From cc7571b226c93b032164ebb3ff3b365651c4652f Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Sat, 8 Mar 2008 11:43:52 +0100 Subject: [PATCH] x86: Clear DF before calling signal handler 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. This become 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. This is a backport of patch e40cd10ccff3d9fbffd57b93780bee4b7b9bff51 ("x86: clear DF before calling signal handler") that has been applied in 2.6.25-rc. Signed-off-by: Aurelien Jarno Signed-off-by: Chris Wright Signed-off-by: Greg Kroah-Hartman --- 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 6ea19c25f90d..4eaaf78a5202 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -494,7 +494,7 @@ int ia32_setup_frame(int sig, struct k_sigaction *ka, regs->ss = __USER32_DS; set_fs(USER_DS); - regs->eflags &= ~TF_MASK; + regs->eflags &= ~(TF_MASK | 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->eflags &= ~TF_MASK; + regs->eflags &= ~(TF_MASK | 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 9bdd83022f5f..20056db6e80f 100644 --- a/arch/x86/kernel/signal_32.c +++ b/arch/x86/kernel/signal_32.c @@ -396,7 +396,7 @@ static int setup_frame(int sig, struct k_sigaction *ka, * The tracer may want to single-step inside the * handler too. */ - regs->eflags &= ~TF_MASK; + regs->eflags &= ~(TF_MASK | X86_EFLAGS_DF); if (test_thread_flag(TIF_SINGLESTEP)) ptrace_notify(SIGTRAP); @@ -489,7 +489,7 @@ 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->eflags &= ~TF_MASK; + regs->eflags &= ~(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 ab086b0357fc..62964c5a8e70 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->eflags &= ~TF_MASK; + regs->eflags &= ~(TF_MASK | X86_EFLAGS_DF); if (test_thread_flag(TIF_SINGLESTEP)) ptrace_notify(SIGTRAP); #ifdef DEBUG_SIG -- 2.39.5