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target/i386: fix RF handling for string instructions

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RF must be set on traps and interrupts from a string instruction,
except if they occur after the last iteration.  Ensure it is set
before giving the main loop a chance to execute.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Link: https://lore.kernel.org/r/20241215090613.89588-8-pbonzini@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2024-12-15 10:06:06 +01:00
parent 4d7704ebc5
commit 0d82d9e846
1 changed files with 21 additions and 1 deletions
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22
target/i386/tcg/translate.c
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@ -1337,6 +1337,14 @@ static void do_gen_rep(DisasContext *s, MemOp ot,
bool is_repz_nz)
{
TCGLabel *done = gen_new_label();
bool had_rf = s->flags & HF_RF_MASK;
/*
* Even if EFLAGS.RF was set on entry (such as if we're on the second or
* later iteration and an exception or interrupt happened), force gen_eob()
* not to clear the flag. We do that ourselves after the last iteration.
*/
s->flags &= ~HF_RF_MASK;
gen_update_cc_op(s);
gen_op_jz_ecx(s, done);
@ -1348,12 +1356,24 @@ static void do_gen_rep(DisasContext *s, MemOp ot,
gen_jcc(s, (JCC_Z << 1) | (nz ^ 1), done);
}
/*
* Traps or interrupts set RF_MASK if they happen after any iteration
* but the last. Set it here before giving the main loop a chance to
* execute. (For faults, seg_helper.c sets the flag as usual).
*/
if (!had_rf) {
gen_set_eflags(s, RF_MASK);
}
/* Go to the main loop but reenter the same instruction. */
gen_jmp_rel_csize(s, -cur_insn_len(s), 0);
/* CX/ECX/RCX is zero, or REPZ/REPNZ broke the repetition. */
gen_set_label(done);
set_cc_op(s, CC_OP_DYNAMIC);
if (had_rf) {
gen_reset_eflags(s, RF_MASK);
}
gen_jmp_rel_csize(s, 0, 1);
}
@ -2158,7 +2178,7 @@ gen_eob(DisasContext *s, int mode)
gen_set_hflag(s, HF_INHIBIT_IRQ_MASK);
}
if (s->base.tb->flags & HF_RF_MASK) {
if (s->flags & HF_RF_MASK) {
gen_reset_eflags(s, RF_MASK);
}
if (mode == DISAS_EOB_RECHECK_TF) {