| Message ID | 1444064531-25607-17-git-send-email-suzuki.poulose@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Oct 05, 2015 at 06:02:05PM +0100, Suzuki K. Poulose wrote: > @@ -137,13 +138,17 @@ extern struct pmu perf_ops_bp; > /* Determine number of BRP registers available. */ > static inline int get_num_brps(void) > { > - return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1; > + return 1 + > + cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1), > + ID_AA64DFR0_BRPS_SHIFT); > } cpuid_feature_extract_field() is fine but we should we bother with read_system_reg vs just read_cpuid? Similar question for patch 17/22.
On 08/10/15 12:11, Catalin Marinas wrote: > On Mon, Oct 05, 2015 at 06:02:05PM +0100, Suzuki K. Poulose wrote: >> @@ -137,13 +138,17 @@ extern struct pmu perf_ops_bp; >> /* Determine number of BRP registers available. */ >> static inline int get_num_brps(void) >> { >> - return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1; >> + return 1 + >> + cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1), >> + ID_AA64DFR0_BRPS_SHIFT); >> } > > cpuid_feature_extract_field() is fine but we should we bother with > read_system_reg vs just read_cpuid? > Similar question for patch 17/22. Well, we would have already TAINTed the kernel, if these fields are different. It is just the matter of, whether we want to provide the safer value on a tainted kernel or not. I am open to suggestions. Thanks Suzuki
On Thu, Oct 08, 2015 at 12:56:28PM +0100, Suzuki K. Poulose wrote: > On 08/10/15 12:11, Catalin Marinas wrote: > >On Mon, Oct 05, 2015 at 06:02:05PM +0100, Suzuki K. Poulose wrote: > >>@@ -137,13 +138,17 @@ extern struct pmu perf_ops_bp; > >> /* Determine number of BRP registers available. */ > >> static inline int get_num_brps(void) > >> { > >>- return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1; > >>+ return 1 + > >>+ cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1), > >>+ ID_AA64DFR0_BRPS_SHIFT); > >> } > > > >cpuid_feature_extract_field() is fine but we should we bother with > >read_system_reg vs just read_cpuid? > >Similar question for patch 17/22. > > Well, we would have already TAINTed the kernel, if these fields are different. > It is just the matter of, whether we want to provide the safer value on a tainted > kernel or not. I am open to suggestions. Ah, sorry, I mixed read_system_reg() with read_cpu_sysreg(). I think we need to rename the latter as it gets confusing. Maybe something like read_native_sys_reg() or __raw_read_system_reg().
On 08/10/15 16:08, Catalin Marinas wrote: > On Thu, Oct 08, 2015 at 12:56:28PM +0100, Suzuki K. Poulose wrote: >> On 08/10/15 12:11, Catalin Marinas wrote: >>> On Mon, Oct 05, 2015 at 06:02:05PM +0100, Suzuki K. Poulose wrote: >>>> @@ -137,13 +138,17 @@ extern struct pmu perf_ops_bp; >>>> /* Determine number of BRP registers available. */ >>>> static inline int get_num_brps(void) >>>> { >>>> - return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1; >>>> + return 1 + >>>> + cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1), >>>> + ID_AA64DFR0_BRPS_SHIFT); >>>> } >>> >>> cpuid_feature_extract_field() is fine but we should we bother with >>> read_system_reg vs just read_cpuid? >>> Similar question for patch 17/22. >> >> Well, we would have already TAINTed the kernel, if these fields are different. >> It is just the matter of, whether we want to provide the safer value on a tainted >> kernel or not. I am open to suggestions. > > Ah, sorry, I mixed read_system_reg() with read_cpu_sysreg(). I think we Oh, ok. I think we should rename it as you suggest below to avoid the confusion. > need to rename the latter as it gets confusing. Maybe something like > read_native_sys_reg() or __raw_read_system_reg(). > Thanks Suzuki
diff --git a/arch/arm64/include/asm/hw_breakpoint.h b/arch/arm64/include/asm/hw_breakpoint.h index 4c47cb2..e54415e 100644 --- a/arch/arm64/include/asm/hw_breakpoint.h +++ b/arch/arm64/include/asm/hw_breakpoint.h @@ -17,6 +17,7 @@ #define __ASM_HW_BREAKPOINT_H #include <asm/cputype.h> +#include <asm/cpufeature.h> #ifdef __KERNEL__ @@ -137,13 +138,17 @@ extern struct pmu perf_ops_bp; /* Determine number of BRP registers available. */ static inline int get_num_brps(void) { - return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1; + return 1 + + cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1), + ID_AA64DFR0_BRPS_SHIFT); } /* Determine number of WRP registers available. */ static inline int get_num_wrps(void) { - return ((read_cpuid(ID_AA64DFR0_EL1) >> 20) & 0xf) + 1; + return 1 + + cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1), + ID_AA64DFR0_WRPS_SHIFT); } #endif /* __KERNEL__ */ diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index cebf786..c0a2327 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -26,14 +26,16 @@ #include <linux/stat.h> #include <linux/uaccess.h> -#include <asm/debug-monitors.h> +#include <asm/cpufeature.h> #include <asm/cputype.h> +#include <asm/debug-monitors.h> #include <asm/system_misc.h> /* Determine debug architecture. */ u8 debug_monitors_arch(void) { - return read_cpuid(ID_AA64DFR0_EL1) & 0xf; + return cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1), + ID_AA64DFR0_DEBUGVER_SHIFT); } /*
Use the system wide value of ID_AA64DFR0 to make safer decisions Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com> --- arch/arm64/include/asm/hw_breakpoint.h | 9 +++++++-- arch/arm64/kernel/debug-monitors.c | 6 ++++-- 2 files changed, 11 insertions(+), 4 deletions(-)