* [PATCH v2 0/2] powerpc/math-emu: two patches for the emulation of the FPU unimplemented instructions
@ 2013-07-12 5:36 Kevin Hao
2013-07-12 5:36 ` [PATCH v2 1/2] powerpc/math-emu: move the flush FPU state function into do_mathemu Kevin Hao
2013-07-12 5:36 ` [PATCH v2 2/2] powerpc: introduce function emulate_math() Kevin Hao
0 siblings, 2 replies; 5+ messages in thread
From: Kevin Hao @ 2013-07-12 5:36 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Scott Wood; +Cc: linuxppc
v2:
Tweak the patch 2 as suggested by Benjamin and Scott.
v1:
These two patches are for the emulation of the FPU unimplemented instructions.
The first is just a bit optimization for the FPU state flush.
The second is requested by Scott.
Kevin Hao (2):
powerpc/math-emu: move the flush FPU state function into do_mathemu
powerpc: introduce function emulate_math()
arch/powerpc/kernel/traps.c | 88 +++++++++++++++++---------------------------
arch/powerpc/math-emu/math.c | 9 +++++
2 files changed, 43 insertions(+), 54 deletions(-)
--
1.8.1.4
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2 1/2] powerpc/math-emu: move the flush FPU state function into do_mathemu
2013-07-12 5:36 [PATCH v2 0/2] powerpc/math-emu: two patches for the emulation of the FPU unimplemented instructions Kevin Hao
@ 2013-07-12 5:36 ` Kevin Hao
2013-07-12 8:37 ` Benjamin Herrenschmidt
2013-07-12 5:36 ` [PATCH v2 2/2] powerpc: introduce function emulate_math() Kevin Hao
1 sibling, 1 reply; 5+ messages in thread
From: Kevin Hao @ 2013-07-12 5:36 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Scott Wood; +Cc: linuxppc
By doing this we can make sure that the FPU state is only flushed to
the thread struct when it is really needed.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
---
v2: No change.
arch/powerpc/kernel/traps.c | 9 ---------
arch/powerpc/math-emu/math.c | 9 +++++++++
2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index bf33c22..58a8065 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1131,15 +1131,6 @@ void __kprobes program_check_exception(struct pt_regs *regs)
* instruction or only on FP instructions, whether there is a
* pattern to occurrences etc. -dgibson 31/Mar/2003
*/
-
- /*
- * If we support a HW FPU, we need to ensure the FP state
- * if flushed into the thread_struct before attempting
- * emulation
- */
-#ifdef CONFIG_PPC_FPU
- flush_fp_to_thread(current);
-#endif
switch (do_mathemu(regs)) {
case 0:
emulate_single_step(regs);
diff --git a/arch/powerpc/math-emu/math.c b/arch/powerpc/math-emu/math.c
index 3fe8e35..18ce6a7 100644
--- a/arch/powerpc/math-emu/math.c
+++ b/arch/powerpc/math-emu/math.c
@@ -420,6 +420,15 @@ do_mathemu(struct pt_regs *regs)
goto illegal;
}
+ /*
+ * If we support a HW FPU, we need to ensure the FP state
+ * if flushed into the thread_struct before attempting
+ * emulation
+ */
+#ifdef CONFIG_PPC_FPU
+ flush_fp_to_thread(current);
+#endif
+
eflag = func(op0, op1, op2, op3);
if (insn & 1) {
--
1.8.1.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v2 2/2] powerpc: introduce function emulate_math()
2013-07-12 5:36 [PATCH v2 0/2] powerpc/math-emu: two patches for the emulation of the FPU unimplemented instructions Kevin Hao
2013-07-12 5:36 ` [PATCH v2 1/2] powerpc/math-emu: move the flush FPU state function into do_mathemu Kevin Hao
@ 2013-07-12 5:36 ` Kevin Hao
1 sibling, 0 replies; 5+ messages in thread
From: Kevin Hao @ 2013-07-12 5:36 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Scott Wood; +Cc: linuxppc
There are two invocations of do_mathemu() in traps.c. And the codes
in these two places are almost the same. Introduce a locale function
to eliminate the duplication. With this change we can also make sure
that in program_check_exception() the PPC_WARN_EMULATED is invoked for
the correctly emulated math instructions.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
---
v2:
* Don't depend on the FPU for the PPC_WARN_EMULATED.
* Invoke the PPC_WARN_EMULATED in the caller of do_mathemu().
* Introduce a new function to eliminate the code duplication.
arch/powerpc/kernel/traps.c | 79 +++++++++++++++++++--------------------------
1 file changed, 34 insertions(+), 45 deletions(-)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 58a8065..217724a 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1052,11 +1052,41 @@ int is_valid_bugaddr(unsigned long addr)
return is_kernel_addr(addr);
}
+#ifdef CONFIG_MATH_EMULATION
+static int emulate_math(struct pt_regs *regs)
+{
+ int ret;
+ extern int do_mathemu(struct pt_regs *regs);
+
+ ret = do_mathemu(regs);
+ if (ret >= 0)
+ PPC_WARN_EMULATED(math, regs);
+
+ switch (ret) {
+ case 0:
+ emulate_single_step(regs);
+ return 0;
+ case 1: {
+ int code = 0;
+ code = __parse_fpscr(current->thread.fpscr.val);
+ _exception(SIGFPE, regs, code, regs->nip);
+ return 0;
+ }
+ case -EFAULT:
+ _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+ return 0;
+ }
+
+ return -1;
+}
+#else
+static inline int emulate_math(struct pt_regs *regs) { return -1; }
+#endif
+
void __kprobes program_check_exception(struct pt_regs *regs)
{
enum ctx_state prev_state = exception_enter();
unsigned int reason = get_reason(regs);
- extern int do_mathemu(struct pt_regs *regs);
/* We can now get here via a FP Unavailable exception if the core
* has no FPU, in that case the reason flags will be 0 */
@@ -1122,7 +1152,6 @@ void __kprobes program_check_exception(struct pt_regs *regs)
if (!arch_irq_disabled_regs(regs))
local_irq_enable();
-#ifdef CONFIG_MATH_EMULATION
/* (reason & REASON_ILLEGAL) would be the obvious thing here,
* but there seems to be a hardware bug on the 405GP (RevD)
* that means ESR is sometimes set incorrectly - either to
@@ -1131,22 +1160,8 @@ void __kprobes program_check_exception(struct pt_regs *regs)
* instruction or only on FP instructions, whether there is a
* pattern to occurrences etc. -dgibson 31/Mar/2003
*/
- switch (do_mathemu(regs)) {
- case 0:
- emulate_single_step(regs);
- goto bail;
- case 1: {
- int code = 0;
- code = __parse_fpscr(current->thread.fpscr.val);
- _exception(SIGFPE, regs, code, regs->nip);
- goto bail;
- }
- case -EFAULT:
- _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+ if (!emulate_math(regs))
goto bail;
- }
- /* fall through on any other errors */
-#endif /* CONFIG_MATH_EMULATION */
/* Try to emulate it if we should. */
if (reason & (REASON_ILLEGAL | REASON_PRIVILEGED)) {
@@ -1425,11 +1440,6 @@ void performance_monitor_exception(struct pt_regs *regs)
#ifdef CONFIG_8xx
void SoftwareEmulation(struct pt_regs *regs)
{
- extern int do_mathemu(struct pt_regs *);
-#if defined(CONFIG_MATH_EMULATION)
- int errcode;
-#endif
-
CHECK_FULL_REGS(regs);
if (!user_mode(regs)) {
@@ -1437,31 +1447,10 @@ void SoftwareEmulation(struct pt_regs *regs)
die("Kernel Mode Software FPU Emulation", regs, SIGFPE);
}
-#ifdef CONFIG_MATH_EMULATION
- errcode = do_mathemu(regs);
- if (errcode >= 0)
- PPC_WARN_EMULATED(math, regs);
-
- switch (errcode) {
- case 0:
- emulate_single_step(regs);
- return;
- case 1: {
- int code = 0;
- code = __parse_fpscr(current->thread.fpscr.val);
- _exception(SIGFPE, regs, code, regs->nip);
- return;
- }
- case -EFAULT:
- _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+ if (!emulate_math(regs))
return;
- default:
- _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
- return;
- }
-#else
+
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
-#endif
}
#endif /* CONFIG_8xx */
--
1.8.1.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/2] powerpc/math-emu: move the flush FPU state function into do_mathemu
2013-07-12 5:36 ` [PATCH v2 1/2] powerpc/math-emu: move the flush FPU state function into do_mathemu Kevin Hao
@ 2013-07-12 8:37 ` Benjamin Herrenschmidt
2013-07-14 8:29 ` Kevin Hao
0 siblings, 1 reply; 5+ messages in thread
From: Benjamin Herrenschmidt @ 2013-07-12 8:37 UTC (permalink / raw)
To: Kevin Hao; +Cc: Scott Wood, linuxppc
On Fri, 2013-07-12 at 13:36 +0800, Kevin Hao wrote:
> + /*
> + * If we support a HW FPU, we need to ensure the FP state
> + * if flushed into the thread_struct before attempting
> + * emulation
> + */
> +#ifdef CONFIG_PPC_FPU
> + flush_fp_to_thread(current);
> +#endif
> +
While at it, care to send a patch that defined an empty
flush_fp_to_thread() in the header instead ?
ie, switch_to.h
#ifdef CONFIG_PPC_FPU
extern void flush_fp_to_thread(struct task-struct *);
#else
static inline void flush_fp_to_thread(struct task-struct *) { };
#endif
And get rid of the ifdef's here (and elsewhere if any) ?
Thanks !
Cheers,
Ben.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/2] powerpc/math-emu: move the flush FPU state function into do_mathemu
2013-07-12 8:37 ` Benjamin Herrenschmidt
@ 2013-07-14 8:29 ` Kevin Hao
0 siblings, 0 replies; 5+ messages in thread
From: Kevin Hao @ 2013-07-14 8:29 UTC (permalink / raw)
To: Benjamin Herrenschmidt; +Cc: Scott Wood, linuxppc
[-- Attachment #1: Type: text/plain, Size: 1115 bytes --]
On Fri, Jul 12, 2013 at 06:37:13PM +1000, Benjamin Herrenschmidt wrote:
> On Fri, 2013-07-12 at 13:36 +0800, Kevin Hao wrote:
> > + /*
> > + * If we support a HW FPU, we need to ensure the FP state
> > + * if flushed into the thread_struct before attempting
> > + * emulation
> > + */
> > +#ifdef CONFIG_PPC_FPU
> > + flush_fp_to_thread(current);
> > +#endif
> > +
>
> While at it, care to send a patch that defined an empty
> flush_fp_to_thread() in the header instead ?
>
> ie, switch_to.h
>
> #ifdef CONFIG_PPC_FPU
> extern void flush_fp_to_thread(struct task-struct *);
> #else
> static inline void flush_fp_to_thread(struct task-struct *) { };
> #endif
>
> And get rid of the ifdef's here (and elsewhere if any) ?
Sure. Matt also pointed out a typo in the comments of this patch.
So I will respin a v3 for this. But since I also have some similar
clean up patches as the change you just suggested, I will send them
as a separate patch series instead of messing the v3.
Thanks,
Kevin
>
> Thanks !
>
> Cheers,
> Ben.
>
>
[-- Attachment #2: Type: application/pgp-signature, Size: 490 bytes --]
^ permalink raw reply [flat|nested] 5+ messages in thread
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2013-07-12 5:36 [PATCH v2 0/2] powerpc/math-emu: two patches for the emulation of the FPU unimplemented instructions Kevin Hao
2013-07-12 5:36 ` [PATCH v2 1/2] powerpc/math-emu: move the flush FPU state function into do_mathemu Kevin Hao
2013-07-12 8:37 ` Benjamin Herrenschmidt
2013-07-14 8:29 ` Kevin Hao
2013-07-12 5:36 ` [PATCH v2 2/2] powerpc: introduce function emulate_math() Kevin Hao
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