From 5fad293bcbd48d9a2370020cf60e4b4a42559b12 Mon Sep 17 00:00:00 2001
From: Kumar Gala <galak@kernel.crashing.org>
Date: Wed, 7 Feb 2007 01:47:59 -0600
Subject: [POWERPC] Fixup error handling when emulating a floating point
instruction
When we do full FP emulation its possible that we need to post a SIGFPE based
on the results of the emulation. The previous code ignored this case completely.
Additionally, the Soft_emulate_8xx case had two issues. One, we should never
generate a SIGFPE since the code only does data movement. Second, we were
interpreting the return codes incorrectly, it returns 0 on success, 1 on
illop and -EFAULT on a data access error.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
---
arch/powerpc/kernel/traps.c | 82 +++++++++++++++++++++++++++++++++------------
1 file changed, 60 insertions(+), 22 deletions(-)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index f038caa3c2b..dcc6f159fd9 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -535,34 +535,40 @@ static void emulate_single_step(struct pt_regs *regs)
}
}
-static void parse_fpe(struct pt_regs *regs)
+static inline int __parse_fpscr(unsigned long fpscr)
{
- int code = 0;
- unsigned long fpscr;
-
- flush_fp_to_thread(current);
-
- fpscr = current->thread.fpscr.val;
+ int ret = 0;
/* Invalid operation */
if ((fpscr & FPSCR_VE) && (fpscr & FPSCR_VX))
- code = FPE_FLTINV;
+ ret = FPE_FLTINV;
/* Overflow */
else if ((fpscr & FPSCR_OE) && (fpscr & FPSCR_OX))
- code = FPE_FLTOVF;
+ ret = FPE_FLTOVF;
/* Underflow */
else if ((fpscr & FPSCR_UE) && (fpscr & FPSCR_UX))
- code = FPE_FLTUND;
+ ret = FPE_FLTUND;
/* Divide by zero */
else if ((fpscr & FPSCR_ZE) && (fpscr & FPSCR_ZX))
- code = FPE_FLTDIV;
+ ret = FPE_FLTDIV;
/* Inexact result */
else if ((fpscr & FPSCR_XE) && (fpscr & FPSCR_XX))
- code = FPE_FLTRES;
+ ret = FPE_FLTRES;
+
+ return ret;
+}
+
+static void parse_fpe(struct pt_regs *regs)
+{
+ int code = 0;
+
+ flush_fp_to_thread(current);
+
+ code = __parse_fpscr(current->thread.fpscr.val);
_exception(SIGFPE, regs, code, regs->nip);
}
@@ -773,10 +779,21 @@ void __kprobes program_check_exception(struct pt_regs *regs)
* hardware people - not sure if it can happen on any illegal
* instruction or only on FP instructions, whether there is a
* pattern to occurences etc. -dgibson 31/Mar/2003 */
- if (do_mathemu(regs) == 0) {
+ switch (do_mathemu(regs)) {
+ 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);
+ return;
}
+ /* fall through on any other errors */
#endif /* CONFIG_MATH_EMULATION */
/* Try to emulate it if we should. */
@@ -892,18 +909,39 @@ void SoftwareEmulation(struct pt_regs *regs)
#ifdef CONFIG_MATH_EMULATION
errcode = do_mathemu(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);
+ return;
+ default:
+ _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
+ return;
+ }
+
#else
errcode = Soft_emulate_8xx(regs);
-#endif
- if (errcode) {
- if (errcode > 0)
- _exception(SIGFPE, regs, 0, 0);
- else if (errcode == -EFAULT)
- _exception(SIGSEGV, regs, 0, 0);
- else
- _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
- } else
+ switch (errcode) {
+ case 0:
emulate_single_step(regs);
+ return;
+ case 1:
+ _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
+ return;
+ case -EFAULT:
+ _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+ return;
+ }
+#endif
}
#endif /* CONFIG_8xx */
--
cgit v1.2.3-18-g5258