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Subject[PATCH 1/3] perf/x86/amd: AMD support for bp_len > HW_BREAKPOINT_LEN_8
Date
From: Jacob Shin <jacob.w.shin@gmail.com>

Implement hardware breakpoint address mask for AMD Family 16h and
above processors. CPUID feature bit indicates hardware support for
DRn_ADDR_MASK MSRs. These masks further qualify DRn/DR7 hardware
breakpoint addresses to allow matching of larger addresses ranges.

Valuable advice and pseudo code from Oleg Nesterov <oleg@redhat.com>

Signed-off-by: Jacob Shin <jacob.w.shin@gmail.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/include/asm/cpufeature.h | 2 ++
arch/x86/include/asm/debugreg.h | 5 ++++
arch/x86/include/asm/hw_breakpoint.h | 1 +
arch/x86/include/uapi/asm/msr-index.h | 4 +++
arch/x86/kernel/cpu/amd.c | 19 ++++++++++++++
arch/x86/kernel/hw_breakpoint.c | 47 ++++++++++++++---------------------
6 files changed, 49 insertions(+), 29 deletions(-)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index d3f5c63..26609bb 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -170,6 +170,7 @@
#define X86_FEATURE_TOPOEXT (6*32+22) /* topology extensions CPUID leafs */
#define X86_FEATURE_PERFCTR_CORE (6*32+23) /* core performance counter extensions */
#define X86_FEATURE_PERFCTR_NB (6*32+24) /* NB performance counter extensions */
+#define X86_FEATURE_BPEXT (6*32+26) /* data breakpoint extension */
#define X86_FEATURE_PERFCTR_L2 (6*32+28) /* L2 performance counter extensions */

/*
@@ -332,6 +333,7 @@ extern const char * const x86_power_flags[32];
#define cpu_has_cx16 boot_cpu_has(X86_FEATURE_CX16)
#define cpu_has_eager_fpu boot_cpu_has(X86_FEATURE_EAGER_FPU)
#define cpu_has_topoext boot_cpu_has(X86_FEATURE_TOPOEXT)
+#define cpu_has_bpext boot_cpu_has(X86_FEATURE_BPEXT)

#ifdef CONFIG_X86_64

diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index 4b528a9..145b009 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -114,5 +114,10 @@ static inline void debug_stack_usage_inc(void) { }
static inline void debug_stack_usage_dec(void) { }
#endif /* X86_64 */

+#ifdef CONFIG_CPU_SUP_AMD
+extern void set_dr_addr_mask(unsigned long mask, int dr);
+#else
+static inline void set_dr_addr_mask(unsigned long mask, int dr) { }
+#endif

#endif /* _ASM_X86_DEBUGREG_H */
diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h
index ef1c4d2..6c98be8 100644
--- a/arch/x86/include/asm/hw_breakpoint.h
+++ b/arch/x86/include/asm/hw_breakpoint.h
@@ -12,6 +12,7 @@
*/
struct arch_hw_breakpoint {
unsigned long address;
+ unsigned long mask;
u8 len;
u8 type;
};
diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h
index bb04650..1f04f6c 100644
--- a/arch/x86/include/uapi/asm/msr-index.h
+++ b/arch/x86/include/uapi/asm/msr-index.h
@@ -205,6 +205,10 @@
/* Fam 16h MSRs */
#define MSR_F16H_L2I_PERF_CTL 0xc0010230
#define MSR_F16H_L2I_PERF_CTR 0xc0010231
+#define MSR_F16H_DR1_ADDR_MASK 0xc0011019
+#define MSR_F16H_DR2_ADDR_MASK 0xc001101a
+#define MSR_F16H_DR3_ADDR_MASK 0xc001101b
+#define MSR_F16H_DR0_ADDR_MASK 0xc0011027

/* Fam 15h MSRs */
#define MSR_F15H_PERF_CTL 0xc0010200
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 903a264..fffc9cb 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -909,3 +909,22 @@ static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum)

return false;
}
+
+void set_dr_addr_mask(unsigned long mask, int dr)
+{
+ if (!cpu_has_bpext)
+ return;
+
+ switch (dr) {
+ case 0:
+ wrmsr(MSR_F16H_DR0_ADDR_MASK, mask, 0);
+ break;
+ case 1:
+ case 2:
+ case 3:
+ wrmsr(MSR_F16H_DR1_ADDR_MASK - 1 + dr, mask, 0);
+ break;
+ default:
+ break;
+ }
+}
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index f66ff16..3cb1951 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -128,6 +128,8 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
*dr7 |= encode_dr7(i, info->len, info->type);

set_debugreg(*dr7, 7);
+ if (info->mask)
+ set_dr_addr_mask(info->mask, i);

return 0;
}
@@ -163,29 +165,8 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
*dr7 &= ~__encode_dr7(i, info->len, info->type);

set_debugreg(*dr7, 7);
-}
-
-static int get_hbp_len(u8 hbp_len)
-{
- unsigned int len_in_bytes = 0;
-
- switch (hbp_len) {
- case X86_BREAKPOINT_LEN_1:
- len_in_bytes = 1;
- break;
- case X86_BREAKPOINT_LEN_2:
- len_in_bytes = 2;
- break;
- case X86_BREAKPOINT_LEN_4:
- len_in_bytes = 4;
- break;
-#ifdef CONFIG_X86_64
- case X86_BREAKPOINT_LEN_8:
- len_in_bytes = 8;
- break;
-#endif
- }
- return len_in_bytes;
+ if (info->mask)
+ set_dr_addr_mask(0, i);
}

/*
@@ -198,7 +179,7 @@ int arch_check_bp_in_kernelspace(struct perf_event *bp)
struct arch_hw_breakpoint *info = counter_arch_bp(bp);

va = info->address;
- len = get_hbp_len(info->len);
+ len = bp->attr.bp_len;

return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
}
@@ -279,7 +260,16 @@ static int arch_build_bp_info(struct perf_event *bp)
}

/* Len */
+ info->mask = 0;
+
switch (bp->attr.bp_len) {
+ default:
+ if (!is_power_of_2(bp->attr.bp_len))
+ return -EINVAL;
+ if (!cpu_has_bpext)
+ return -EOPNOTSUPP;
+ info->mask = bp->attr.bp_len - 1;
+ /* fall through */
case HW_BREAKPOINT_LEN_1:
info->len = X86_BREAKPOINT_LEN_1;
break;
@@ -294,12 +284,11 @@ static int arch_build_bp_info(struct perf_event *bp)
info->len = X86_BREAKPOINT_LEN_8;
break;
#endif
- default:
- return -EINVAL;
}

return 0;
}
+
/*
* Validate the arch-specific HW Breakpoint register settings
*/
@@ -314,11 +303,11 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
if (ret)
return ret;

- ret = -EINVAL;
-
switch (info->len) {
case X86_BREAKPOINT_LEN_1:
align = 0;
+ if (info->mask)
+ align = info->mask;
break;
case X86_BREAKPOINT_LEN_2:
align = 1;
@@ -332,7 +321,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
break;
#endif
default:
- return ret;
+ BUG();
}

/*
--
1.8.1.2



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