[PULL 16/22] gdbstub: expose api to find registers

Alex Bennée posted 22 patches 1 year, 11 months ago
Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, "Alex Bennée" <alex.bennee@linaro.org>, Alexandre Iooss <erdnaxe@crans.org>, Mahmoud Mandour <ma.mandourr@gmail.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Bin Meng <bin.meng@windriver.com>, Weiwei Li <liwei1518@gmail.com>, Daniel Henrique Barboza <dbarboza@ventanamicro.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Yanan Wang <wangyanan55@huawei.com>, John Snow <jsnow@redhat.com>, Cleber Rosa <crosa@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Michael Rolnik <mrolnik@gmail.com>, Brian Cain <bcain@quicinc.com>, Song Gao <gaosong@loongson.cn>, Laurent Vivier <laurent@vivier.eu>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Nicholas Piggin <npiggin@gmail.com>, "Cédric Le Goater" <clg@kaod.org>, Yoshinori Sato <ysato@users.sourceforge.jp>, David Hildenbrand <david@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Thomas Huth <thuth@redhat.com>
[PULL 16/22] gdbstub: expose api to find registers
Posted by Alex Bennée 1 year, 11 months ago
Expose an internal API to QEMU to return all the registers for a vCPU.
The list containing the details required to called gdb_read_register().

Based-on: <20231025093128.33116-15-akihiko.odaki@daynix.com>
Cc: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20240103173349.398526-38-alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index da9ddfe54c5..7bddea8259e 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -111,6 +111,53 @@ void gdb_feature_builder_end(const GDBFeatureBuilder *builder);
  */
 const GDBFeature *gdb_find_static_feature(const char *xmlname);
 
+/**
+ * gdb_find_feature() - Find a feature associated with a CPU.
+ * @cpu: The CPU associated with the feature.
+ * @name: The feature's name.
+ *
+ * Return: The feature's number.
+ */
+int gdb_find_feature(CPUState *cpu, const char *name);
+
+/**
+ * gdb_find_feature_register() - Find a register associated with a CPU.
+ * @cpu: The CPU associated with the register.
+ * @feature: The feature's number returned by gdb_find_feature().
+ * @name: The register's name.
+ *
+ * Return: The register's number.
+ */
+int gdb_find_feature_register(CPUState *cpu, int feature, const char *name);
+
+/**
+ * gdb_read_register() - Read a register associated with a CPU.
+ * @cpu: The CPU associated with the register.
+ * @buf: The buffer that the read register will be appended to.
+ * @reg: The register's number returned by gdb_find_feature_register().
+ *
+ * Return: The number of read bytes.
+ */
+int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
+
+/**
+ * typedef GDBRegDesc - a register description from gdbstub
+ */
+typedef struct {
+    int gdb_reg;
+    const char *name;
+    const char *feature_name;
+} GDBRegDesc;
+
+/**
+ * gdb_get_register_list() - Return list of all registers for CPU
+ * @cpu: The CPU being searched
+ *
+ * Returns a GArray of GDBRegDesc, caller frees array but not the
+ * const strings.
+ */
+GArray *gdb_get_register_list(CPUState *cpu);
+
 void gdb_set_stop_cpu(CPUState *cpu);
 
 /* in gdbstub-xml.c, generated by scripts/feature_to_c.py */
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 420ab2a3766..b0230138246 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -490,7 +490,61 @@ const GDBFeature *gdb_find_static_feature(const char *xmlname)
     g_assert_not_reached();
 }
 
-static int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
+int gdb_find_feature(CPUState *cpu, const char *name)
+{
+    GDBRegisterState *r;
+
+    for (guint i = 0; i < cpu->gdb_regs->len; i++) {
+        r = &g_array_index(cpu->gdb_regs, GDBRegisterState, i);
+        if (!strcmp(name, r->feature->name)) {
+            return i;
+        }
+    }
+
+    return -1;
+}
+
+int gdb_find_feature_register(CPUState *cpu, int feature, const char *name)
+{
+    GDBRegisterState *r;
+
+    r = &g_array_index(cpu->gdb_regs, GDBRegisterState, feature);
+
+    for (int i = 0; i < r->feature->num_regs; i++) {
+        if (r->feature->regs[i] && !strcmp(name, r->feature->regs[i])) {
+            return r->base_reg + i;
+        }
+    }
+
+    return -1;
+}
+
+GArray *gdb_get_register_list(CPUState *cpu)
+{
+    GArray *results = g_array_new(true, true, sizeof(GDBRegDesc));
+
+    /* registers are only available once the CPU is initialised */
+    if (!cpu->gdb_regs) {
+        return results;
+    }
+
+    for (int f = 0; f < cpu->gdb_regs->len; f++) {
+        GDBRegisterState *r = &g_array_index(cpu->gdb_regs, GDBRegisterState, f);
+        for (int i = 0; i < r->feature->num_regs; i++) {
+            const char *name = r->feature->regs[i];
+            GDBRegDesc desc = {
+                r->base_reg + i,
+                name,
+                r->feature->name
+            };
+            g_array_append_val(results, desc);
+        }
+    }
+
+    return results;
+}
+
+int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);
     GDBRegisterState *r;
-- 
2.39.2


Re: [PULL 16/22] gdbstub: expose api to find registers
Posted by Akihiko Odaki 1 year, 11 months ago
On 2024/01/16 19:48, Alex Bennée wrote:
> Expose an internal API to QEMU to return all the registers for a vCPU.
> The list containing the details required to called gdb_read_register().
> 
> Based-on: <20231025093128.33116-15-akihiko.odaki@daynix.com>
> Cc: Akihiko Odaki <akihiko.odaki@daynix.com>
> Message-Id: <20240103173349.398526-38-alex.bennee@linaro.org>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

I'm not for to pull this, "[PULL 17/22] plugins: add an API to read 
registers", and "[PULL 19/22] contrib/plugins: extend execlog to track 
register changes" in the current state. I have only commented the API 
aspect of these patches, but looking at them now, I see something wrong 
with their implementations. I'll add comments to respective patches.

> 
> diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
> index da9ddfe54c5..7bddea8259e 100644
> --- a/include/exec/gdbstub.h
> +++ b/include/exec/gdbstub.h
> @@ -111,6 +111,53 @@ void gdb_feature_builder_end(const GDBFeatureBuilder *builder);
>    */
>   const GDBFeature *gdb_find_static_feature(const char *xmlname);
>   
> +/**
> + * gdb_find_feature() - Find a feature associated with a CPU.
> + * @cpu: The CPU associated with the feature.
> + * @name: The feature's name.
> + *
> + * Return: The feature's number.
> + */
> +int gdb_find_feature(CPUState *cpu, const char *name);

This function is not used.

> +
> +/**
> + * gdb_find_feature_register() - Find a register associated with a CPU.
> + * @cpu: The CPU associated with the register.
> + * @feature: The feature's number returned by gdb_find_feature().
> + * @name: The register's name.
> + *
> + * Return: The register's number.
> + */
> +int gdb_find_feature_register(CPUState *cpu, int feature, const char *name);

This function is also no longer needed.

Regards,
Akihiko Odaki

Re: [PULL 16/22] gdbstub: expose api to find registers
Posted by Alex Bennée 1 year, 11 months ago
Akihiko Odaki <akihiko.odaki@daynix.com> writes:

> On 2024/01/16 19:48, Alex Bennée wrote:
>> Expose an internal API to QEMU to return all the registers for a vCPU.
>> The list containing the details required to called gdb_read_register().
>> Based-on: <20231025093128.33116-15-akihiko.odaki@daynix.com>
>> Cc: Akihiko Odaki <akihiko.odaki@daynix.com>
>> Message-Id: <20240103173349.398526-38-alex.bennee@linaro.org>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>
> I'm not for to pull this, "[PULL 17/22] plugins: add an API to read
> registers", and "[PULL 19/22] contrib/plugins: extend execlog to track
> register changes" in the current state. I have only commented the API
> aspect of these patches, but looking at them now, I see something
> wrong with their implementations. I'll add comments to respective
> patches.

OK - the patches where on the list for 14 days so I was going to merge
as is and fix up any issues after the fact. But if there is review
incoming I can re-spin without the final series.

There is other plugin activity going on I'd like to get merged this
cycle so I don't want to hold stuff up.

>
>> diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
>> index da9ddfe54c5..7bddea8259e 100644
>> --- a/include/exec/gdbstub.h
>> +++ b/include/exec/gdbstub.h
>> @@ -111,6 +111,53 @@ void gdb_feature_builder_end(const GDBFeatureBuilder *builder);
>>    */
>>   const GDBFeature *gdb_find_static_feature(const char *xmlname);
>>   +/**
>> + * gdb_find_feature() - Find a feature associated with a CPU.
>> + * @cpu: The CPU associated with the feature.
>> + * @name: The feature's name.
>> + *
>> + * Return: The feature's number.
>> + */
>> +int gdb_find_feature(CPUState *cpu, const char *name);
>
> This function is not used.
>
>> +
>> +/**
>> + * gdb_find_feature_register() - Find a register associated with a CPU.
>> + * @cpu: The CPU associated with the register.
>> + * @feature: The feature's number returned by gdb_find_feature().
>> + * @name: The register's name.
>> + *
>> + * Return: The register's number.
>> + */
>> +int gdb_find_feature_register(CPUState *cpu, int feature, const char *name);
>
> This function is also no longer needed.

Ahh looks like a merge failure when I re-based. 

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro