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Diffstat (limited to 'arch/x86/kernel/cpu/perf_event.c')
-rw-r--r--arch/x86/kernel/cpu/perf_event.c89
1 files changed, 79 insertions, 10 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 29557aa06dda..915b876edd1e 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -32,6 +32,8 @@
#include <asm/smp.h>
#include <asm/alternative.h>
#include <asm/timer.h>
+#include <asm/desc.h>
+#include <asm/ldt.h>
#include "perf_event.h"
@@ -1738,6 +1740,29 @@ valid_user_frame(const void __user *fp, unsigned long size)
return (__range_not_ok(fp, size, TASK_SIZE) == 0);
}
+static unsigned long get_segment_base(unsigned int segment)
+{
+ struct desc_struct *desc;
+ int idx = segment >> 3;
+
+ if ((segment & SEGMENT_TI_MASK) == SEGMENT_LDT) {
+ if (idx > LDT_ENTRIES)
+ return 0;
+
+ if (idx > current->active_mm->context.size)
+ return 0;
+
+ desc = current->active_mm->context.ldt;
+ } else {
+ if (idx > GDT_ENTRIES)
+ return 0;
+
+ desc = __this_cpu_ptr(&gdt_page.gdt[0]);
+ }
+
+ return get_desc_base(desc + idx);
+}
+
#ifdef CONFIG_COMPAT
#include <asm/compat.h>
@@ -1746,13 +1771,17 @@ static inline int
perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
/* 32-bit process in 64-bit kernel. */
+ unsigned long ss_base, cs_base;
struct stack_frame_ia32 frame;
const void __user *fp;
if (!test_thread_flag(TIF_IA32))
return 0;
- fp = compat_ptr(regs->bp);
+ cs_base = get_segment_base(regs->cs);
+ ss_base = get_segment_base(regs->ss);
+
+ fp = compat_ptr(ss_base + regs->bp);
while (entry->nr < PERF_MAX_STACK_DEPTH) {
unsigned long bytes;
frame.next_frame = 0;
@@ -1765,8 +1794,8 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
if (!valid_user_frame(fp, sizeof(frame)))
break;
- perf_callchain_store(entry, frame.return_address);
- fp = compat_ptr(frame.next_frame);
+ perf_callchain_store(entry, cs_base + frame.return_address);
+ fp = compat_ptr(ss_base + frame.next_frame);
}
return 1;
}
@@ -1789,6 +1818,12 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
return;
}
+ /*
+ * We don't know what to do with VM86 stacks.. ignore them for now.
+ */
+ if (regs->flags & (X86_VM_MASK | PERF_EFLAGS_VM))
+ return;
+
fp = (void __user *)regs->bp;
perf_callchain_store(entry, regs->ip);
@@ -1816,16 +1851,50 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
}
}
-unsigned long perf_instruction_pointer(struct pt_regs *regs)
+/*
+ * Deal with code segment offsets for the various execution modes:
+ *
+ * VM86 - the good olde 16 bit days, where the linear address is
+ * 20 bits and we use regs->ip + 0x10 * regs->cs.
+ *
+ * IA32 - Where we need to look at GDT/LDT segment descriptor tables
+ * to figure out what the 32bit base address is.
+ *
+ * X32 - has TIF_X32 set, but is running in x86_64
+ *
+ * X86_64 - CS,DS,SS,ES are all zero based.
+ */
+static unsigned long code_segment_base(struct pt_regs *regs)
{
- unsigned long ip;
+ /*
+ * If we are in VM86 mode, add the segment offset to convert to a
+ * linear address.
+ */
+ if (regs->flags & X86_VM_MASK)
+ return 0x10 * regs->cs;
+
+ /*
+ * For IA32 we look at the GDT/LDT segment base to convert the
+ * effective IP to a linear address.
+ */
+#ifdef CONFIG_X86_32
+ if (user_mode(regs) && regs->cs != __USER_CS)
+ return get_segment_base(regs->cs);
+#else
+ if (test_thread_flag(TIF_IA32)) {
+ if (user_mode(regs) && regs->cs != __USER32_CS)
+ return get_segment_base(regs->cs);
+ }
+#endif
+ return 0;
+}
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
- ip = perf_guest_cbs->get_guest_ip();
- else
- ip = instruction_pointer(regs);
+ return perf_guest_cbs->get_guest_ip();
- return ip;
+ return regs->ip + code_segment_base(regs);
}
unsigned long perf_misc_flags(struct pt_regs *regs)
@@ -1838,7 +1907,7 @@ unsigned long perf_misc_flags(struct pt_regs *regs)
else
misc |= PERF_RECORD_MISC_GUEST_KERNEL;
} else {
- if (!kernel_ip(regs->ip))
+ if (user_mode(regs))
misc |= PERF_RECORD_MISC_USER;
else
misc |= PERF_RECORD_MISC_KERNEL;