Re: [PATCH v2 17/19] tcg: save vaddr temp for plugin usage

[Emilio G. Cota]

On Thu, Feb 13, 2020 at 22:51:07 +, Alex Bennée wrote:
> From: Richard Henderson 
> 
> While do_gen_mem_cb does copy (via extu_tl_i64) vaddr into a new temp
> this won't help if the vaddr temp gets clobbered by the actual
> load/store op. To avoid this clobbering we explicitly copy vaddr
> before the op to ensure it is live my the time we do the
> instrumentation.

s/my the time/by the time/

Reviewed-by: Emilio G. Cota 

E.

Re: [PATCH v2 17/19] tcg: save vaddr temp for plugin usage

[Richard Henderson]

On 2/13/20 2:51 PM, Alex Bennée wrote:
> From: Richard Henderson 
> 
> While do_gen_mem_cb does copy (via extu_tl_i64) vaddr into a new temp
> this won't help if the vaddr temp gets clobbered by the actual
> load/store op. To avoid this clobbering we explicitly copy vaddr
> before the op to ensure it is live my the time we do the
> instrumentation.
> 
> Suggested-by: Richard Henderson 
> Signed-off-by: Alex Bennée 
> Cc: qemu-sta...@nongnu.org
> ---
>  tcg/tcg-op.c | 23 ---
>  1 file changed, 20 insertions(+), 3 deletions(-)

Reviewed-by: Richard Henderson 

r~

[PATCH v2 17/19] tcg: save vaddr temp for plugin usage

[Alex Bennée]

From: Richard Henderson 

While do_gen_mem_cb does copy (via extu_tl_i64) vaddr into a new temp
this won't help if the vaddr temp gets clobbered by the actual
load/store op. To avoid this clobbering we explicitly copy vaddr
before the op to ensure it is live my the time we do the
instrumentation.

Suggested-by: Richard Henderson 
Signed-off-by: Alex Bennée 
Cc: qemu-sta...@nongnu.org
---
 tcg/tcg-op.c | 23 ---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index 7d782002e3f..e2e25ebf7db 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -2794,13 +2794,26 @@ static void tcg_gen_req_mo(TCGBar type)
 }
 }
 
+static inline TCGv plugin_prep_mem_callbacks(TCGv vaddr)
+{
+#ifdef CONFIG_PLUGIN
+if (tcg_ctx->plugin_insn != NULL) {
+/* Save a copy of the vaddr for use after a load.  */
+TCGv temp = tcg_temp_new();
+tcg_gen_mov_tl(temp, vaddr);
+return temp;
+}
+#endif
+return vaddr;
+}
+
 static inline void plugin_gen_mem_callbacks(TCGv vaddr, uint16_t info)
 {
 #ifdef CONFIG_PLUGIN
-if (tcg_ctx->plugin_insn == NULL) {
-return;
+if (tcg_ctx->plugin_insn != NULL) {
+plugin_gen_empty_mem_callback(vaddr, info);
+tcg_temp_free(vaddr);
 }
-plugin_gen_empty_mem_callback(vaddr, info);
 #endif
 }
 
@@ -2822,6 +2835,7 @@ void tcg_gen_qemu_ld_i32(TCGv_i32 val, TCGv addr, TCGArg 
idx, MemOp memop)
 }
 }
 
+addr = plugin_prep_mem_callbacks(addr);
 gen_ldst_i32(INDEX_op_qemu_ld_i32, val, addr, memop, idx);
 plugin_gen_mem_callbacks(addr, info);
 
@@ -2868,6 +2882,7 @@ void tcg_gen_qemu_st_i32(TCGv_i32 val, TCGv addr, TCGArg 
idx, MemOp memop)
 memop &= ~MO_BSWAP;
 }
 
+addr = plugin_prep_mem_callbacks(addr);
 gen_ldst_i32(INDEX_op_qemu_st_i32, val, addr, memop, idx);
 plugin_gen_mem_callbacks(addr, info);
 
@@ -2905,6 +2920,7 @@ void tcg_gen_qemu_ld_i64(TCGv_i64 val, TCGv addr, TCGArg 
idx, MemOp memop)
 }
 }
 
+addr = plugin_prep_mem_callbacks(addr);
 gen_ldst_i64(INDEX_op_qemu_ld_i64, val, addr, memop, idx);
 plugin_gen_mem_callbacks(addr, info);
 
@@ -2967,6 +2983,7 @@ void tcg_gen_qemu_st_i64(TCGv_i64 val, TCGv addr, TCGArg 
idx, MemOp memop)
 memop &= ~MO_BSWAP;
 }
 
+addr = plugin_prep_mem_callbacks(addr);
 gen_ldst_i64(INDEX_op_qemu_st_i64, val, addr, memop, idx);
 plugin_gen_mem_callbacks(addr, info);
 
-- 
2.20.1