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target/i386: Do not re-compute new pc with CF_PCREL

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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: b5e0d5d22f ("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>
(cherry picked from commit a58506b748)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This commit is contained in:
Richard Henderson 2024-01-02 10:06:17 +11:00 committed by Michael Tokarev
parent 15e207b9ed
commit 6abbb26bbc
1 changed files with 2 additions and 4 deletions
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6
target/i386/tcg/translate.c
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@ -2883,10 +2883,6 @@ 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);
@ -2902,6 +2898,8 @@ 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)) {