gdbstub: Clarify no more than @gdb_num_core_regs can be accessed

Both CPUClass::gdb_read_register() and CPUClass::gdb_write_register()
handlers are called from common gdbstub code, and won't be called with
register index over CPUClass::gdb_num_core_regs:

  int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
  {
      CPUClass *cc = CPU_GET_CLASS(cpu);

      if (reg < cc->gdb_num_core_regs) {
          return cc->gdb_read_register(cpu, buf, reg);
      }
      ...
  }

  static int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
  {
      CPUClass *cc = CPU_GET_CLASS(cpu);

      if (reg < cc->gdb_num_core_regs) {
          return cc->gdb_write_register(cpu, mem_buf, reg);
      }
      ...
  }

Clarify that in CPUClass docstring, and remove unreachable code on
the microblaze and openrisc implementations.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250122093028.52416-3-philmd@linaro.org>

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index fb397cdfc53d12d40d3e4e7f86251fc31c48b9f6..7b6b22c431b7263e504578884bb8d52281fe02b8 100644 (file)
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -124,7 +124,9 @@ struct SysemuCPUOps;
  * @get_pc: Callback for getting the Program Counter register.
  *       As above, with the semantics of the target architecture.
  * @gdb_read_register: Callback for letting GDB read a register.
+ *                     No more than @gdb_num_core_regs registers can be read.
  * @gdb_write_register: Callback for letting GDB write a register.
+ *                     No more than @gdb_num_core_regs registers can be written.
  * @gdb_adjust_breakpoint: Callback for adjusting the address of a
  *       breakpoint.  Used by AVR to handle a gdb mis-feature with
  *       its Harvard architecture split code and data.

diff --git a/target/microblaze/gdbstub.c b/target/microblaze/gdbstub.c
index 09d74e164d0d4f64340b71b64b3a987631b5396d..d493681d38d36d5c3bef219d782b7b22a66661f3 100644 (file)
--- a/target/microblaze/gdbstub.c
+++ b/target/microblaze/gdbstub.c
@@ -110,14 +110,9 @@ int mb_cpu_gdb_read_stack_protect(CPUState *cs, GByteArray *mem_buf, int n)
 
 int mb_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
 {
-    CPUClass *cc = CPU_GET_CLASS(cs);
     CPUMBState *env = cpu_env(cs);
     uint32_t tmp;
 
-    if (n > cc->gdb_num_core_regs) {
-        return 0;
-    }
-
     tmp = ldl_p(mem_buf);
 
     switch (n) {

diff --git a/target/openrisc/gdbstub.c b/target/openrisc/gdbstub.c
index c2a77d5d4d5214145d2b535d2b293e0f7447a209..45bba80d8789d7297d8e5d2cafcbc60407f2f486 100644 (file)
--- a/target/openrisc/gdbstub.c
+++ b/target/openrisc/gdbstub.c
@@ -47,14 +47,9 @@ int openrisc_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 
 int openrisc_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
 {
-    CPUClass *cc = CPU_GET_CLASS(cs);
     CPUOpenRISCState *env = cpu_env(cs);
     uint32_t tmp;
 
-    if (n > cc->gdb_num_core_regs) {
-        return 0;
-    }
-
     tmp = ldl_p(mem_buf);
 
     if (n < 32) {