| Message ID | 1502280338-23002-13-git-send-email-Dave.Martin@arm.com |
|---|---|
| State | New |
| Headers | show |
Dave Martin <Dave.Martin@arm.com> writes: > It's desirable to be able to reset the vector length to some sane > default for new processes, since the new binary and its libraries > processes may or may not be SVE-aware. > > This patch tracks the desired post-exec vector length (if any) in a > new thread member sve_vl_onexec, and adds a new thread flag > TIF_SVE_VL_INHERIT to control whether to inherit or reset the > vector length. Currently these are inactive. Subsequent patches > will provide the capability to configure them. > > Signed-off-by: Dave Martin <Dave.Martin@arm.com> > --- > arch/arm64/include/asm/processor.h | 1 + > arch/arm64/include/asm/thread_info.h | 1 + > arch/arm64/kernel/fpsimd.c | 13 +++++++++++++ > 3 files changed, 15 insertions(+) > > diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h > index 969feed..da8802a 100644 > --- a/arch/arm64/include/asm/processor.h > +++ b/arch/arm64/include/asm/processor.h > @@ -87,6 +87,7 @@ struct thread_struct { > struct fpsimd_state fpsimd_state; > void *sve_state; /* SVE registers, if any */ > u16 sve_vl; /* SVE vector length */ > + u16 sve_vl_onexec; /* SVE vl after next > exec */ Inconsistent size usage here as well... > unsigned long fault_address; /* fault info */ > unsigned long fault_code; /* ESR_EL1 value */ > struct debug_info debug; /* debugging */ > diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h > index 1a4b30b..bf9c552 100644 > --- a/arch/arm64/include/asm/thread_info.h > +++ b/arch/arm64/include/asm/thread_info.h > @@ -97,6 +97,7 @@ struct thread_info { > #define TIF_SINGLESTEP 21 > #define TIF_32BIT 22 /* 32bit process */ > #define TIF_SVE 23 /* Scalable Vector Extension in use */ > +#define TIF_SVE_VL_INHERIT 24 /* Inherit sve_vl_onexec across exec */ > > #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) > #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) > diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c > index 37dd1b2..80ecb2d 100644 > --- a/arch/arm64/kernel/fpsimd.c > +++ b/arch/arm64/kernel/fpsimd.c > @@ -108,6 +108,9 @@ static void task_fpsimd_save(void); > */ > static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state); > > +/* Default VL for tasks that don't set it explicitly: */ > +static int sve_default_vl = -1; > + > static void sve_free(struct task_struct *task) > { > kfree(task->thread.sve_state); > @@ -392,6 +395,9 @@ void fpsimd_flush_thread(void) > clear_thread_flag(TIF_SVE); > sve_free(current); > > + current->thread.sve_vl = current->thread.sve_vl_onexec ? > + current->thread.sve_vl_onexec : sve_default_vl; > + > /* > * User tasks must have a valid vector length set, but tasks > * forked early (e.g., init) may not initially have one. > @@ -401,6 +407,13 @@ void fpsimd_flush_thread(void) > * If not, something went badly wrong. > */ > BUG_ON(!sve_vl_valid(current->thread.sve_vl)); > + > + /* > + * If the task is not set to inherit, ensure that the vector > + * length will be reset by a subsequent exec: > + */ > + if (!test_thread_flag(TIF_SVE_VL_INHERIT)) > + current->thread.sve_vl_onexec = 0; > } > > set_thread_flag(TIF_FOREIGN_FPSTATE); -- Alex Bennée
On Tue, Aug 22, 2017 at 05:22:11PM +0100, Alex Bennée wrote: > > Dave Martin <Dave.Martin@arm.com> writes: > > > It's desirable to be able to reset the vector length to some sane > > default for new processes, since the new binary and its libraries > > processes may or may not be SVE-aware. > > > > This patch tracks the desired post-exec vector length (if any) in a > > new thread member sve_vl_onexec, and adds a new thread flag > > TIF_SVE_VL_INHERIT to control whether to inherit or reset the > > vector length. Currently these are inactive. Subsequent patches > > will provide the capability to configure them. > > > > Signed-off-by: Dave Martin <Dave.Martin@arm.com> > > --- > > arch/arm64/include/asm/processor.h | 1 + > > arch/arm64/include/asm/thread_info.h | 1 + > > arch/arm64/kernel/fpsimd.c | 13 +++++++++++++ > > 3 files changed, 15 insertions(+) > > > > diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h > > index 969feed..da8802a 100644 > > --- a/arch/arm64/include/asm/processor.h > > +++ b/arch/arm64/include/asm/processor.h > > @@ -87,6 +87,7 @@ struct thread_struct { > > struct fpsimd_state fpsimd_state; > > void *sve_state; /* SVE registers, if any */ > > u16 sve_vl; /* SVE vector length */ > > + u16 sve_vl_onexec; /* SVE vl after next > > exec */ > > Inconsistent size usage here as well... Agreed, the same history applies as for sve_vl. I'll replace this with an unsigned int. [...] Cheers ---Dave
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 969feed..da8802a 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -87,6 +87,7 @@ struct thread_struct { struct fpsimd_state fpsimd_state; void *sve_state; /* SVE registers, if any */ u16 sve_vl; /* SVE vector length */ + u16 sve_vl_onexec; /* SVE vl after next exec */ unsigned long fault_address; /* fault info */ unsigned long fault_code; /* ESR_EL1 value */ struct debug_info debug; /* debugging */ diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 1a4b30b..bf9c552 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -97,6 +97,7 @@ struct thread_info { #define TIF_SINGLESTEP 21 #define TIF_32BIT 22 /* 32bit process */ #define TIF_SVE 23 /* Scalable Vector Extension in use */ +#define TIF_SVE_VL_INHERIT 24 /* Inherit sve_vl_onexec across exec */ #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 37dd1b2..80ecb2d 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -108,6 +108,9 @@ static void task_fpsimd_save(void); */ static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state); +/* Default VL for tasks that don't set it explicitly: */ +static int sve_default_vl = -1; + static void sve_free(struct task_struct *task) { kfree(task->thread.sve_state); @@ -392,6 +395,9 @@ void fpsimd_flush_thread(void) clear_thread_flag(TIF_SVE); sve_free(current); + current->thread.sve_vl = current->thread.sve_vl_onexec ? + current->thread.sve_vl_onexec : sve_default_vl; + /* * User tasks must have a valid vector length set, but tasks * forked early (e.g., init) may not initially have one. @@ -401,6 +407,13 @@ void fpsimd_flush_thread(void) * If not, something went badly wrong. */ BUG_ON(!sve_vl_valid(current->thread.sve_vl)); + + /* + * If the task is not set to inherit, ensure that the vector + * length will be reset by a subsequent exec: + */ + if (!test_thread_flag(TIF_SVE_VL_INHERIT)) + current->thread.sve_vl_onexec = 0; } set_thread_flag(TIF_FOREIGN_FPSTATE);
It's desirable to be able to reset the vector length to some sane default for new processes, since the new binary and its libraries processes may or may not be SVE-aware. This patch tracks the desired post-exec vector length (if any) in a new thread member sve_vl_onexec, and adds a new thread flag TIF_SVE_VL_INHERIT to control whether to inherit or reset the vector length. Currently these are inactive. Subsequent patches will provide the capability to configure them. Signed-off-by: Dave Martin <Dave.Martin@arm.com> --- arch/arm64/include/asm/processor.h | 1 + arch/arm64/include/asm/thread_info.h | 1 + arch/arm64/kernel/fpsimd.c | 13 +++++++++++++ 3 files changed, 15 insertions(+)