On 7/21/21 12:38 AM, Alex Bennée wrote:
Richard Henderson <richard.hender...@linaro.org> writes:
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.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
include/exec/exec-all.h | 1 +
accel/tcg/cpu-exec.c | 7 ++++++-
accel/tcg/translate-all.c | 4 ----
accel/tcg/translator.c | 7 +------
cpu.c | 4 ----
5 files changed, 8 insertions(+), 15 deletions(-)
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 6873cce8df..5d1b6d80fb 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -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
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 5cc6363f4c..fc895cf51e 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -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;
What does CF_SINGLE_STEP achieve that isn't already handled by having:
cflags |= CF_NO_GOTO_TB | CF_NO_GOTO_PTR | 1;
It sets DisasContextBase.singlestep_enabled.
With only this patch set, we still check that and emit EXCP_DEBUG at the end of every TB.
After the 6.2 singlestep cleanup, we still have one reference to
DisasContextBase.singlestep_enabled in target/mips for the branch delay slot thing that we
discussed on IRC yesterday.
(btw did we mask CF_COUNT_MASK somewhere else?). Because surely the
CF_COUNT is part of cflags so limits the TB's that could be returned
anyway?
Here in curr_cflags(), CF_COUNT_MASK begins at zero.
r~
