Aaron Lindsay <aa...@os.amperecomputing.com> writes:
> On Feb 12 16:04, Alex Bennée wrote:
>> Do you see two stores or one store? I think I got the sense the wrong
>> way around because the store is instrumented before the mmu code,
>> hence should be skipped on a re-instrumented block.
>
> I only see one store between the instruction callback for the store and
> the instruction callback for the subsequent instruction.
I've posted:
Subject: [PATCH v3 00/23] plugins/next pre-PR (hwprofile, regression fixes,
icount count fix)
Date: Sat, 13 Feb 2021 13:03:02 +0000
Message-Id: <20210213130325.14781-1-alex.ben...@linaro.org>
which I think solves it. Could you have a look?
>
> -Aaron
>
>> On Fri, 12 Feb 2021 at 15:41, Aaron Lindsay
>> <aa...@os.amperecomputing.com> wrote:
>> >
>> > On Feb 12 14:43, Alex Bennée wrote:
>> > > Aaron Lindsay <aa...@os.amperecomputing.com> writes:
>> > > > On Feb 10 22:10, Alex Bennée wrote:
>> > > >> When icount is enabled and we recompile an MMIO access we end up
>> > > >> double counting the instruction execution. To avoid this we introduce
>> > > >> the CF_NOINSTR cflag which disables instrumentation for the next TB.
>> > > >> As this is part of the hashed compile flags we will only execute the
>> > > >> generated TB while coming out of a cpu_io_recompile.
>> > > >
>> > > > Unfortunately this patch works a little too well!
>> > > >
>> > > > With this change, the memory access callbacks registered via
>> > > > `qemu_plugin_register_vcpu_mem_cb()` are never called for the
>> > > > re-translated instruction making the IO access, since we've disabled
>> > > > all
>> > > > instrumentation.
>> > > >
>> > > > Is it possible to selectively disable only instruction callbacks using
>> > > > this mechanism, while still allowing others that would not yet have
>> > > > been
>> > > > called for the re-translated instruction?
>> > >
>> > > Can you try the following fugly patch on top of this series:
>> >
>> > This patch does allow me to successfully observe memory callbacks for
>> > stores in this case. It seems from looking at the patch that you
>> > intentionally only allowed memory callbacks for stores in this case, and
>> > I still don't see callbacks any for loads.
>> >
>> > -Aaron
>> >
>> > > --8<---------------cut here---------------start------------->8---
>> > > diff --git a/include/exec/plugin-gen.h b/include/exec/plugin-gen.h
>> > > index 4834a9e2f4..b1b72b5d90 100644
>> > > --- a/include/exec/plugin-gen.h
>> > > +++ b/include/exec/plugin-gen.h
>> > > @@ -19,7 +19,7 @@ struct DisasContextBase;
>> > >
>> > > #ifdef CONFIG_PLUGIN
>> > >
>> > > -bool plugin_gen_tb_start(CPUState *cpu, const TranslationBlock *tb);
>> > > +bool plugin_gen_tb_start(CPUState *cpu, const TranslationBlock *tb,
>> > > bool supress);
>> > > void plugin_gen_tb_end(CPUState *cpu);
>> > > void plugin_gen_insn_start(CPUState *cpu, const struct DisasContextBase
>> > > *db);
>> > > void plugin_gen_insn_end(void);
>> > > @@ -41,7 +41,7 @@ static inline void plugin_insn_append(const void
>> > > *from, size_t size)
>> > > #else /* !CONFIG_PLUGIN */
>> > >
>> > > static inline
>> > > -bool plugin_gen_tb_start(CPUState *cpu, const TranslationBlock *tb)
>> > > +bool plugin_gen_tb_start(CPUState *cpu, const TranslationBlock *tb,
>> > > bool supress)
>> > > {
>> > > return false;
>> > > }
>> > > diff --git a/include/qemu/plugin.h b/include/qemu/plugin.h
>> > > index 841deed79c..2a26a2277f 100644
>> > > --- a/include/qemu/plugin.h
>> > > +++ b/include/qemu/plugin.h
>> > > @@ -92,6 +92,7 @@ struct qemu_plugin_dyn_cb {
>> > > };
>> > > };
>> > >
>> > > +/* Internal context for instrumenting an instruction */
>> > > struct qemu_plugin_insn {
>> > > GByteArray *data;
>> > > uint64_t vaddr;
>> > > @@ -99,6 +100,7 @@ struct qemu_plugin_insn {
>> > > GArray *cbs[PLUGIN_N_CB_TYPES][PLUGIN_N_CB_SUBTYPES];
>> > > bool calls_helpers;
>> > > bool mem_helper;
>> > > + bool store_only;
>> > > };
>> > >
>> > > /*
>> > > @@ -128,6 +130,7 @@ static inline struct qemu_plugin_insn
>> > > *qemu_plugin_insn_alloc(void)
>> > > return insn;
>> > > }
>> > >
>> > > +/* Internal context for this TranslationBlock */
>> > > struct qemu_plugin_tb {
>> > > GPtrArray *insns;
>> > > size_t n;
>> > > @@ -135,6 +138,7 @@ struct qemu_plugin_tb {
>> > > uint64_t vaddr2;
>> > > void *haddr1;
>> > > void *haddr2;
>> > > + bool store_only;
>> > > GArray *cbs[PLUGIN_N_CB_SUBTYPES];
>> > > };
>> > >
>> > > diff --git a/accel/tcg/plugin-gen.c b/accel/tcg/plugin-gen.c
>> > > index 8a1bb801e0..137b91282e 100644
>> > > --- a/accel/tcg/plugin-gen.c
>> > > +++ b/accel/tcg/plugin-gen.c
>> > > @@ -842,7 +842,7 @@ static void plugin_gen_inject(const struct
>> > > qemu_plugin_tb *plugin_tb)
>> > > pr_ops();
>> > > }
>> > >
>> > > -bool plugin_gen_tb_start(CPUState *cpu, const TranslationBlock *tb)
>> > > +bool plugin_gen_tb_start(CPUState *cpu, const TranslationBlock *tb,
>> > > bool store_only)
>> > > {
>> > > struct qemu_plugin_tb *ptb = tcg_ctx->plugin_tb;
>> > > bool ret = false;
>> > > @@ -855,6 +855,7 @@ bool plugin_gen_tb_start(CPUState *cpu, const
>> > > TranslationBlock *tb)
>> > > ptb->vaddr2 = -1;
>> > > get_page_addr_code_hostp(cpu->env_ptr, tb->pc, &ptb->haddr1);
>> > > ptb->haddr2 = NULL;
>> > > + ptb->store_only = store_only;
>> > >
>> > > plugin_gen_empty_callback(PLUGIN_GEN_FROM_TB);
>> > > }
>> > > diff --git a/accel/tcg/translator.c b/accel/tcg/translator.c
>> > > index 14d1ea795d..082f2c8ee1 100644
>> > > --- a/accel/tcg/translator.c
>> > > +++ b/accel/tcg/translator.c
>> > > @@ -58,7 +58,7 @@ void translator_loop(const TranslatorOps *ops,
>> > > DisasContextBase *db,
>> > > ops->tb_start(db, cpu);
>> > > tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */
>> > >
>> > > - plugin_enabled = !(tb_cflags(db->tb) & CF_NOINSTR) &&
>> > > plugin_gen_tb_start(cpu, tb);
>> > > + plugin_enabled = plugin_gen_tb_start(cpu, tb, tb_cflags(db->tb) &
>> > > CF_NOINSTR);
>> > >
>> > > while (true) {
>> > > db->num_insns++;
>> > > @@ -100,6 +100,8 @@ void translator_loop(const TranslatorOps *ops,
>> > > DisasContextBase *db,
>> > > gen_io_start();
>> > > ops->translate_insn(db, cpu);
>> > > } else {
>> > > + /* we should only see NOINSTR for io_recompile */
>> > > + g_assert(!(tb_cflags(db->tb) & CF_NOINSTR));
>> > > ops->translate_insn(db, cpu);
>> > > }
>> > >
>> > > diff --git a/plugins/api.c b/plugins/api.c
>> > > index 5dc8e6f934..ac8475707d 100644
>> > > --- a/plugins/api.c
>> > > +++ b/plugins/api.c
>> > > @@ -84,15 +84,19 @@ void qemu_plugin_register_vcpu_tb_exec_cb(struct
>> > > qemu_plugin_tb *tb,
>> > > enum qemu_plugin_cb_flags
>> > > flags,
>> > > void *udata)
>> > > {
>> > > - plugin_register_dyn_cb__udata(&tb->cbs[PLUGIN_CB_REGULAR],
>> > > - cb, flags, udata);
>> > > + if (!tb->store_only) {
>> > > + plugin_register_dyn_cb__udata(&tb->cbs[PLUGIN_CB_REGULAR],
>> > > + cb, flags, udata);
>> > > + }
>> > > }
>> > >
>> > > void qemu_plugin_register_vcpu_tb_exec_inline(struct qemu_plugin_tb *tb,
>> > > enum qemu_plugin_op op,
>> > > void *ptr, uint64_t imm)
>> > > {
>> > > - plugin_register_inline_op(&tb->cbs[PLUGIN_CB_INLINE], 0, op, ptr,
>> > > imm);
>> > > + if (!tb->store_only) {
>> > > + plugin_register_inline_op(&tb->cbs[PLUGIN_CB_INLINE], 0, op,
>> > > ptr, imm);
>> > > + }
>> > > }
>> > >
>> > > void qemu_plugin_register_vcpu_insn_exec_cb(struct qemu_plugin_insn
>> > > *insn,
>> > > @@ -100,16 +104,20 @@ void qemu_plugin_register_vcpu_insn_exec_cb(struct
>> > > qemu_plugin_insn *insn,
>> > > enum qemu_plugin_cb_flags
>> > > flags,
>> > > void *udata)
>> > > {
>> > > -
>> > > plugin_register_dyn_cb__udata(&insn->cbs[PLUGIN_CB_INSN][PLUGIN_CB_REGULAR],
>> > > - cb, flags, udata);
>> > > + if (!insn->store_only) {
>> > > +
>> > > plugin_register_dyn_cb__udata(&insn->cbs[PLUGIN_CB_INSN][PLUGIN_CB_REGULAR],
>> > > + cb, flags, udata);
>> > > + }
>> > > }
>> > >
>> > > void qemu_plugin_register_vcpu_insn_exec_inline(struct qemu_plugin_insn
>> > > *insn,
>> > > enum qemu_plugin_op op,
>> > > void *ptr, uint64_t imm)
>> > > {
>> > > -
>> > > plugin_register_inline_op(&insn->cbs[PLUGIN_CB_INSN][PLUGIN_CB_INLINE],
>> > > - 0, op, ptr, imm);
>> > > + if (!insn->store_only) {
>> > > +
>> > > plugin_register_inline_op(&insn->cbs[PLUGIN_CB_INSN][PLUGIN_CB_INLINE],
>> > > + 0, op, ptr, imm);
>> > > + }
>> > > }
>> > >
>> > >
>> > > @@ -120,8 +128,13 @@ void qemu_plugin_register_vcpu_mem_cb(struct
>> > > qemu_plugin_insn *insn,
>> > > enum qemu_plugin_mem_rw rw,
>> > > void *udata)
>> > > {
>> > > -
>> > > plugin_register_vcpu_mem_cb(&insn->cbs[PLUGIN_CB_MEM][PLUGIN_CB_REGULAR],
>> > > - cb, flags, rw, udata);
>> > > + if (insn->store_only && (rw & QEMU_PLUGIN_MEM_W)) {
>> > > +
>> > > plugin_register_vcpu_mem_cb(&insn->cbs[PLUGIN_CB_MEM][PLUGIN_CB_REGULAR],
>> > > + cb, flags, QEMU_PLUGIN_MEM_W,
>> > > udata);
>> > > + } else {
>> > > +
>> > > plugin_register_vcpu_mem_cb(&insn->cbs[PLUGIN_CB_MEM][PLUGIN_CB_REGULAR],
>> > > + cb, flags, rw, udata);
>> > > + }
>> > > }
>> > >
>> > > void qemu_plugin_register_vcpu_mem_inline(struct qemu_plugin_insn *insn,
>> > > @@ -129,8 +142,10 @@ void qemu_plugin_register_vcpu_mem_inline(struct
>> > > qemu_plugin_insn *insn,
>> > > enum qemu_plugin_op op, void
>> > > *ptr,
>> > > uint64_t imm)
>> > > {
>> > > -
>> > > plugin_register_inline_op(&insn->cbs[PLUGIN_CB_MEM][PLUGIN_CB_INLINE],
>> > > - rw, op, ptr, imm);
>> > > + if (!insn->store_only) {
>> > > +
>> > > plugin_register_inline_op(&insn->cbs[PLUGIN_CB_MEM][PLUGIN_CB_INLINE],
>> > > + rw, op, ptr, imm);
>> > > + }
>> > > }
>> > >
>> > > void qemu_plugin_register_vcpu_tb_trans_cb(qemu_plugin_id_t id,
>> > > @@ -181,10 +196,13 @@ uint64_t qemu_plugin_tb_vaddr(const struct
>> > > qemu_plugin_tb *tb)
>> > > struct qemu_plugin_insn *
>> > > qemu_plugin_tb_get_insn(const struct qemu_plugin_tb *tb, size_t idx)
>> > > {
>> > > + struct qemu_plugin_insn *insn;
>> > > if (unlikely(idx >= tb->n)) {
>> > > return NULL;
>> > > }
>> > > - return g_ptr_array_index(tb->insns, idx);
>> > > + insn = g_ptr_array_index(tb->insns, idx);
>> > > + insn->store_only = tb->store_only;
>> > > + return insn;
>> > > }
>> > >
>> > > /*
>> > > --8<---------------cut here---------------end--------------->8---
>> > >
>> > > --
>> > > Alex Bennée
>>
>>
>>
>> --
>> Alex Bennée
>> KVM/QEMU Hacker for Linaro
--
Alex Bennée
