USER_DS);
- regs->flags &= ~X86_EFLAGS_TF;
+ regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF);
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
@@ -600,7 +600,7 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
regs->ss = __USER32_DS;
set_fs(USER_DS);
- regs->flags &= ~X86_EFLAGS_TF;
+ regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF);
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
index caee1f002fed..0157a6f0f41f 100644
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -407,7 +407,7 @@ static int setup_frame(int sig, struct k_sigaction *ka,
* The tracer may want to single-step inside the
* handler too.
*/
- regs->flags &= ~TF_MASK;
+ regs->flags &= ~(TF_MASK | X86_EFLAGS_DF);
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
@@ -500,7 +500,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
* The tracer may want to single-step inside the
* handler too.
*/
- regs->flags &= ~TF_MASK;
+ regs->flags &= ~(TF_MASK | X86_EFLAGS_DF);
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
index 7347bb14e306..56b72fb67f9b 100644
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -295,7 +295,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
see include/asm-x86_64/uaccess.h for details. */
set_fs(USER_DS);
- regs->flags &= ~X86_EFLAGS_TF;
+ regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF);
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
#ifdef DEBUG_SIG