diff options
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event.h')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.h | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index 821d53b696d..6605a81ba33 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -516,6 +516,26 @@ static inline bool kernel_ip(unsigned long ip) #endif } +/* + * Not all PMUs provide the right context information to place the reported IP + * into full context. Specifically segment registers are typically not + * supplied. + * + * Assuming the address is a linear address (it is for IBS), we fake the CS and + * vm86 mode using the known zero-based code segment and 'fix up' the registers + * to reflect this. + * + * Intel PEBS/LBR appear to typically provide the effective address, nothing + * much we can do about that but pray and treat it like a linear address. + */ +static inline void set_linear_ip(struct pt_regs *regs, unsigned long ip) +{ + regs->cs = kernel_ip(ip) ? __KERNEL_CS : __USER_CS; + if (regs->flags & X86_VM_MASK) + regs->flags ^= (PERF_EFLAGS_VM | X86_VM_MASK); + regs->ip = ip; +} + #ifdef CONFIG_CPU_SUP_AMD int amd_pmu_init(void); |