[v1] gdbstub: Always infer base register index from GDB XML

[PULL 12/16] gdbstub: Consider GDBFeature::base_reg in gdb_register_coprocessor()

Pierrick Bouvier posted 16 patches 4 weeks ago

Diff against v1 v2 v3 v4
Download mbox

Maintainers: Warner Losh <imp@bsdimp.com>, Kyle Evans <kevans@freebsd.org>, Laurent Vivier <laurent@vivier.eu>, Pierrick Bouvier <pierrick.bouvier@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Zhao Liu <zhao1.liu@intel.com>, Song Gao <gaosong@loongson.cn>, Bibo Mao <maobibo@loongson.cn>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Weiwei Li <liwei1518@gmail.com>, Daniel Henrique Barboza <dbarboza@ventanamicro.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>, Thomas Huth <thuth@redhat.com>, "Alex Bennée" <alex.bennee@linaro.org>, "Daniel P. Berrangé" <berrange@redhat.com>, Markus Armbruster <armbru@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, John Snow <jsnow@redhat.com>, Cleber Rosa <crosa@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Brian Cain <brian.cain@oss.qualcomm.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Nicholas Piggin <npiggin@gmail.com>, Chinmay Rath <rathc@linux.ibm.com>, Glenn Miles <milesg@linux.ibm.com>, Richard Henderson <richard.henderson@linaro.org>, Ilya Leoshkevich <iii@linux.ibm.com>, David Hildenbrand <david@kernel.org>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Artyom Tarasenko <atar4qemu@gmail.com>

There is a newer version of this series

Expand all Fold all

[PULL 12/16] gdbstub: Consider GDBFeature::base_reg in gdb_register_coprocessor()

Posted by Pierrick Bouvier 4 weeks ago

From: Philippe Mathieu-Daudé <philmd@linaro.org>

When a feature XML file provides a "regnum=" tag to indicate
the registers base index, respect it, as it might not be the
same as our current number of registered entries, in particular
when there are gaps.

This fixes a bug with the "power-fpu.xml" file [*] which was
loaded at index 70 while the base register is 71. This latent
bug was exposed by commit 1ec0fbe2dda ("target/ppc: Fix
CPUClass::gdb_num_core_regs value").

[*] https://lore.kernel.org/qemu-devel/e44df309-d40d-46f0-88a8-7ac55f9a3634@fhofhammer.de/

Reported-by: Florian Hofhammer <florian.hofhammer@fhofhammer.de>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Tested-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Link: https://lore.kernel.org/qemu-devel/20260310232045.58440-13-philmd@linaro.org
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
---
 gdbstub/gdbstub.c    | 6 ++++++
 gdbstub/trace-events | 1 +
 2 files changed, 7 insertions(+)

diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 69038c66f2b..c3c944e965b 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -601,6 +601,7 @@ void gdb_init_cpu(CPUState *cpu)
     if (xmlfile) {
         assert(!cc->gdb_num_core_regs);
         feature = gdb_find_static_feature(xmlfile);
+        assert(feature->base_reg == 0);
         gdb_register_feature(cpu, 0,
                              cc->gdb_read_register, cc->gdb_write_register,
                              feature);
@@ -630,6 +631,11 @@ void gdb_register_coprocessor(CPUState *cpu,
         }
     }
 
+    if (base_reg < feature->base_reg) {
+        trace_gdbxml_register_coprocessor_gap(base_reg,
+                                              feature->base_reg);
+        base_reg = feature->base_reg;
+    }
     gdb_register_feature(cpu, base_reg, get_reg, set_reg, feature);
 
     /* Add to end of list.  */
diff --git a/gdbstub/trace-events b/gdbstub/trace-events
index 8caee36c242..5bc83946743 100644
--- a/gdbstub/trace-events
+++ b/gdbstub/trace-events
@@ -29,6 +29,7 @@ gdbstub_err_checksum_incorrect(uint8_t expected, uint8_t got) "got command packe
 gdbstub_err_unexpected_runpkt(uint8_t ch) "unexpected packet (0x%02x) while target running"
 
 gdbxml_init_cpu(const char *typename, unsigned id, unsigned gdb_num_regs, unsigned gdb_num_g_regs, unsigned gdb_num_core_regs) "%s:%d regs:%u g_regs:%u core_regs:%u"
+gdbxml_register_coprocessor_gap(unsigned gdb_num_regs, unsigned base_reg) "regs %u -> %u"
 gdbxml_register_feature(const char *featname, const char *xmlname, unsigned base_reg, unsigned num_regs) "%s (%s) @%u +%u"
 gdbxml_feature_builder_header(const char *name, const char *xmlname, int num_regs) "%s (%s) regs:%d"
 gdbxml_feature_builder_content(const char *xml) "%s"
-- 
2.47.3