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[Qemu-devel] [PATCH 2/6] PPC: Fix missing TRACE exception
From: |
Alexander Graf |
Subject: |
[Qemu-devel] [PATCH 2/6] PPC: Fix missing TRACE exception |
Date: |
Mon, 26 Nov 2012 19:55:53 +0100 |
From: Julio Guerra <address@hidden>
This patch fixes bug 1031698 :
https://bugs.launchpad.net/qemu/+bug/1031698
If we look at the (truncated) translation of the conditional branch
instruction in the test submitted in the bug post, the call to the
exception helper is missing in the "bne-false" chunk of translated
code :
IN:
bne- 0x1800278
OUT:
0xb544236d: jne 0xb5442396
0xb5442373: mov %ebp,(%esp)
0xb5442376: mov $0x44,%ebx
0xb544237b: mov %ebx,0x4(%esp)
0xb544237f: mov $0x1800278,%ebx
0xb5442384: mov %ebx,0x25c(%ebp)
0xb544238a: call 0x827475a
^^^^^^^^^^^^^^^^^^
0xb5442396: mov %ebp,(%esp)
0xb5442399: mov $0x44,%ebx
0xb544239e: mov %ebx,0x4(%esp)
0xb54423a2: mov $0x1800270,%ebx
0xb54423a7: mov %ebx,0x25c(%ebp)
Indeed, gen_exception(ctx, excp) called by gen_goto_tb (called by
gen_bcond) changes ctx->exception's value to excp's :
gen_bcond()
{
gen_goto_tb(ctx, 0, ctx->nip + li - 4);
/* ctx->exception value is POWERPC_EXCP_BRANCH */
gen_goto_tb(ctx, 1, ctx->nip);
/* ctx->exception now value is POWERPC_EXCP_TRACE */
}
Making the following gen_goto_tb()'s test false during the second call :
if ((ctx->singlestep_enabled &
(CPU_BRANCH_STEP | CPU_SINGLE_STEP)) &&
ctx->exception == POWERPC_EXCP_BRANCH /* false...*/) {
target_ulong tmp = ctx->nip;
ctx->nip = dest;
/* ... and this is the missing call */
gen_exception(ctx, POWERPC_EXCP_TRACE);
ctx->nip = tmp;
}
So the patch simply adds the missing matching case, fixing our problem.
Signed-off-by: Julio Guerra <address@hidden>
Signed-off-by: Alexander Graf <address@hidden>
---
target-ppc/translate.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 16b9c5d..987b04e 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -3473,7 +3473,8 @@ static inline void gen_goto_tb(DisasContext *ctx, int n,
target_ulong dest)
if (unlikely(ctx->singlestep_enabled)) {
if ((ctx->singlestep_enabled &
(CPU_BRANCH_STEP | CPU_SINGLE_STEP)) &&
- ctx->exception == POWERPC_EXCP_BRANCH) {
+ (ctx->exception == POWERPC_EXCP_BRANCH ||
+ ctx->exception == POWERPC_EXCP_TRACE)) {
target_ulong tmp = ctx->nip;
ctx->nip = dest;
gen_exception(ctx, POWERPC_EXCP_TRACE);
--
1.6.0.2
- [Qemu-devel] [PULL 1.3 0/6] ppc 1.3 patch queue 2012-11-26, Alexander Graf, 2012/11/26
- [Qemu-devel] [PATCH 3/6] kvm: fix incorrect length in a loop over kvm dirty pages map, Alexander Graf, 2012/11/26
- [Qemu-devel] [PATCH 1/6] hw/ide/macio: Fix segfault caused by NULL DMAContext*, Alexander Graf, 2012/11/26
- [Qemu-devel] [PATCH 6/6] fbdev: fix pixman compile on old pixman, Alexander Graf, 2012/11/26
- [Qemu-devel] [PATCH 4/6] pseries: Fix bug in PCI MSI allocation, Alexander Graf, 2012/11/26
- [Qemu-devel] [PATCH 2/6] PPC: Fix missing TRACE exception,
Alexander Graf <=
- [Qemu-devel] [PATCH 5/6] vl.c: Fix broken -usb option, Alexander Graf, 2012/11/26
- Re: [Qemu-devel] [PULL 1.3 0/6] ppc 1.3 patch queue 2012-11-26, Anthony Liguori, 2012/11/28