| Message ID | 1413467525-30304-4-git-send-email-yogesh.tillu@linaro.org |
|---|---|
| State | New |
| Headers | show |
If the cycle counter is enabled from user space, the kernel won't know that it is enabled for this thread. What happens if the thread is migrated to another core? I guess that the user space cycle counter access is not part of the process/thread context so not migrated with the thread. -- Ola On 16 October 2014 15:52, Yogesh Tillu <yogesh.tillu@linaro.org> wrote: > Signed-off-by: Yogesh Tillu <yogesh.tillu@linaro.org> > --- > arch/arm64/kernel/vdso/Makefile | 6 +++--- > arch/arm64/kernel/vdso/vdso.lds.S | 5 +++++ > arch/arm64/kernel/vdso/vdso_perfc.c | 20 ++++++++++++++++++++ > 3 files changed, 28 insertions(+), 3 deletions(-) > create mode 100644 arch/arm64/kernel/vdso/vdso_perfc.c > > diff --git a/arch/arm64/kernel/vdso/Makefile > b/arch/arm64/kernel/vdso/Makefile > index 6d20b7d..4fde490 100644 > --- a/arch/arm64/kernel/vdso/Makefile > +++ b/arch/arm64/kernel/vdso/Makefile > @@ -5,7 +5,7 @@ > # Heavily based on the vDSO Makefiles for other archs. > # > > -obj-vdso := gettimeofday.o note.o sigreturn.o > +obj-vdso := gettimeofday.o note.o sigreturn.o armpmu.o > > # Build rules > targets := $(obj-vdso) vdso.so vdso.so.dbg > @@ -43,8 +43,8 @@ $(obj)/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE > $(call if_changed,vdsosym) > > # Assembly rules for the .S files > -$(obj-vdso): %.o: %.S > - $(call if_changed_dep,vdsoas) > +#$(obj-vdso): %.o: %.S > +# $(call if_changed_dep,vdsoas) > > # Actual build commands > quiet_cmd_vdsold = VDSOL $@ > diff --git a/arch/arm64/kernel/vdso/vdso.lds.S > b/arch/arm64/kernel/vdso/vdso.lds.S > index 8154b8d..8cb56e0 100644 > --- a/arch/arm64/kernel/vdso/vdso.lds.S > +++ b/arch/arm64/kernel/vdso/vdso.lds.S > @@ -90,6 +90,11 @@ VERSION > __kernel_gettimeofday; > __kernel_clock_gettime; > __kernel_clock_getres; > + /* ADD YOUR VDSO STUFF HERE */ > + perf_read_counter; > + __vdso_perf_read_counter; > + perf_open_counter; > + __vdso_perf_open_counter; > local: *; > }; > } > diff --git a/arch/arm64/kernel/vdso/vdso_perfc.c > b/arch/arm64/kernel/vdso/vdso_perfc.c > new file mode 100644 > index 0000000..c363d64 > --- /dev/null > +++ b/arch/arm64/kernel/vdso/vdso_perfc.c > @@ -0,0 +1,20 @@ > +#include <linux/compiler.h> > + > +int perf_read_counter(void) > + __attribute__((weak, alias("__vdso__perf_read_counter"))); > +int perf_open_counter(void) > + __attribute__((weak, alias("__vdso__perf_open_counter"))); > + > +#define ARMV8_PMCNTENSET_EL0_ENABLE (1<<31) /**< Enable Perf count reg */ > + > +__attribute__((no_instrument_function)) int > __vdso__perf_read_counter(void) > +{ > +int ret = 0; > +asm volatile("mrs %0, pmccntr_el0" : "=r" (ret)); > +return ret; > +} > + > +__attribute__((no_instrument_function)) void > __vdso__perf_open_counter(void) > +{ > +asm volatile("msr pmcntenset_el0, %0" : : "r" > (ARMV8_PMCNTENSET_EL0_ENABLE)); > +} > -- > 1.7.9.5 > > > _______________________________________________ > lng-odp mailing list > lng-odp@lists.linaro.org > http://lists.linaro.org/mailman/listinfo/lng-odp >
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index 6d20b7d..4fde490 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -5,7 +5,7 @@ # Heavily based on the vDSO Makefiles for other archs. # -obj-vdso := gettimeofday.o note.o sigreturn.o +obj-vdso := gettimeofday.o note.o sigreturn.o armpmu.o # Build rules targets := $(obj-vdso) vdso.so vdso.so.dbg @@ -43,8 +43,8 @@ $(obj)/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE $(call if_changed,vdsosym) # Assembly rules for the .S files -$(obj-vdso): %.o: %.S - $(call if_changed_dep,vdsoas) +#$(obj-vdso): %.o: %.S +# $(call if_changed_dep,vdsoas) # Actual build commands quiet_cmd_vdsold = VDSOL $@ diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S index 8154b8d..8cb56e0 100644 --- a/arch/arm64/kernel/vdso/vdso.lds.S +++ b/arch/arm64/kernel/vdso/vdso.lds.S @@ -90,6 +90,11 @@ VERSION __kernel_gettimeofday; __kernel_clock_gettime; __kernel_clock_getres; + /* ADD YOUR VDSO STUFF HERE */ + perf_read_counter; + __vdso_perf_read_counter; + perf_open_counter; + __vdso_perf_open_counter; local: *; }; } diff --git a/arch/arm64/kernel/vdso/vdso_perfc.c b/arch/arm64/kernel/vdso/vdso_perfc.c new file mode 100644 index 0000000..c363d64 --- /dev/null +++ b/arch/arm64/kernel/vdso/vdso_perfc.c @@ -0,0 +1,20 @@ +#include <linux/compiler.h> + +int perf_read_counter(void) + __attribute__((weak, alias("__vdso__perf_read_counter"))); +int perf_open_counter(void) + __attribute__((weak, alias("__vdso__perf_open_counter"))); + +#define ARMV8_PMCNTENSET_EL0_ENABLE (1<<31) /**< Enable Perf count reg */ + +__attribute__((no_instrument_function)) int __vdso__perf_read_counter(void) +{ +int ret = 0; +asm volatile("mrs %0, pmccntr_el0" : "=r" (ret)); +return ret; +} + +__attribute__((no_instrument_function)) void __vdso__perf_open_counter(void) +{ +asm volatile("msr pmcntenset_el0, %0" : : "r" (ARMV8_PMCNTENSET_EL0_ENABLE)); +}
Signed-off-by: Yogesh Tillu <yogesh.tillu@linaro.org> --- arch/arm64/kernel/vdso/Makefile | 6 +++--- arch/arm64/kernel/vdso/vdso.lds.S | 5 +++++ arch/arm64/kernel/vdso/vdso_perfc.c | 20 ++++++++++++++++++++ 3 files changed, 28 insertions(+), 3 deletions(-) create mode 100644 arch/arm64/kernel/vdso/vdso_perfc.c