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[PULL 1/8] accel/tcg: introduce CF_NOIRQ
From: |
Alex Bennée |
Subject: |
[PULL 1/8] accel/tcg: introduce CF_NOIRQ |
Date: |
Mon, 29 Nov 2021 17:14:42 +0000 |
Here we introduce a new compiler flag to disable the checking of exit
request (icount_decr.u32). This is useful when we want to ensure the
next block cannot be preempted by an asynchronous event.
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211129140932.4115115-2-alex.bennee@linaro.org>
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 6bb2a0f7ec..35d8e93976 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -503,6 +503,7 @@ struct TranslationBlock {
#define CF_USE_ICOUNT 0x00020000
#define CF_INVALID 0x00040000 /* TB is stale. Set with @jmp_lock held */
#define CF_PARALLEL 0x00080000 /* Generate code for a parallel context */
+#define CF_NOIRQ 0x00100000 /* Generate an uninterruptible TB */
#define CF_CLUSTER_MASK 0xff000000 /* Top 8 bits are cluster ID */
#define CF_CLUSTER_SHIFT 24
diff --git a/include/exec/gen-icount.h b/include/exec/gen-icount.h
index 610cba58fe..c57204ddad 100644
--- a/include/exec/gen-icount.h
+++ b/include/exec/gen-icount.h
@@ -21,7 +21,6 @@ static inline void gen_tb_start(const TranslationBlock *tb)
{
TCGv_i32 count;
- tcg_ctx->exitreq_label = gen_new_label();
if (tb_cflags(tb) & CF_USE_ICOUNT) {
count = tcg_temp_local_new_i32();
} else {
@@ -42,7 +41,19 @@ static inline void gen_tb_start(const TranslationBlock *tb)
icount_start_insn = tcg_last_op();
}
- tcg_gen_brcondi_i32(TCG_COND_LT, count, 0, tcg_ctx->exitreq_label);
+ /*
+ * Emit the check against icount_decr.u32 to see if we should exit
+ * unless we suppress the check with CF_NOIRQ. If we are using
+ * icount and have suppressed interruption the higher level code
+ * should have ensured we don't run more instructions than the
+ * budget.
+ */
+ if (tb_cflags(tb) & CF_NOIRQ) {
+ tcg_ctx->exitreq_label = NULL;
+ } else {
+ tcg_ctx->exitreq_label = gen_new_label();
+ tcg_gen_brcondi_i32(TCG_COND_LT, count, 0, tcg_ctx->exitreq_label);
+ }
if (tb_cflags(tb) & CF_USE_ICOUNT) {
tcg_gen_st16_i32(count, cpu_env,
@@ -74,8 +85,10 @@ static inline void gen_tb_end(const TranslationBlock *tb,
int num_insns)
tcgv_i32_arg(tcg_constant_i32(num_insns)));
}
- gen_set_label(tcg_ctx->exitreq_label);
- tcg_gen_exit_tb(tb, TB_EXIT_REQUESTED);
+ if (tcg_ctx->exitreq_label) {
+ gen_set_label(tcg_ctx->exitreq_label);
+ tcg_gen_exit_tb(tb, TB_EXIT_REQUESTED);
+ }
}
#endif
--
2.30.2
- [PULL for 6.2 0/8] more tcg, plugin, test and build fixes, Alex Bennée, 2021/11/29
- [PULL 1/8] accel/tcg: introduce CF_NOIRQ,
Alex Bennée <=
- [PULL 2/8] accel/tcg: suppress IRQ check for special TBs, Alex Bennée, 2021/11/29
- [PULL 4/8] plugins/meson.build: fix linker issue with weird paths, Alex Bennée, 2021/11/29
- [PULL 5/8] gdbstub: handle a potentially racing TaskState, Alex Bennée, 2021/11/29
- [PULL 3/8] tests/avocado: fix tcg_plugin mem access count test, Alex Bennée, 2021/11/29
- [PULL 6/8] MAINTAINERS: Remove me as a reviewer for the build and test/avocado, Alex Bennée, 2021/11/29
- [PULL 7/8] MAINTAINERS: Add section for Aarch64 GitLab custom runner, Alex Bennée, 2021/11/29
- [PULL 8/8] tests/plugin/syscall.c: fix compiler warnings, Alex Bennée, 2021/11/29
- Re: [PULL for 6.2 0/8] more tcg, plugin, test and build fixes, Richard Henderson, 2021/11/29