[prev in list] [next in list] [prev in thread] [next in thread] 

List:       git-commits-head
Subject:    x86: clear DF before calling signal handler
From:       Linux Kernel Mailing List <linux-kernel () vger ! kernel ! org>
Date:       2008-03-07 19:59:14
Message-ID: 200803071959.m27JxEYu002120 () hera ! kernel ! org
[Download RAW message or body]

Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e40cd10ccff3d9fbffd57b93780bee4b7b9bff51
Commit:     e40cd10ccff3d9fbffd57b93780bee4b7b9bff51
Parent:     ce4796d1e16cf3761dc2a02b8d588667d05b3078
Author:     Aurelien Jarno <aurelien@aurel32.net>
AuthorDate: Wed Mar 5 19:14:24 2008 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Fri Mar 7 16:39:14 2008 +0100

    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>
---
 arch/x86/ia32/ia32_signal.c |    4 ++--
 arch/x86/kernel/signal_32.c |    4 ++--
 arch/x86/kernel/signal_64.c |    2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 1c0503b..5e7771a 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 caee1f0..0157a6f 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 7347bb1..56b72fb 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
--
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
[prev in list] [next in list] [prev in thread] [next in thread] 

Configure | About | News | Add a list | Sponsored by KoreLogic