From b3e88abb200c357235ae1de34cd17b0b1fb24d78 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Wed, 11 Mar 2026 00:20:40 +0100 Subject: [PATCH] gdbstub: Consider GDBFeature::base_reg in gdb_register_coprocessor() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Philippe Mathieu-Daudé Reviewed-by: Pierrick Bouvier Tested-by: Pierrick Bouvier Link: https://lore.kernel.org/qemu-devel/20260310232045.58440-13-philmd@linaro.org Signed-off-by: Pierrick Bouvier --- gdbstub/gdbstub.c | 6 ++++++ gdbstub/trace-events | 1 + 2 files changed, 7 insertions(+) diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c index 69038c66f2..c3c944e965 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 8caee36c24..5bc8394674 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"