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Subject[PATCH v3 18/24] arm64/debug: Make use of the system wide safe value
Date
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(-)

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);
}

/*
--
1.7.9.5


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