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[10/11] target/i386: document incorrect semantics of watchpoint following MOV/POP SS

Message ID 20240604071833.962574-11-pbonzini@redhat.com (mailing list archive)
State New, archived
Headers show
Series target/i386: fixes for INHIBIT_IRQ, TF and RF | expand

Commit Message

Paolo Bonzini June 4, 2024, 7:18 a.m. UTC 
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/tcg/sysemu/bpt_helper.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Richard Henderson June 4, 2024, 1:57 p.m. UTC | #1 
On 6/4/24 02:18, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   target/i386/tcg/sysemu/bpt_helper.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/target/i386/tcg/sysemu/bpt_helper.c b/target/i386/tcg/sysemu/bpt_helper.c
> index c1d5fce250c..b29acf41c38 100644
> --- a/target/i386/tcg/sysemu/bpt_helper.c
> +++ b/target/i386/tcg/sysemu/bpt_helper.c
> @@ -215,6 +215,12 @@ void breakpoint_handler(CPUState *cs)
>           if (cs->watchpoint_hit->flags & BP_CPU) {
>               cs->watchpoint_hit = NULL;
>               if (check_hw_breakpoints(env, false)) {
> +                /*
> +                 * FIXME: #DB should be delayed by one instruction if
> +                 * INHIBIT_IRQ is set (STI cannot trigger a watchpoint).
> +                 * The delayed #DB should also fuse with one generated
> +                 * by ICEBP (aka INT1).
> +                 */
>                   raise_exception(env, EXCP01_DB);
>               } else {
>                   cpu_loop_exit_noexc(cs);

Should be fixable with some sort of state machine initiated with 
TCGCPUOps.debug_check_watchpoint, but not easy.

Acked-by: Richard Henderson <richard.henderson@linaro.org>


r~
diff mbox series

Patch

diff --git a/target/i386/tcg/sysemu/bpt_helper.c b/target/i386/tcg/sysemu/bpt_helper.c
index c1d5fce250c..b29acf41c38 100644
--- a/target/i386/tcg/sysemu/bpt_helper.c
+++ b/target/i386/tcg/sysemu/bpt_helper.c
@@ -215,6 +215,12 @@  void breakpoint_handler(CPUState *cs)
         if (cs->watchpoint_hit->flags & BP_CPU) {
             cs->watchpoint_hit = NULL;
             if (check_hw_breakpoints(env, false)) {
+                /*
+                 * FIXME: #DB should be delayed by one instruction if
+                 * INHIBIT_IRQ is set (STI cannot trigger a watchpoint).
+                 * The delayed #DB should also fuse with one generated
+                 * by ICEBP (aka INT1).
+                 */
                 raise_exception(env, EXCP01_DB);
             } else {
                 cpu_loop_exit_noexc(cs);