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| author | Richard Henderson <richard.henderson@linaro.org> | 2024-01-02 10:06:17 +1100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2024-01-18 10:43:14 +0100 |
| commit | a58506b748b8988a95f4fa1a2420ac5c17038b30 (patch) | |
| tree | 4daced2875bac1086aa2050dc2e87e3d566de520 | |
| parent | 3cbc17ee92479ff56d0d6afecc0def6f7ec01153 (diff) | |
| download | qemu-a58506b748b8988a95f4fa1a2420ac5c17038b30.zip qemu-a58506b748b8988a95f4fa1a2420ac5c17038b30.tar.gz qemu-a58506b748b8988a95f4fa1a2420ac5c17038b30.tar.bz2 | |
target/i386: Do not re-compute new pc with CF_PCREL
With PCREL, we have a page-relative view of EIP, and an
approximation of PC = EIP+CSBASE that is good enough to
detect page crossings. If we try to recompute PC after
masking EIP, we will mess up that approximation and write
a corrupt value to EIP.
We already handled masking properly for PCREL, so the
fix in b5e0d5d2 was only needed for the !PCREL path.
Cc: qemu-stable@nongnu.org
Fixes: b5e0d5d22fbf ("target/i386: Fix 32-bit wrapping of pc/eip computation")
Reported-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240101230617.129349-1-richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | target/i386/tcg/translate.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index e1eb82a..d4d7e90 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -2866,10 +2866,6 @@ static void gen_jmp_rel(DisasContext *s, MemOp ot, int diff, int tb_num) } } new_eip &= mask; - new_pc = new_eip + s->cs_base; - if (!CODE64(s)) { - new_pc = (uint32_t)new_pc; - } gen_update_cc_op(s); set_cc_op(s, CC_OP_DYNAMIC); @@ -2885,6 +2881,8 @@ static void gen_jmp_rel(DisasContext *s, MemOp ot, int diff, int tb_num) tcg_gen_andi_tl(cpu_eip, cpu_eip, mask); use_goto_tb = false; } + } else if (!CODE64(s)) { + new_pc = (uint32_t)(new_eip + s->cs_base); } if (use_goto_tb && translator_use_goto_tb(&s->base, new_pc)) { |