| Message ID | 20201214140314.18544-8-richard.henderson@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Mirror map JIT memory for TCG | expand |
On 12/14/20 3:02 PM, Richard Henderson wrote: > Create a function to determine if a pointer is within the buffer. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > include/tcg/tcg.h | 6 ++++++ > accel/tcg/translate-all.c | 26 ++++++++------------------ > 2 files changed, 14 insertions(+), 18 deletions(-) > > diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h > index bb1e97b13b..e4d0ace44b 100644 > --- a/include/tcg/tcg.h > +++ b/include/tcg/tcg.h > @@ -680,6 +680,12 @@ extern __thread TCGContext *tcg_ctx; > extern void *tcg_code_gen_epilogue; > extern TCGv_env cpu_env; > > +static inline bool in_code_gen_buffer(const void *p) > +{ > + const TCGContext *s = &tcg_init_ctx; > + return (size_t)(p - s->code_gen_buffer) <= s->code_gen_buffer_size; If 'p == s->code_gen_buffer + s->code_gen_buffer_size', is it really "in" the buffer? > +} > + > static inline size_t temp_idx(TCGTemp *ts) > { > ptrdiff_t n = ts - tcg_ctx->temps; > diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c > index 4572b4901f..744f97a717 100644 > --- a/accel/tcg/translate-all.c > +++ b/accel/tcg/translate-all.c > @@ -392,27 +392,18 @@ void tb_destroy(TranslationBlock *tb) > > bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) > { > - TranslationBlock *tb; > - bool r = false; > - uintptr_t check_offset; > - > - /* The host_pc has to be in the region of current code buffer. If > - * it is not we will not be able to resolve it here. The two cases > - * where host_pc will not be correct are: > + /* > + * The host_pc has to be in the region of the code buffer. > + * If it is not we will not be able to resolve it here. > + * The two cases where host_pc will not be correct are: > * > * - fault during translation (instruction fetch) > * - fault from helper (not using GETPC() macro) > * > * Either way we need return early as we can't resolve it here. > - * > - * We are using unsigned arithmetic so if host_pc < > - * tcg_init_ctx.code_gen_buffer check_offset will wrap to way > - * above the code_gen_buffer_size > */ > - check_offset = host_pc - (uintptr_t) tcg_init_ctx.code_gen_buffer; > - > - if (check_offset < tcg_init_ctx.code_gen_buffer_size) { > - tb = tcg_tb_lookup(host_pc); > + if (in_code_gen_buffer((const void *)host_pc)) { > + TranslationBlock *tb = tcg_tb_lookup(host_pc); > if (tb) { > cpu_restore_state_from_tb(cpu, tb, host_pc, will_exit); > if (tb_cflags(tb) & CF_NOCACHE) { > @@ -421,11 +412,10 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) > tcg_tb_remove(tb); > tb_destroy(tb); > } > - r = true; > + return true; > } > } > - > - return r; > + return false; > } > > static void page_init(void) >
On 12/14/20 4:09 PM, Philippe Mathieu-Daudé wrote: > On 12/14/20 3:02 PM, Richard Henderson wrote: >> Create a function to determine if a pointer is within the buffer. >> >> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> >> --- >> include/tcg/tcg.h | 6 ++++++ >> accel/tcg/translate-all.c | 26 ++++++++------------------ >> 2 files changed, 14 insertions(+), 18 deletions(-) >> >> diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h >> index bb1e97b13b..e4d0ace44b 100644 >> --- a/include/tcg/tcg.h >> +++ b/include/tcg/tcg.h >> @@ -680,6 +680,12 @@ extern __thread TCGContext *tcg_ctx; >> extern void *tcg_code_gen_epilogue; >> extern TCGv_env cpu_env; >> >> +static inline bool in_code_gen_buffer(const void *p) >> +{ >> + const TCGContext *s = &tcg_init_ctx; >> + return (size_t)(p - s->code_gen_buffer) <= s->code_gen_buffer_size; > > If 'p == s->code_gen_buffer + s->code_gen_buffer_size', > is it really "in" the buffer? Well, sort of. Compare the fact that in C, a pointer to the end of an array is valid as a pointer even though it can't be dereferenced. This is a pointer to the end of the buffer. Extra commentary required? r~
On 12/15/20 11:43 PM, Richard Henderson wrote: > On 12/14/20 4:09 PM, Philippe Mathieu-Daudé wrote: >> On 12/14/20 3:02 PM, Richard Henderson wrote: >>> Create a function to determine if a pointer is within the buffer. >>> >>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> >>> --- >>> include/tcg/tcg.h | 6 ++++++ >>> accel/tcg/translate-all.c | 26 ++++++++------------------ >>> 2 files changed, 14 insertions(+), 18 deletions(-) >>> >>> diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h >>> index bb1e97b13b..e4d0ace44b 100644 >>> --- a/include/tcg/tcg.h >>> +++ b/include/tcg/tcg.h >>> @@ -680,6 +680,12 @@ extern __thread TCGContext *tcg_ctx; >>> extern void *tcg_code_gen_epilogue; >>> extern TCGv_env cpu_env; >>> >>> +static inline bool in_code_gen_buffer(const void *p) >>> +{ >>> + const TCGContext *s = &tcg_init_ctx; >>> + return (size_t)(p - s->code_gen_buffer) <= s->code_gen_buffer_size; >> >> If 'p == s->code_gen_buffer + s->code_gen_buffer_size', >> is it really "in" the buffer? > > Well, sort of. > > Compare the fact that in C, a pointer to the end of an array is valid as a > pointer even though it can't be dereferenced. This is a pointer to the end of > the buffer. > > Extra commentary required? Preferably, since you change from '<' to '<=', this would make it clearer, then no question asked :) With it: Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Thanks, Phil.
diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h index bb1e97b13b..e4d0ace44b 100644 --- a/include/tcg/tcg.h +++ b/include/tcg/tcg.h @@ -680,6 +680,12 @@ extern __thread TCGContext *tcg_ctx; extern void *tcg_code_gen_epilogue; extern TCGv_env cpu_env; +static inline bool in_code_gen_buffer(const void *p) +{ + const TCGContext *s = &tcg_init_ctx; + return (size_t)(p - s->code_gen_buffer) <= s->code_gen_buffer_size; +} + static inline size_t temp_idx(TCGTemp *ts) { ptrdiff_t n = ts - tcg_ctx->temps; diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index 4572b4901f..744f97a717 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -392,27 +392,18 @@ void tb_destroy(TranslationBlock *tb) bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) { - TranslationBlock *tb; - bool r = false; - uintptr_t check_offset; - - /* The host_pc has to be in the region of current code buffer. If - * it is not we will not be able to resolve it here. The two cases - * where host_pc will not be correct are: + /* + * The host_pc has to be in the region of the code buffer. + * If it is not we will not be able to resolve it here. + * The two cases where host_pc will not be correct are: * * - fault during translation (instruction fetch) * - fault from helper (not using GETPC() macro) * * Either way we need return early as we can't resolve it here. - * - * We are using unsigned arithmetic so if host_pc < - * tcg_init_ctx.code_gen_buffer check_offset will wrap to way - * above the code_gen_buffer_size */ - check_offset = host_pc - (uintptr_t) tcg_init_ctx.code_gen_buffer; - - if (check_offset < tcg_init_ctx.code_gen_buffer_size) { - tb = tcg_tb_lookup(host_pc); + if (in_code_gen_buffer((const void *)host_pc)) { + TranslationBlock *tb = tcg_tb_lookup(host_pc); if (tb) { cpu_restore_state_from_tb(cpu, tb, host_pc, will_exit); if (tb_cflags(tb) & CF_NOCACHE) { @@ -421,11 +412,10 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) tcg_tb_remove(tb); tb_destroy(tb); } - r = true; + return true; } } - - return r; + return false; } static void page_init(void)
Create a function to determine if a pointer is within the buffer. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- include/tcg/tcg.h | 6 ++++++ accel/tcg/translate-all.c | 26 ++++++++------------------ 2 files changed, 14 insertions(+), 18 deletions(-) -- 2.25.1