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Date: Fri, 23 May 2008 16:26:37 -0700
From: Suresh Siddha <suresh.b.siddha@...el.com>
To: hpa@...or.com, tglx@...utronix.de, mingo@...e.hu
Cc: linux-kernel@...r.kernel.org
Subject: [patch] x86: fix broken math-emu with lazy allocation of fpu area
Fix the math emulation that got broken with the recent lazy allocation of FPU
area. init_fpu() need to be added for the math-emulation path aswell
for the FPU area allocation.
math emulation enabled kernel booted fine with this, in the presence
of "no387 nofxsr" boot param.
Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
---
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index e03cc95..eb9ddd8 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -56,6 +56,11 @@ void __cpuinit mxcsr_feature_mask_init(void)
void __init init_thread_xstate(void)
{
+ if (!HAVE_HWFP) {
+ xstate_size = sizeof(struct i387_soft_struct);
+ return;
+ }
+
if (cpu_has_fxsr)
xstate_size = sizeof(struct i387_fxsave_struct);
#ifdef CONFIG_X86_32
@@ -94,7 +99,7 @@ void __cpuinit fpu_init(void)
int init_fpu(struct task_struct *tsk)
{
if (tsk_used_math(tsk)) {
- if (tsk == current)
+ if (HAVE_HWFP && tsk == current)
unlazy_fpu(tsk);
return 0;
}
@@ -109,6 +114,15 @@ int init_fpu(struct task_struct *tsk)
return -ENOMEM;
}
+#ifdef CONFIG_X86_32
+ if (!HAVE_HWFP) {
+ memset(tsk->thread.xstate, 0, xstate_size);
+ finit();
+ set_stopped_child_used_math(tsk);
+ return 0;
+ }
+#endif
+
if (cpu_has_fxsr) {
struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
@@ -330,13 +344,13 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
struct user_i387_ia32_struct env;
int ret;
- if (!HAVE_HWFP)
- return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
-
ret = init_fpu(target);
if (ret)
return ret;
+ if (!HAVE_HWFP)
+ return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
+
if (!cpu_has_fxsr) {
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.xstate->fsave, 0,
@@ -360,15 +374,15 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
struct user_i387_ia32_struct env;
int ret;
- if (!HAVE_HWFP)
- return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
-
ret = init_fpu(target);
if (ret)
return ret;
set_stopped_child_used_math(target);
+ if (!HAVE_HWFP)
+ return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
+
if (!cpu_has_fxsr) {
return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&target->thread.xstate->fsave, 0, -1);
@@ -474,18 +488,18 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
int restore_i387_ia32(struct _fpstate_ia32 __user *buf)
{
int err;
+ struct task_struct *tsk = current;
- if (HAVE_HWFP) {
- struct task_struct *tsk = current;
-
+ if (HAVE_HWFP)
clear_fpu(tsk);
- if (!used_math()) {
- err = init_fpu(tsk);
- if (err)
- return err;
- }
+ if (!used_math()) {
+ err = init_fpu(tsk);
+ if (err)
+ return err;
+ }
+ if (HAVE_HWFP) {
if (cpu_has_fxsr)
err = restore_i387_fxsave(buf);
else
diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c
index 6e38d87..c7b06fe 100644
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -30,6 +30,7 @@
#include <asm/uaccess.h>
#include <asm/desc.h>
#include <asm/user.h>
+#include <asm/i387.h>
#include "fpu_system.h"
#include "fpu_emu.h"
@@ -146,6 +147,13 @@ asmlinkage void math_emulate(long arg)
unsigned long code_limit = 0; /* Initialized to stop compiler warnings */
struct desc_struct code_descriptor;
+ if (!used_math()) {
+ if (init_fpu(current)) {
+ do_group_exit(SIGKILL);
+ return;
+ }
+ }
+
#ifdef RE_ENTRANT_CHECKING
if (emulating) {
printk("ERROR: wm-FPU-emu is not RE-ENTRANT!\n");
@@ -153,11 +161,6 @@ asmlinkage void math_emulate(long arg)
RE_ENTRANT_CHECK_ON;
#endif /* RE_ENTRANT_CHECKING */
- if (!used_math()) {
- finit();
- set_used_math();
- }
-
SETUP_DATA_AREA(arg);
FPU_ORIG_EIP = FPU_EIP;
diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h
index 6b722d3..37672f7 100644
--- a/include/asm-x86/i387.h
+++ b/include/asm-x86/i387.h
@@ -193,6 +193,8 @@ static inline int restore_i387(struct _fpstate __user *buf)
#else /* CONFIG_X86_32 */
+extern void finit(void);
+
static inline void tolerant_fwait(void)
{
asm volatile("fnclex ; fwait");
--
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