Re: [Qemu-devel] [PATCH v9 23/27] gdbstub: Implement qemu physical memory mode

[Alex Bennée]

Jon Doron <address@hidden> writes:

> Add a new query/set which changes the memory GDB sees to physical memory
> only.
>
> gdb> maint packet qqemu.PhyMemMode
> will reply the current phy_mem_mode state (1 for enabled, 0 for disabled)
> gdb> maint packet Qqemu.PhyMemMode:1
> Will make GDB read/write only to physical memory, set to 0 to disable
>
> Signed-off-by: Jon Doron <address@hidden>
> ---
>  gdbstub.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 55 insertions(+), 3 deletions(-)
>
> diff --git a/gdbstub.c b/gdbstub.c
> index 00c07d6ec0..88ff6224e6 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -46,11 +46,23 @@
>  #define GDB_ATTACHED "1"
>  #endif
>
> +static int phy_memory_mode;
> +
>  static inline int target_memory_rw_debug(CPUState *cpu, target_ulong addr,
>                                           uint8_t *buf, int len, bool 
> is_write)
>  {
> -    CPUClass *cc = CPU_GET_CLASS(cpu);
> +    CPUClass *cc;
>
> +    if (phy_memory_mode) {
> +        if (is_write) {
> +            cpu_physical_memory_write(addr, buf, len);
> +        } else {
> +            cpu_physical_memory_read(addr, buf, len);
> +        }
> +        return 0;
> +    }
> +

I think this is the commit that breaks the build. As the gdbstub can run
for both system and linux-user emulation modes you need to take care to
disable the bits that don't make sense for linux-user emulation. You'll
see other places in the code doing that with #if[n]def CONFIG_USER_ONLY.


> +    cc = CPU_GET_CLASS(cpu);
>      if (cc->memory_rw_debug) {
>          return cc->memory_rw_debug(cpu, addr, buf, len, is_write);
>      }
> @@ -2129,7 +2141,29 @@ static void handle_query_attached(GdbCmdContext 
> *gdb_ctx, void *user_ctx)
>
>  static void handle_query_qemu_supported(GdbCmdContext *gdb_ctx, void 
> *user_ctx)
>  {
> -    put_packet(gdb_ctx->s, "sstepbits;sstep");
> +    put_packet(gdb_ctx->s, "sstepbits;sstep;PhyMemMode");
> +}
> +
> +static void handle_query_qemu_phy_mem_mode(GdbCmdContext *gdb_ctx,
> +                                           void *user_ctx)
> +{
> +    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "%d", 
> phy_memory_mode);
> +    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
> +}
> +
> +static void handle_set_qemu_phy_mem_mode(GdbCmdContext *gdb_ctx, void 
> *user_ctx)
> +{
> +    if (!gdb_ctx->num_params) {
> +        put_packet(gdb_ctx->s, "E22");
> +        return;
> +    }
> +
> +    if (!gdb_ctx->params[0].val_ul) {
> +        phy_memory_mode = 0;
> +    } else {
> +        phy_memory_mode = 1;
> +    }
> +    put_packet(gdb_ctx->s, "OK");
>  }
>
>  static GdbCmdParseEntry gdb_gen_query_set_common_table[] = {
> @@ -2212,6 +2246,20 @@ static GdbCmdParseEntry gdb_gen_query_table[] = {
>          .handler = handle_query_qemu_supported,
>          .cmd = "qemu.Supported",
>      },
> +    {
> +        .handler = handle_query_qemu_phy_mem_mode,
> +        .cmd = "qemu.PhyMemMode",
> +    },
> +};
> +
> +static GdbCmdParseEntry gdb_gen_set_table[] = {
> +    /* Order is important if has same prefix */
> +    {
> +        .handler = handle_set_qemu_phy_mem_mode,
> +        .cmd = "qemu.PhyMemMode:",
> +        .cmd_startswith = 1,
> +        .schema = "l0"
> +    },
>  };
>
>  static void handle_gen_query(GdbCmdContext *gdb_ctx, void *user_ctx)
> @@ -2245,7 +2293,11 @@ static void handle_gen_set(GdbCmdContext *gdb_ctx, 
> void *user_ctx)
>          return;
>      }
>
> -    put_packet(gdb_ctx->s, "");
> +    if (process_string_cmd(gdb_ctx->s, NULL, gdb_ctx->params[0].data,
> +                           gdb_gen_set_table,
> +                           ARRAY_SIZE(gdb_gen_set_table))) {
> +        put_packet(gdb_ctx->s, "");
> +    }
>  }
>
>  static void handle_target_halt(GdbCmdContext *gdb_ctx, void *user_ctx)


--
Alex Bennée