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authorRichard Henderson <rth@twiddle.net>2015-09-18 23:43:05 -0700
committerRichard Henderson <rth@twiddle.net>2015-10-07 20:36:53 +1100
commit8163b74938d8b7d12e70597c4553dd0dc49443d5 (patch)
tree8cac7a8219d3e650cd0f9854fb62a73385383558 /translate-all.c
parent04fe64000162c45d8974da9ca4d266f8d0e67eb7 (diff)
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tcg: Emit prologue to the beginning of code_gen_buffer
By putting the prologue at the end, we risk overwriting the prologue should our estimate of maximum TB size. Given the two different placements of the call to tcg_prologue_init, move the high water mark computation into tcg_prologue_init. Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'translate-all.c')
-rw-r--r--translate-all.c28
1 files changed, 9 insertions, 19 deletions
diff --git a/translate-all.c b/translate-all.c
index 3454f4e..0e8d176 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -690,23 +690,15 @@ static inline void code_gen_alloc(size_t tb_size)
}
qemu_madvise(tcg_ctx.code_gen_buffer, tcg_ctx.code_gen_buffer_size,
- QEMU_MADV_HUGEPAGE);
-
- /* Steal room for the prologue at the end of the buffer. This ensures
- (via the MAX_CODE_GEN_BUFFER_SIZE limits above) that direct branches
- from TB's to the prologue are going to be in range. It also means
- that we don't need to mark (additional) portions of the data segment
- as executable. */
- tcg_ctx.code_gen_prologue = tcg_ctx.code_gen_buffer +
- tcg_ctx.code_gen_buffer_size - 1024;
- tcg_ctx.code_gen_buffer_size -= 1024;
-
- tcg_ctx.code_gen_buffer_max_size = tcg_ctx.code_gen_buffer_size -
- (TCG_MAX_OP_SIZE * OPC_BUF_SIZE);
- tcg_ctx.code_gen_max_blocks = tcg_ctx.code_gen_buffer_size /
- CODE_GEN_AVG_BLOCK_SIZE;
- tcg_ctx.tb_ctx.tbs =
- g_malloc(tcg_ctx.code_gen_max_blocks * sizeof(TranslationBlock));
+ QEMU_MADV_HUGEPAGE);
+
+ /* Estimate a good size for the number of TBs we can support. We
+ still haven't deducted the prologue from the buffer size here,
+ but that's minimal and won't affect the estimate much. */
+ tcg_ctx.code_gen_max_blocks
+ = tcg_ctx.code_gen_buffer_size / CODE_GEN_AVG_BLOCK_SIZE;
+ tcg_ctx.tb_ctx.tbs = g_new(TranslationBlock, tcg_ctx.code_gen_max_blocks);
+
qemu_mutex_init(&tcg_ctx.tb_ctx.tb_lock);
}
@@ -717,8 +709,6 @@ void tcg_exec_init(unsigned long tb_size)
{
cpu_gen_init();
code_gen_alloc(tb_size);
- tcg_ctx.code_gen_ptr = tcg_ctx.code_gen_buffer;
- tcg_register_jit(tcg_ctx.code_gen_buffer, tcg_ctx.code_gen_buffer_size);
page_init();
#if defined(CONFIG_SOFTMMU)
/* There's no guest base to take into account, so go ahead and