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accel/tcg: Record singlestep_enabled in tb->cflags 

Set CF_SINGLE_STEP when single-stepping is enabled.
This avoids the need to flush all tb's when turning
single-stepping on or off.

Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2021-07-19 10:43:46 -10:00
parent d40c5c7976
commit c2ffd7549b
5 changed files with 8 additions and 15 deletions
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7
accel/tcg/cpu-exec.c
View File

@ -150,10 +150,15 @@ uint32_t curr_cflags(CPUState *cpu)
uint32_t cflags = cpu->tcg_cflags;
/*
* Record gdb single-step. We should be exiting the TB by raising
* EXCP_DEBUG, but to simplify other tests, disable chaining too.
*
* For singlestep and -d nochain, suppress goto_tb so that
* we can log -d cpu,exec after every TB.
*/
if (singlestep) {
if (unlikely(cpu->singlestep_enabled)) {
cflags |= CF_NO_GOTO_TB | CF_NO_GOTO_PTR | CF_SINGLE_STEP | 1;
} else if (singlestep) {
cflags |= CF_NO_GOTO_TB | 1;
} else if (qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
cflags |= CF_NO_GOTO_TB;

4
accel/tcg/translate-all.c
View File

@ -1432,10 +1432,6 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
}
QEMU_BUILD_BUG_ON(CF_COUNT_MASK + 1 != TCG_MAX_INSNS);
if (cpu->singlestep_enabled) {
max_insns = 1;
}
buffer_overflow:
tb = tcg_tb_alloc(tcg_ctx);
if (unlikely(!tb)) {

7
accel/tcg/translator.c
View File

@ -38,11 +38,6 @@ bool translator_use_goto_tb(DisasContextBase *db, target_ulong dest)
return false;
}
/* Suppress goto_tb in the case of single-steping. */
if (db->singlestep_enabled) {
return false;
}
/* Check for the dest on the same page as the start of the TB. */
return ((db->pc_first ^ dest) & TARGET_PAGE_MASK) == 0;
}
@ -60,7 +55,7 @@ void translator_loop(const TranslatorOps *ops, DisasContextBase *db,
db->is_jmp = DISAS_NEXT;
db->num_insns = 0;
db->max_insns = max_insns;
db->singlestep_enabled = cpu->singlestep_enabled;
db->singlestep_enabled = cflags & CF_SINGLE_STEP;
ops->init_disas_context(db, cpu);
tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */

4
cpu.c
View File

@ -326,10 +326,6 @@ void cpu_single_step(CPUState *cpu, int enabled)
cpu->singlestep_enabled = enabled;
if (kvm_enabled()) {
kvm_update_guest_debug(cpu, 0);
} else {
/* must flush all the translated code to avoid inconsistencies */
/* XXX: only flush what is necessary */
tb_flush(cpu);
}
trace_breakpoint_singlestep(cpu->cpu_index, enabled);
}

1
include/exec/exec-all.h
View File

@ -497,6 +497,7 @@ struct TranslationBlock {
#define CF_COUNT_MASK 0x000001ff
#define CF_NO_GOTO_TB 0x00000200 /* Do not chain with goto_tb */
#define CF_NO_GOTO_PTR 0x00000400 /* Do not chain with goto_ptr */
#define CF_SINGLE_STEP 0x00000800 /* gdbstub single-step in effect */
#define CF_LAST_IO 0x00008000 /* Last insn may be an IO access. */
#define CF_MEMI_ONLY 0x00010000 /* Only instrument memory ops */
#define CF_USE_ICOUNT 0x00020000