init_fpu calls finit to initialize a task's xstate, while finit always
works on the current task. If we use PTRACE_GETFPREGS on another
process and both processes did not already use floating point, we get
a null pointer exception in finit.
This patch creates a new function finit_task that takes a task_struct
parameter. finit becomes a wrapper that simply calls finit_task with
current. On the plus side this avoids many calls to get_current which
would each resolve to an inline assembler mov instruction.
Signed-off-by: Daniel Glöckner <[email protected]>
---
arch/x86/include/asm/i387.h | 1 +
arch/x86/kernel/i387.c | 2 +-
arch/x86/math-emu/fpu_aux.c | 31 ++++++++++++++++++++-----------
3 files changed, 22 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 48f0004..10f349b 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -172,6 +172,7 @@ static inline void __save_init_fpu(struct task_struct *tsk)
#else /* CONFIG_X86_32 */
+extern void finit_task(struct task_struct *tsk);
extern void finit(void);
static inline void tolerant_fwait(void)
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index b0f61f0..f2f8540 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -136,7 +136,7 @@ int init_fpu(struct task_struct *tsk)
#ifdef CONFIG_X86_32
if (!HAVE_HWFP) {
memset(tsk->thread.xstate, 0, xstate_size);
- finit();
+ finit_task(tsk);
set_stopped_child_used_math(tsk);
return 0;
}
diff --git a/arch/x86/math-emu/fpu_aux.c b/arch/x86/math-emu/fpu_aux.c
index 491e737..aa09870 100644
--- a/arch/x86/math-emu/fpu_aux.c
+++ b/arch/x86/math-emu/fpu_aux.c
@@ -30,20 +30,29 @@ static void fclex(void)
}
/* Needs to be externally visible */
-void finit(void)
+void finit_task(struct task_struct *tsk)
{
- control_word = 0x037f;
- partial_status = 0;
- top = 0; /* We don't keep top in the status word internally. */
- fpu_tag_word = 0xffff;
+ struct i387_soft_struct *soft = &tsk->thread.xstate->soft;
+ struct address *oaddr, *iaddr;
+ soft->cwd = 0x037f;
+ soft->swd = 0;
+ soft->ftop = 0; /* We don't keep top in the status word internally. */
+ soft->twd = 0xffff;
/* The behaviour is different from that detailed in
Section 15.1.6 of the Intel manual */
- operand_address.offset = 0;
- operand_address.selector = 0;
- instruction_address.offset = 0;
- instruction_address.selector = 0;
- instruction_address.opcode = 0;
- no_ip_update = 1;
+ oaddr = (struct address *)&soft->foo;
+ oaddr->offset = 0;
+ oaddr->selector = 0;
+ iaddr = (struct address *)&soft->fip;
+ iaddr->offset = 0;
+ iaddr->selector = 0;
+ iaddr->opcode = 0;
+ soft->no_update = 1;
+}
+
+void finit(void)
+{
+ finit_task(current);
}
/*
--
1.5.6
--
Dipl.-Math. Daniel Glöckner, emlix GmbH, http://www.emlix.com
Fon +49 551 30664-0, Fax -11, Bahnhofsallee 1b, 37081 Göttingen, Germany
Geschäftsführung: Dr. Uwe Kracke, Dr. Cord Seele, Ust-IdNr.: DE 205 198 055
Sitz der Gesellschaft: Göttingen, Amtsgericht Göttingen HR B 3160
emlix - your embedded linux partner
* Daniel Gl?ckner <[email protected]> wrote:
> init_fpu calls finit to initialize a task's xstate, while finit always
> works on the current task. If we use PTRACE_GETFPREGS on another
> process and both processes did not already use floating point, we get
> a null pointer exception in finit.
>
> This patch creates a new function finit_task that takes a task_struct
> parameter. finit becomes a wrapper that simply calls finit_task with
> current. On the plus side this avoids many calls to get_current which
> would each resolve to an inline assembler mov instruction.
>
> Signed-off-by: Daniel Gl?ckner <[email protected]>
> ---
> arch/x86/include/asm/i387.h | 1 +
> arch/x86/kernel/i387.c | 2 +-
> arch/x86/math-emu/fpu_aux.c | 31 ++++++++++++++++++++-----------
> 3 files changed, 22 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
> index 48f0004..10f349b 100644
> --- a/arch/x86/include/asm/i387.h
> +++ b/arch/x86/include/asm/i387.h
> @@ -172,6 +172,7 @@ static inline void __save_init_fpu(struct task_struct *tsk)
>
> #else /* CONFIG_X86_32 */
>
> +extern void finit_task(struct task_struct *tsk);
> extern void finit(void);
>
> static inline void tolerant_fwait(void)
> diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
> index b0f61f0..f2f8540 100644
> --- a/arch/x86/kernel/i387.c
> +++ b/arch/x86/kernel/i387.c
> @@ -136,7 +136,7 @@ int init_fpu(struct task_struct *tsk)
> #ifdef CONFIG_X86_32
> if (!HAVE_HWFP) {
> memset(tsk->thread.xstate, 0, xstate_size);
> - finit();
> + finit_task(tsk);
> set_stopped_child_used_math(tsk);
> return 0;
> }
> diff --git a/arch/x86/math-emu/fpu_aux.c b/arch/x86/math-emu/fpu_aux.c
> index 491e737..aa09870 100644
> --- a/arch/x86/math-emu/fpu_aux.c
> +++ b/arch/x86/math-emu/fpu_aux.c
> @@ -30,20 +30,29 @@ static void fclex(void)
> }
>
> /* Needs to be externally visible */
> -void finit(void)
> +void finit_task(struct task_struct *tsk)
ok, the fix looks good - but we sure want to define this
function in the "# CONFIG_MATH_EMU is not set" case too, agreed?
Ingo
On 03/02/2009 08:52 PM, Ingo Molnar wrote:
> * Daniel Gl?ckner <[email protected]> wrote:
[..]
>> This patch creates a new function finit_task that takes a task_struct
>> parameter. finit becomes a wrapper that simply calls finit_task with
>> current. On the plus side this avoids many calls to get_current which
>> would each resolve to an inline assembler mov instruction.
[..]
>> --- a/arch/x86/kernel/i387.c
>> +++ b/arch/x86/kernel/i387.c
>> @@ -136,7 +136,7 @@ int init_fpu(struct task_struct *tsk)
>> #ifdef CONFIG_X86_32
>> if (!HAVE_HWFP) {
>> memset(tsk->thread.xstate, 0, xstate_size);
>> - finit();
>> + finit_task(tsk);
>> set_stopped_child_used_math(tsk);
>> return 0;
>> }
[..]
>
> ok, the fix looks good - but we sure want to define this
> function in the "# CONFIG_MATH_EMU is not set" case too, agreed?
To avoid linker errors if the compiler emits the call although !HAVE_HWFP
is always false? Sounds plausible. I also removed finit from i387.h as the
only other external call site, reg_ld_str.c, gets its prototype from
fpu_proto.h.
Signed-off-by: Daniel Gl?ckner <[email protected]>
---
arch/x86/include/asm/i387.h | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 10f349b..71c9e51 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -172,8 +172,13 @@ static inline void __save_init_fpu(struct task_struct *tsk)
#else /* CONFIG_X86_32 */
+#ifdef CONFIG_MATH_EMULATION
extern void finit_task(struct task_struct *tsk);
-extern void finit(void);
+#else
+static inline void finit_task(struct task_struct *tsk)
+{
+}
+#endif
static inline void tolerant_fwait(void)
{
--
1.5.6
--
Dipl.-Math. Daniel Gl?ckner, emlix GmbH, http://www.emlix.com
Fon +49 551 30664-0, Fax -11, Bahnhofsallee 1b, 37081 G?ttingen, Germany
Gesch?ftsf?hrung: Dr. Uwe Kracke, Dr. Cord Seele, Ust-IdNr.: DE 205 198 055
Sitz der Gesellschaft: G?ttingen, Amtsgericht G?ttingen HR B 3160
emlix - your embedded linux partner
* Daniel Gl?ckner <[email protected]> wrote:
> On 03/02/2009 08:52 PM, Ingo Molnar wrote:
> > * Daniel Gl?ckner <[email protected]> wrote:
> [..]
> >> This patch creates a new function finit_task that takes a task_struct
> >> parameter. finit becomes a wrapper that simply calls finit_task with
> >> current. On the plus side this avoids many calls to get_current which
> >> would each resolve to an inline assembler mov instruction.
> [..]
> >> --- a/arch/x86/kernel/i387.c
> >> +++ b/arch/x86/kernel/i387.c
> >> @@ -136,7 +136,7 @@ int init_fpu(struct task_struct *tsk)
> >> #ifdef CONFIG_X86_32
> >> if (!HAVE_HWFP) {
> >> memset(tsk->thread.xstate, 0, xstate_size);
> >> - finit();
> >> + finit_task(tsk);
> >> set_stopped_child_used_math(tsk);
> >> return 0;
> >> }
> [..]
> >
> > ok, the fix looks good - but we sure want to define this
> > function in the "# CONFIG_MATH_EMU is not set" case too, agreed?
>
> To avoid linker errors if the compiler emits the call although
> !HAVE_HWFP is always false? Sounds plausible. I also removed
> finit from i387.h as the only other external call site,
> reg_ld_str.c, gets its prototype from fpu_proto.h.
Could you please send a single combo patch with a full
changelog, etc.
Thanks,
Ingo
init_fpu calls finit to initialize a task's xstate, while finit always
works on the current task. If we use PTRACE_GETFPREGS on another
process and both processes did not already use floating point, we get
a null pointer exception in finit.
This patch creates a new function finit_task that takes a task_struct
parameter. finit becomes a wrapper that simply calls finit_task with
current. On the plus side this avoids many calls to get_current which
would each resolve to an inline assembler mov instruction.
An empty finit_task has been added to i387.h to avoid linker errors in
case the compiler still emits the call in init_fpu when
CONFIG_MATH_EMULATION is not defined.
The declaration of finit in i387.h has been removed as the remaining
code using this function gets its prototype from fpu_proto.h.
Signed-off-by: Daniel Gl?ckner <[email protected]>
---
arch/x86/include/asm/i387.h | 8 +++++++-
arch/x86/kernel/i387.c | 2 +-
arch/x86/math-emu/fpu_aux.c | 31 ++++++++++++++++++++-----------
3 files changed, 28 insertions(+), 13 deletions(-)
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 48f0004..71c9e51 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -172,7 +172,13 @@ static inline void __save_init_fpu(struct task_struct *tsk)
#else /* CONFIG_X86_32 */
-extern void finit(void);
+#ifdef CONFIG_MATH_EMULATION
+extern void finit_task(struct task_struct *tsk);
+#else
+static inline void finit_task(struct task_struct *tsk)
+{
+}
+#endif
static inline void tolerant_fwait(void)
{
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index b0f61f0..f2f8540 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -136,7 +136,7 @@ int init_fpu(struct task_struct *tsk)
#ifdef CONFIG_X86_32
if (!HAVE_HWFP) {
memset(tsk->thread.xstate, 0, xstate_size);
- finit();
+ finit_task(tsk);
set_stopped_child_used_math(tsk);
return 0;
}
diff --git a/arch/x86/math-emu/fpu_aux.c b/arch/x86/math-emu/fpu_aux.c
index 491e737..aa09870 100644
--- a/arch/x86/math-emu/fpu_aux.c
+++ b/arch/x86/math-emu/fpu_aux.c
@@ -30,20 +30,29 @@ static void fclex(void)
}
/* Needs to be externally visible */
-void finit(void)
+void finit_task(struct task_struct *tsk)
{
- control_word = 0x037f;
- partial_status = 0;
- top = 0; /* We don't keep top in the status word internally. */
- fpu_tag_word = 0xffff;
+ struct i387_soft_struct *soft = &tsk->thread.xstate->soft;
+ struct address *oaddr, *iaddr;
+ soft->cwd = 0x037f;
+ soft->swd = 0;
+ soft->ftop = 0; /* We don't keep top in the status word internally. */
+ soft->twd = 0xffff;
/* The behaviour is different from that detailed in
Section 15.1.6 of the Intel manual */
- operand_address.offset = 0;
- operand_address.selector = 0;
- instruction_address.offset = 0;
- instruction_address.selector = 0;
- instruction_address.opcode = 0;
- no_ip_update = 1;
+ oaddr = (struct address *)&soft->foo;
+ oaddr->offset = 0;
+ oaddr->selector = 0;
+ iaddr = (struct address *)&soft->fip;
+ iaddr->offset = 0;
+ iaddr->selector = 0;
+ iaddr->opcode = 0;
+ soft->no_update = 1;
+}
+
+void finit(void)
+{
+ finit_task(current);
}
/*
--
1.5.6
--
Dipl.-Math. Daniel Gl?ckner, emlix GmbH, http://www.emlix.com
Fon +49 551 30664-0, Fax -11, Bahnhofsallee 1b, 37081 G?ttingen, Germany
Gesch?ftsf?hrung: Dr. Uwe Kracke, Dr. Cord Seele, Ust-IdNr.: DE 205 198 055
Sitz der Gesellschaft: G?ttingen, Amtsgericht G?ttingen HR B 3160
emlix - your embedded linux partner