[for-7.1,1/5] target/loongarch: Fix GDB get the wrong pc

Commit Message

gaosong Aug. 4, 2022, 1:02 p.m. UTC

GDB LoongArch add a register orig_a0, see the base64.xml [1].
We should add the orig_a0 to match the upstream GDB.

[1]: https://github.com/bminor/binutils-gdb/blob/master/gdb/features/loongarch/base64.xml

Signed-off-by: Song Gao <[e-mail]>
---
 gdb-xml/loongarch-base64.xml | 1 +
 target/loongarch/cpu.c       | 2 +-
 target/loongarch/gdbstub.c   | 7 +++++--
 3 files changed, 7 insertions(+), 3 deletions(-)

Comments

Richard Henderson Aug. 4, 2022, 3:56 p.m. UTC | #1

On 8/4/22 06:02, Song Gao wrote:
> +        /* orig_a0 */
> +        return gdb_get_regl(mem_buf, env->gpr[4]);

There is no rational value to provide for orig_a0,
because this is only related to the linux kernel.
I understand that you need to enumerate the register
so that pc gets number 35, but you might as well
simply provide zero for this value.


r~

Patch

diff --git a/gdb-xml/loongarch-base64.xml b/gdb-xml/loongarch-base64.xml
index 4962bdbd28..a1dd4f2208 100644
--- a/gdb-xml/loongarch-base64.xml
+++ b/gdb-xml/loongarch-base64.xml
@@ -39,6 +39,7 @@ 
   <reg name="r29" bitsize="64" type="uint64" group="general"/>
   <reg name="r30" bitsize="64" type="uint64" group="general"/>
   <reg name="r31" bitsize="64" type="uint64" group="general"/>
+  <reg name="orig_a0" bitsize="64" type="uint64" group="general"/>
   <reg name="pc" bitsize="64" type="code_ptr" group="general"/>
   <reg name="badvaddr" bitsize="64" type="code_ptr" group="general"/>
 </feature>
diff --git a/target/loongarch/cpu.c b/target/loongarch/cpu.c
index 1c69a76f2b..d84ec38cf7 100644
--- a/target/loongarch/cpu.c
+++ b/target/loongarch/cpu.c
@@ -683,7 +683,7 @@  static void loongarch_cpu_class_init(ObjectClass *c, void *data)
     cc->gdb_read_register = loongarch_cpu_gdb_read_register;
     cc->gdb_write_register = loongarch_cpu_gdb_write_register;
     cc->disas_set_info = loongarch_cpu_disas_set_info;
-    cc->gdb_num_core_regs = 34;
+    cc->gdb_num_core_regs = 35;
     cc->gdb_core_xml_file = "loongarch-base64.xml";
     cc->gdb_stop_before_watchpoint = true;
 
diff --git a/target/loongarch/gdbstub.c b/target/loongarch/gdbstub.c
index 24e126fb2d..e643eca2d5 100644
--- a/target/loongarch/gdbstub.c
+++ b/target/loongarch/gdbstub.c
@@ -19,8 +19,11 @@  int loongarch_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
     if (0 <= n && n < 32) {
         return gdb_get_regl(mem_buf, env->gpr[n]);
     } else if (n == 32) {
-        return gdb_get_regl(mem_buf, env->pc);
+        /* orig_a0 */
+        return gdb_get_regl(mem_buf, env->gpr[4]);
     } else if (n == 33) {
+        return gdb_get_regl(mem_buf, env->pc);
+    } else if (n == 34) {
         return gdb_get_regl(mem_buf, env->CSR_BADV);
     }
     return 0;
@@ -36,7 +39,7 @@  int loongarch_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
     if (0 <= n && n < 32) {
         env->gpr[n] = tmp;
         length = sizeof(target_ulong);
-    } else if (n == 32) {
+    } else if (n == 33) {
         env->pc = tmp;
         length = sizeof(target_ulong);
     }