From 7fe977dab356fbd7e86aa10bf83891761107c57c Mon Sep 17 00:00:00 2001
From: Jan Beulich <JBeulich@novell.com>
Date: Thu, 2 Sep 2010 14:01:58 +0100
Subject: i386: Make kernel_execve() suitable for stack unwinding
The explicit saving and restoring of %ebx was confusing stack
unwind data consumers, and it is plain unnecessary to do this
within the asm(), since that was only introduced for PIC user
mode consumers of the original _syscall3() macro this was
derived from.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Arnd Bergmann <arnd@arndb.de>
LKML-Reference: <4C7FBC660200007800013F95@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/sys_i386_32.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'arch')
diff --git a/arch/x86/kernel/sys_i386_32.c b/arch/x86/kernel/sys_i386_32.c
index d5e0662..0b0cb5f 100644
--- a/arch/x86/kernel/sys_i386_32.c
+++ b/arch/x86/kernel/sys_i386_32.c
@@ -33,8 +33,8 @@ int kernel_execve(const char *filename,
const char *const envp[])
{
long __res;
- asm volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx"
+ asm volatile ("int $0x80"
: "=a" (__res)
- : "0" (__NR_execve), "ri" (filename), "c" (argv), "d" (envp) : "memory");
+ : "0" (__NR_execve), "b" (filename), "c" (argv), "d" (envp) : "memory");
return __res;
}
--
cgit v1.1
From d7acb92fea932ad2e7846480aeacddc2c03c8485 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@linux.intel.com>
Date: Wed, 13 Oct 2010 16:00:29 -0700
Subject: x86-64, asm: If the assembler supports fxsave64, use it
Kbuild allows for us to probe for the existence of specific constructs
in the assembler, use them to find out if we can use fxsave64 and
permit the compiler to generate better code.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
arch/x86/Makefile | 8 ++++++--
arch/x86/include/asm/i387.h | 2 +-
2 files changed, 7 insertions(+), 3 deletions(-)
(limited to 'arch')
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 8aa1b59..40668a9 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -96,8 +96,12 @@ cfi := $(call as-instr,.cfi_startproc\n.cfi_rel_offset $(sp-y)$(comma)0\n.cfi_en
# is .cfi_signal_frame supported too?
cfi-sigframe := $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1)
cfi-sections := $(call as-instr,.cfi_sections .debug_frame,-DCONFIG_AS_CFI_SECTIONS=1)
-KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections)
-KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections)
+
+# does binutils support specific instructions?
+asinstr := $(call as-instr,fxsaveq (%rax),-DCONFIG_AS_FXSAVEQ=1)
+
+KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr)
+KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr)
LDFLAGS := -m elf_$(UTS_MACHINE)
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index a73a8d5..70f105b 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -175,7 +175,7 @@ static inline void fpu_fxsave(struct fpu *fpu)
uses any extended registers for addressing, a second REX prefix
will be generated (to the assembler, rex64 followed by semicolon
is a separate instruction), and hence the 64-bitness is lost. */
-#if 0
+#ifdef CONFIG_AS_FXSAVEQ
/* Using "fxsaveq %0" would be the ideal choice, but is only supported
starting with gas 2.16. */
__asm__ __volatile__("fxsaveq %0"
--
cgit v1.1