83 lines
2.7 KiB
Diff
83 lines
2.7 KiB
Diff
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From 1e597afb2b3581ddcda1eeac81475452520ae43f Mon Sep 17 00:00:00 2001
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From: Julio Guerra <guerr@julio.in>
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Date: Fri, 19 Oct 2012 00:17:13 +0000
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Subject: [PATCH] PPC: Fix missing TRACE exception
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This patch fixes bug 1031698 :
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https://bugs.launchpad.net/qemu/+bug/1031698
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If we look at the (truncated) translation of the conditional branch
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instruction in the test submitted in the bug post, the call to the
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exception helper is missing in the "bne-false" chunk of translated
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code :
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IN:
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bne- 0x1800278
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OUT:
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0xb544236d: jne 0xb5442396
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0xb5442373: mov %ebp,(%esp)
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0xb5442376: mov $0x44,%ebx
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0xb544237b: mov %ebx,0x4(%esp)
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0xb544237f: mov $0x1800278,%ebx
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0xb5442384: mov %ebx,0x25c(%ebp)
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0xb544238a: call 0x827475a
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^^^^^^^^^^^^^^^^^^
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0xb5442396: mov %ebp,(%esp)
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0xb5442399: mov $0x44,%ebx
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0xb544239e: mov %ebx,0x4(%esp)
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0xb54423a2: mov $0x1800270,%ebx
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0xb54423a7: mov %ebx,0x25c(%ebp)
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Indeed, gen_exception(ctx, excp) called by gen_goto_tb (called by
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gen_bcond) changes ctx->exception's value to excp's :
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gen_bcond()
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{
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gen_goto_tb(ctx, 0, ctx->nip + li - 4);
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/* ctx->exception value is POWERPC_EXCP_BRANCH */
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gen_goto_tb(ctx, 1, ctx->nip);
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/* ctx->exception now value is POWERPC_EXCP_TRACE */
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}
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Making the following gen_goto_tb()'s test false during the second call :
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if ((ctx->singlestep_enabled &
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(CPU_BRANCH_STEP | CPU_SINGLE_STEP)) &&
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ctx->exception == POWERPC_EXCP_BRANCH /* false...*/) {
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target_ulong tmp = ctx->nip;
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ctx->nip = dest;
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/* ... and this is the missing call */
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gen_exception(ctx, POWERPC_EXCP_TRACE);
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ctx->nip = tmp;
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}
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So the patch simply adds the missing matching case, fixing our problem.
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Signed-off-by: Julio Guerra <guerr@julio.in>
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Signed-off-by: Alexander Graf <agraf@suse.de>
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(cherry picked from commit f0cc4aa8450376ca2aee3ebb09db71f9f2ff333b)
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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target-ppc/translate.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/target-ppc/translate.c b/target-ppc/translate.c
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index ac915cc..3c49ca9 100644
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--- a/target-ppc/translate.c
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+++ b/target-ppc/translate.c
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@@ -3466,7 +3466,8 @@ static inline void gen_goto_tb(DisasContext *ctx, int n, target_ulong dest)
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if (unlikely(ctx->singlestep_enabled)) {
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if ((ctx->singlestep_enabled &
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(CPU_BRANCH_STEP | CPU_SINGLE_STEP)) &&
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- ctx->exception == POWERPC_EXCP_BRANCH) {
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+ (ctx->exception == POWERPC_EXCP_BRANCH ||
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+ ctx->exception == POWERPC_EXCP_TRACE)) {
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target_ulong tmp = ctx->nip;
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ctx->nip = dest;
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gen_exception(ctx, POWERPC_EXCP_TRACE);
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