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target/ppc: Suppress single step interrupts on rfi-type instructions 

BookS does not take single step interrupts on completion of rfi and
similar (rfid, hrfid, rfscv). This is not a completely clean way to
do it, but in general non-branch instructions that change NIP on
completion are excluded.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
This commit is contained in:
Nicholas Piggin 2023-08-08 13:11:13 +10:00 committed by Cédric Le Goater
parent 148953849d
commit a11e3a1582
1 changed files with 17 additions and 6 deletions
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23
target/ppc/translate.c
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@ -336,7 +336,7 @@ static void gen_ppc_maybe_interrupt(DisasContext *ctx)
* The exception can be either POWERPC_EXCP_TRACE (on most PowerPCs) or
* POWERPC_EXCP_DEBUG (on BookE).
*/
static void gen_debug_exception(DisasContext *ctx)
static void gen_debug_exception(DisasContext *ctx, bool rfi_type)
{
#if !defined(CONFIG_USER_ONLY)
if (ctx->flags & POWERPC_FLAG_DE) {
@ -355,10 +355,12 @@ static void gen_debug_exception(DisasContext *ctx)
tcg_constant_i32(POWERPC_EXCP_DEBUG));
ctx->base.is_jmp = DISAS_NORETURN;
} else {
TCGv t0 = tcg_temp_new();
tcg_gen_movi_tl(t0, ctx->cia);
gen_helper_book3s_trace(cpu_env, t0);
ctx->base.is_jmp = DISAS_NORETURN;
if (!rfi_type) { /* BookS does not single step rfi type instructions */
TCGv t0 = tcg_temp_new();
tcg_gen_movi_tl(t0, ctx->cia);
gen_helper_book3s_trace(cpu_env, t0);
ctx->base.is_jmp = DISAS_NORETURN;
}
}
#endif
}
@ -7410,6 +7412,8 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, CPUState *cs)
/* Honor single stepping. */
if (unlikely(ctx->singlestep_enabled & CPU_SINGLE_STEP)) {
bool rfi_type = false;
switch (is_jmp) {
case DISAS_TOO_MANY:
case DISAS_EXIT_UPDATE:
@ -7418,12 +7422,19 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, CPUState *cs)
break;
case DISAS_EXIT:
case DISAS_CHAIN:
/*
* This is a heuristic, to put it kindly. The rfi class of
* instructions are among the few outside branches that change
* NIP without taking an interrupt. Single step trace interrupts
* do not fire on completion of these instructions.
*/
rfi_type = true;
break;
default:
g_assert_not_reached();
}
gen_debug_exception(ctx);
gen_debug_exception(ctx, rfi_type);
return;
}