[PATCH] target/xtensa: statically allocate xtensa_insnbufs in DisasContext

[PATCH] target/xtensa: statically allocate xtensa_insnbufs in DisasContext

[Max Filippov]

Rather than dynamically allocate, and risk failing to free
when we longjmp out of the translator, allocate the maximum
buffer size based on the maximum supported instruction length.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 target/xtensa/cpu.h       |  3 +++
 target/xtensa/helper.c    |  1 +
 target/xtensa/translate.c | 17 ++---------------
 3 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/target/xtensa/cpu.h b/target/xtensa/cpu.h
index c0d69fad96c5..7a46dccbe11b 100644
--- a/target/xtensa/cpu.h
+++ b/target/xtensa/cpu.h
@@ -213,6 +213,9 @@ enum {
 #define MEMCTL_IL0EN 0x1
 
 #define MAX_INSN_LENGTH 64
+#define MAX_INSNBUF_LENGTH \
+    ((MAX_INSN_LENGTH + sizeof(xtensa_insnbuf_word) - 1) / \
+     sizeof(xtensa_insnbuf_word))
 #define MAX_INSN_SLOTS 32
 #define MAX_OPCODE_ARGS 16
 #define MAX_NAREG 64
diff --git a/target/xtensa/helper.c b/target/xtensa/helper.c
index 376a61f3397c..7073381f03b2 100644
--- a/target/xtensa/helper.c
+++ b/target/xtensa/helper.c
@@ -96,6 +96,7 @@ static void init_libisa(XtensaConfig *config)
 
     config->isa = xtensa_isa_init(config->isa_internal, NULL, NULL);
     assert(xtensa_isa_maxlength(config->isa) <= MAX_INSN_LENGTH);
+    assert(xtensa_insnbuf_size(config->isa) <= MAX_INSNBUF_LENGTH);
     opcodes = xtensa_isa_num_opcodes(config->isa);
     formats = xtensa_isa_num_formats(config->isa);
     regfiles = xtensa_isa_num_regfiles(config->isa);
diff --git a/target/xtensa/translate.c b/target/xtensa/translate.c
index 37f65b1f0305..91c7776c2544 100644
--- a/target/xtensa/translate.c
+++ b/target/xtensa/translate.c
@@ -72,8 +72,8 @@ struct DisasContext {
     unsigned cpenable;
 
     uint32_t op_flags;
-    xtensa_insnbuf insnbuf;
-    xtensa_insnbuf slotbuf;
+    xtensa_insnbuf_word insnbuf[MAX_INSNBUF_LENGTH];
+    xtensa_insnbuf_word slotbuf[MAX_INSNBUF_LENGTH];
 };
 
 static TCGv_i32 cpu_pc;
@@ -1174,15 +1174,6 @@ static void xtensa_tr_init_disas_context(DisasContextBase *dcbase,
     dc->callinc = ((tb_flags & XTENSA_TBFLAG_CALLINC_MASK) >>
                    XTENSA_TBFLAG_CALLINC_SHIFT);
 
-    /*
-     * FIXME: This will leak when a failed instruction load or similar
-     * event causes us to longjump out of the translation loop and
-     * hence not clean-up in xtensa_tr_tb_stop
-     */
-    if (dc->config->isa) {
-        dc->insnbuf = xtensa_insnbuf_alloc(dc->config->isa);
-        dc->slotbuf = xtensa_insnbuf_alloc(dc->config->isa);
-    }
     init_sar_tracker(dc);
 }
 
@@ -1272,10 +1263,6 @@ static void xtensa_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
     DisasContext *dc = container_of(dcbase, DisasContext, base);
 
     reset_sar_tracker(dc);
-    if (dc->config->isa) {
-        xtensa_insnbuf_free(dc->config->isa, dc->insnbuf);
-        xtensa_insnbuf_free(dc->config->isa, dc->slotbuf);
-    }
     if (dc->icount) {
         tcg_temp_free(dc->next_icount);
     }
-- 
2.20.1

Re: [PATCH] target/xtensa: statically allocate xtensa_insnbufs in DisasContext

[Richard Henderson]

On 4/7/20 12:09 PM, Max Filippov wrote:
> Rather than dynamically allocate, and risk failing to free
> when we longjmp out of the translator, allocate the maximum
> buffer size based on the maximum supported instruction length.
> 
> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
> ---
>  target/xtensa/cpu.h       |  3 +++
>  target/xtensa/helper.c    |  1 +
>  target/xtensa/translate.c | 17 ++---------------
>  3 files changed, 6 insertions(+), 15 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by:  Richard Henderson <richard.henderson@linaro.org>


r~