diff options
| -rw-r--r-- | arch/x86/oprofile/op_model_amd.c | 69 |
1 files changed, 63 insertions, 6 deletions
diff --git a/arch/x86/oprofile/op_model_amd.c b/arch/x86/oprofile/op_model_amd.c index 97c84ebe3f24..a9d194734a8e 100644 --- a/arch/x86/oprofile/op_model_amd.c +++ b/arch/x86/oprofile/op_model_amd.c @@ -52,7 +52,7 @@ static unsigned long reset_value[NUM_VIRT_COUNTERS]; #define IBS_FETCH_ENABLE (1ULL<<48) #define IBS_FETCH_CNT_MASK 0xFFFF0000ULL -/*IbsOpCtl bits */ +/* IbsOpCtl bits */ #define IBS_OP_CNT_CTL (1ULL<<19) #define IBS_OP_VAL (1ULL<<18) #define IBS_OP_ENABLE (1ULL<<17) @@ -72,6 +72,7 @@ struct op_ibs_config { }; static struct op_ibs_config ibs_config; +static u64 ibs_op_ctl; /* * IBS cpuid feature detection @@ -84,8 +85,16 @@ static struct op_ibs_config ibs_config; * bit 0 is used to indicate the existence of IBS. */ #define IBS_CAPS_AVAIL (1LL<<0) +#define IBS_CAPS_RDWROPCNT (1LL<<3) #define IBS_CAPS_OPCNT (1LL<<4) +/* + * IBS randomization macros + */ +#define IBS_RANDOM_BITS 12 +#define IBS_RANDOM_MASK ((1ULL << IBS_RANDOM_BITS) - 1) +#define IBS_RANDOM_MAXCNT_OFFSET (1ULL << (IBS_RANDOM_BITS - 5)) + static u32 get_ibs_caps(void) { u32 ibs_caps; @@ -241,6 +250,38 @@ static unsigned int lfsr_random(void) return lfsr_value; } +/* + * IBS software randomization + * + * The IBS periodic op counter is randomized in software. The lower 12 + * bits of the 20 bit counter are randomized. IbsOpCurCnt is + * initialized with a 12 bit random value. + */ +static inline u64 op_amd_randomize_ibs_op(u64 val) +{ + unsigned int random = lfsr_random(); + + if (!(ibs_caps & IBS_CAPS_RDWROPCNT)) + /* + * Work around if the hw can not write to IbsOpCurCnt + * + * Randomize the lower 8 bits of the 16 bit + * IbsOpMaxCnt [15:0] value in the range of -128 to + * +127 by adding/subtracting an offset to the + * maximum count (IbsOpMaxCnt). + * + * To avoid over or underflows and protect upper bits + * starting at bit 16, the initial value for + * IbsOpMaxCnt must fit in the range from 0x0081 to + * 0xff80. + */ + val += (s8)(random >> 4); + else + val |= (u64)(random & IBS_RANDOM_MASK) << 32; + + return val; +} + static inline void op_amd_handle_ibs(struct pt_regs * const regs, struct op_msrs const * const msrs) @@ -290,8 +331,7 @@ op_amd_handle_ibs(struct pt_regs * const regs, oprofile_write_commit(&entry); /* reenable the IRQ */ - ctl &= ~IBS_OP_VAL & 0xFFFFFFFF; - ctl |= IBS_OP_ENABLE; + ctl = op_amd_randomize_ibs_op(ibs_op_ctl); wrmsrl(MSR_AMD64_IBSOPCTL, ctl); } } @@ -312,10 +352,27 @@ static inline void op_amd_start_ibs(void) } if (ibs_config.op_enabled) { - val = (ibs_config.max_cnt_op >> 4) & 0xFFFF; + ibs_op_ctl = ibs_config.max_cnt_op >> 4; + if (!(ibs_caps & IBS_CAPS_RDWROPCNT)) { + /* + * IbsOpCurCnt not supported. See + * op_amd_randomize_ibs_op() for details. + */ + ibs_op_ctl = clamp(ibs_op_ctl, 0x0081ULL, 0xFF80ULL); + } else { + /* + * The start value is randomized with a + * positive offset, we need to compensate it + * with the half of the randomized range. Also + * avoid underflows. + */ + ibs_op_ctl = min(ibs_op_ctl + IBS_RANDOM_MAXCNT_OFFSET, + 0xFFFFULL); + } if (ibs_caps & IBS_CAPS_OPCNT && ibs_config.dispatched_ops) - val |= IBS_OP_CNT_CTL; - val |= IBS_OP_ENABLE; + ibs_op_ctl |= IBS_OP_CNT_CTL; + ibs_op_ctl |= IBS_OP_ENABLE; + val = op_amd_randomize_ibs_op(ibs_op_ctl); wrmsrl(MSR_AMD64_IBSOPCTL, val); } } |