| Message ID | 20240416040609.1313605-5-richard.henderson@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | plugins: Use unwind info for special gdb registers | expand |
On 4/15/24 21:06, Richard Henderson wrote: > Certain target registers are not updated continuously within > the translation block. For normal exception handling we use > unwind info to re-generate the correct value when required. > Leverage that same info for reading those registers for plugins. > > All targets will need updating for these new callbacks. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > include/hw/core/tcg-cpu-ops.h | 13 +++++++++++++ > plugins/api.c | 36 +++++++++++++++++++++++++++++++++-- > 2 files changed, 47 insertions(+), 2 deletions(-) > > diff --git a/include/hw/core/tcg-cpu-ops.h b/include/hw/core/tcg-cpu-ops.h > index bf8ff8e3ee..e954d83edf 100644 > --- a/include/hw/core/tcg-cpu-ops.h > +++ b/include/hw/core/tcg-cpu-ops.h > @@ -49,6 +49,19 @@ struct TCGCPUOps { > /** @debug_excp_handler: Callback for handling debug exceptions */ > void (*debug_excp_handler)(CPUState *cpu); > > + /** > + * @plugin_need_unwind_for_reg: > + * True if unwind info needed for reading reg. > + */ > + bool (*plugin_need_unwind_for_reg)(CPUState *cpu, int reg); > + /** > + * @plugin_unwind_read_reg: > + * Like CPUClass.gdb_read_register, but for registers that require > + * regeneration using unwind info, like in @restore_state_to_opc. > + */ > + int (*plugin_unwind_read_reg)(CPUState *cpu, GByteArray *buf, int reg, > + const TranslationBlock *tb, > + const uint64_t *data); > #ifdef NEED_CPU_H > #ifdef CONFIG_USER_ONLY > /** > diff --git a/plugins/api.c b/plugins/api.c > index 3912c9cc8f..3543647a89 100644 > --- a/plugins/api.c > +++ b/plugins/api.c > @@ -40,10 +40,12 @@ > #include "qemu/plugin.h" > #include "qemu/log.h" > #include "tcg/tcg.h" > +#include "tcg/insn-start-words.h" > #include "exec/exec-all.h" > #include "exec/gdbstub.h" > #include "exec/ram_addr.h" > #include "disas/disas.h" > +#include "hw/core/tcg-cpu-ops.h" > #include "plugin.h" > #ifndef CONFIG_USER_ONLY > #include "qemu/plugin-memory.h" > @@ -454,9 +456,39 @@ GArray *qemu_plugin_get_registers(void) > > int qemu_plugin_read_register(struct qemu_plugin_register *reg, GByteArray *buf) > { > - g_assert(current_cpu); > + CPUState *cs; > + uintptr_t ra; > + int regno; > > - return gdb_read_register(current_cpu, buf, GPOINTER_TO_INT(reg)); > + assert(current_cpu); > + cs = current_cpu; > + ra = cs->neg.plugin_ra; > + regno = GPOINTER_TO_INT(reg); > + > + /* > + * When plugin_ra is 0, we have no unwind info. This will be true for > + * TB callbacks that happen before any insns of the TB have started. > + */ > + if (ra) { > + const TCGCPUOps *tcg_ops = cs->cc->tcg_ops; > + > + /* > + * For plugins in the middle of the TB, we may need to locate > + * and use unwind data to reconstruct a register value. > + * Usually this required for the PC, but there may be others. > + */ > + if (tcg_ops->plugin_need_unwind_for_reg && > + tcg_ops->plugin_need_unwind_for_reg(cs, regno)) { > + uint64_t data[TARGET_INSN_START_WORDS]; > + const TranslationBlock *tb; > + > + tb = cpu_unwind_state_data(cs, ra, data); > + assert(tb); > + return tcg_ops->plugin_unwind_read_reg(cs, buf, regno, tb, data); > + } > + } > + > + return gdb_read_register(cs, buf, regno); > } > > struct qemu_plugin_scoreboard *qemu_plugin_scoreboard_new(size_t element_size) Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
diff --git a/include/hw/core/tcg-cpu-ops.h b/include/hw/core/tcg-cpu-ops.h index bf8ff8e3ee..e954d83edf 100644 --- a/include/hw/core/tcg-cpu-ops.h +++ b/include/hw/core/tcg-cpu-ops.h @@ -49,6 +49,19 @@ struct TCGCPUOps { /** @debug_excp_handler: Callback for handling debug exceptions */ void (*debug_excp_handler)(CPUState *cpu); + /** + * @plugin_need_unwind_for_reg: + * True if unwind info needed for reading reg. + */ + bool (*plugin_need_unwind_for_reg)(CPUState *cpu, int reg); + /** + * @plugin_unwind_read_reg: + * Like CPUClass.gdb_read_register, but for registers that require + * regeneration using unwind info, like in @restore_state_to_opc. + */ + int (*plugin_unwind_read_reg)(CPUState *cpu, GByteArray *buf, int reg, + const TranslationBlock *tb, + const uint64_t *data); #ifdef NEED_CPU_H #ifdef CONFIG_USER_ONLY /** diff --git a/plugins/api.c b/plugins/api.c index 3912c9cc8f..3543647a89 100644 --- a/plugins/api.c +++ b/plugins/api.c @@ -40,10 +40,12 @@ #include "qemu/plugin.h" #include "qemu/log.h" #include "tcg/tcg.h" +#include "tcg/insn-start-words.h" #include "exec/exec-all.h" #include "exec/gdbstub.h" #include "exec/ram_addr.h" #include "disas/disas.h" +#include "hw/core/tcg-cpu-ops.h" #include "plugin.h" #ifndef CONFIG_USER_ONLY #include "qemu/plugin-memory.h" @@ -454,9 +456,39 @@ GArray *qemu_plugin_get_registers(void) int qemu_plugin_read_register(struct qemu_plugin_register *reg, GByteArray *buf) { - g_assert(current_cpu); + CPUState *cs; + uintptr_t ra; + int regno; - return gdb_read_register(current_cpu, buf, GPOINTER_TO_INT(reg)); + assert(current_cpu); + cs = current_cpu; + ra = cs->neg.plugin_ra; + regno = GPOINTER_TO_INT(reg); + + /* + * When plugin_ra is 0, we have no unwind info. This will be true for + * TB callbacks that happen before any insns of the TB have started. + */ + if (ra) { + const TCGCPUOps *tcg_ops = cs->cc->tcg_ops; + + /* + * For plugins in the middle of the TB, we may need to locate + * and use unwind data to reconstruct a register value. + * Usually this required for the PC, but there may be others. + */ + if (tcg_ops->plugin_need_unwind_for_reg && + tcg_ops->plugin_need_unwind_for_reg(cs, regno)) { + uint64_t data[TARGET_INSN_START_WORDS]; + const TranslationBlock *tb; + + tb = cpu_unwind_state_data(cs, ra, data); + assert(tb); + return tcg_ops->plugin_unwind_read_reg(cs, buf, regno, tb, data); + } + } + + return gdb_read_register(cs, buf, regno); } struct qemu_plugin_scoreboard *qemu_plugin_scoreboard_new(size_t element_size)
Certain target registers are not updated continuously within the translation block. For normal exception handling we use unwind info to re-generate the correct value when required. Leverage that same info for reading those registers for plugins. All targets will need updating for these new callbacks. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- include/hw/core/tcg-cpu-ops.h | 13 +++++++++++++ plugins/api.c | 36 +++++++++++++++++++++++++++++++++-- 2 files changed, 47 insertions(+), 2 deletions(-)