diff options
Diffstat (limited to 'arch/x86/events/intel/lbr.c')
| -rw-r--r-- | arch/x86/events/intel/lbr.c | 124 |
1 files changed, 106 insertions, 18 deletions
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c index 9e2b40c..707d358 100644 --- a/arch/x86/events/intel/lbr.c +++ b/arch/x86/events/intel/lbr.c @@ -77,9 +77,11 @@ static enum { LBR_IND_JMP |\ LBR_FAR) -#define LBR_FROM_FLAG_MISPRED (1ULL << 63) -#define LBR_FROM_FLAG_IN_TX (1ULL << 62) -#define LBR_FROM_FLAG_ABORT (1ULL << 61) +#define LBR_FROM_FLAG_MISPRED BIT_ULL(63) +#define LBR_FROM_FLAG_IN_TX BIT_ULL(62) +#define LBR_FROM_FLAG_ABORT BIT_ULL(61) + +#define LBR_FROM_SIGNEXT_2MSB (BIT_ULL(60) | BIT_ULL(59)) /* * x86control flow change classification @@ -235,6 +237,97 @@ enum { LBR_VALID, }; +/* + * For formats with LBR_TSX flags (e.g. LBR_FORMAT_EIP_FLAGS2), bits 61:62 in + * MSR_LAST_BRANCH_FROM_x are the TSX flags when TSX is supported, but when + * TSX is not supported they have no consistent behavior: + * + * - For wrmsr(), bits 61:62 are considered part of the sign extension. + * - For HW updates (branch captures) bits 61:62 are always OFF and are not + * part of the sign extension. + * + * Therefore, if: + * + * 1) LBR has TSX format + * 2) CPU has no TSX support enabled + * + * ... then any value passed to wrmsr() must be sign extended to 63 bits and any + * value from rdmsr() must be converted to have a 61 bits sign extension, + * ignoring the TSX flags. + */ +static inline bool lbr_from_signext_quirk_needed(void) +{ + int lbr_format = x86_pmu.intel_cap.lbr_format; + bool tsx_support = boot_cpu_has(X86_FEATURE_HLE) || + boot_cpu_has(X86_FEATURE_RTM); + + return !tsx_support && (lbr_desc[lbr_format] & LBR_TSX); +} + +DEFINE_STATIC_KEY_FALSE(lbr_from_quirk_key); + +/* If quirk is enabled, ensure sign extension is 63 bits: */ +inline u64 lbr_from_signext_quirk_wr(u64 val) +{ + if (static_branch_unlikely(&lbr_from_quirk_key)) { + /* + * Sign extend into bits 61:62 while preserving bit 63. + * + * Quirk is enabled when TSX is disabled. Therefore TSX bits + * in val are always OFF and must be changed to be sign + * extension bits. Since bits 59:60 are guaranteed to be + * part of the sign extension bits, we can just copy them + * to 61:62. + */ + val |= (LBR_FROM_SIGNEXT_2MSB & val) << 2; + } + return val; +} + +/* + * If quirk is needed, ensure sign extension is 61 bits: + */ +u64 lbr_from_signext_quirk_rd(u64 val) +{ + if (static_branch_unlikely(&lbr_from_quirk_key)) { + /* + * Quirk is on when TSX is not enabled. Therefore TSX + * flags must be read as OFF. + */ + val &= ~(LBR_FROM_FLAG_IN_TX | LBR_FROM_FLAG_ABORT); + } + return val; +} + +static inline void wrlbr_from(unsigned int idx, u64 val) +{ + val = lbr_from_signext_quirk_wr(val); + wrmsrl(x86_pmu.lbr_from + idx, val); +} + +static inline void wrlbr_to(unsigned int idx, u64 val) +{ + wrmsrl(x86_pmu.lbr_to + idx, val); +} + +static inline u64 rdlbr_from(unsigned int idx) +{ + u64 val; + + rdmsrl(x86_pmu.lbr_from + idx, val); + + return lbr_from_signext_quirk_rd(val); +} + +static inline u64 rdlbr_to(unsigned int idx) +{ + u64 val; + + rdmsrl(x86_pmu.lbr_to + idx, val); + + return val; +} + static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx) { int i; @@ -251,8 +344,9 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx) tos = task_ctx->tos; for (i = 0; i < tos; i++) { lbr_idx = (tos - i) & mask; - wrmsrl(x86_pmu.lbr_from + lbr_idx, task_ctx->lbr_from[i]); - wrmsrl(x86_pmu.lbr_to + lbr_idx, task_ctx->lbr_to[i]); + wrlbr_from(lbr_idx, task_ctx->lbr_from[i]); + wrlbr_to (lbr_idx, task_ctx->lbr_to[i]); + if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO) wrmsrl(MSR_LBR_INFO_0 + lbr_idx, task_ctx->lbr_info[i]); } @@ -262,9 +356,9 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx) static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx) { - int i; unsigned lbr_idx, mask; u64 tos; + int i; if (task_ctx->lbr_callstack_users == 0) { task_ctx->lbr_stack_state = LBR_NONE; @@ -275,8 +369,8 @@ static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx) tos = intel_pmu_lbr_tos(); for (i = 0; i < tos; i++) { lbr_idx = (tos - i) & mask; - rdmsrl(x86_pmu.lbr_from + lbr_idx, task_ctx->lbr_from[i]); - rdmsrl(x86_pmu.lbr_to + lbr_idx, task_ctx->lbr_to[i]); + task_ctx->lbr_from[i] = rdlbr_from(lbr_idx); + task_ctx->lbr_to[i] = rdlbr_to(lbr_idx); if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO) rdmsrl(MSR_LBR_INFO_0 + lbr_idx, task_ctx->lbr_info[i]); } @@ -452,8 +546,8 @@ static void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc) u16 cycles = 0; int lbr_flags = lbr_desc[lbr_format]; - rdmsrl(x86_pmu.lbr_from + lbr_idx, from); - rdmsrl(x86_pmu.lbr_to + lbr_idx, to); + from = rdlbr_from(lbr_idx); + to = rdlbr_to(lbr_idx); if (lbr_format == LBR_FORMAT_INFO && need_info) { u64 info; @@ -956,7 +1050,6 @@ void __init intel_pmu_lbr_init_core(void) * SW branch filter usage: * - compensate for lack of HW filter */ - pr_cont("4-deep LBR, "); } /* nehalem/westmere */ @@ -977,7 +1070,6 @@ void __init intel_pmu_lbr_init_nhm(void) * That requires LBR_FAR but that means far * jmp need to be filtered out */ - pr_cont("16-deep LBR, "); } /* sandy bridge */ @@ -997,7 +1089,6 @@ void __init intel_pmu_lbr_init_snb(void) * That requires LBR_FAR but that means far * jmp need to be filtered out */ - pr_cont("16-deep LBR, "); } /* haswell */ @@ -1011,7 +1102,8 @@ void intel_pmu_lbr_init_hsw(void) x86_pmu.lbr_sel_mask = LBR_SEL_MASK; x86_pmu.lbr_sel_map = hsw_lbr_sel_map; - pr_cont("16-deep LBR, "); + if (lbr_from_signext_quirk_needed()) + static_branch_enable(&lbr_from_quirk_key); } /* skylake */ @@ -1031,7 +1123,6 @@ __init void intel_pmu_lbr_init_skl(void) * That requires LBR_FAR but that means far * jmp need to be filtered out */ - pr_cont("32-deep LBR, "); } /* atom */ @@ -1057,7 +1148,6 @@ void __init intel_pmu_lbr_init_atom(void) * SW branch filter usage: * - compensate for lack of HW filter */ - pr_cont("8-deep LBR, "); } /* slm */ @@ -1088,6 +1178,4 @@ void intel_pmu_lbr_init_knl(void) x86_pmu.lbr_sel_mask = LBR_SEL_MASK; x86_pmu.lbr_sel_map = snb_lbr_sel_map; - - pr_cont("8-deep LBR, "); } |
