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-rw-r--r--arch/x86/kernel/cpu/perf_counter.c49
1 files changed, 39 insertions, 10 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 6d5e7cfd97e..e8c68a5091d 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -19,6 +19,7 @@
#include <linux/kdebug.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
+#include <linux/highmem.h>
#include <asm/apic.h>
#include <asm/stacktrace.h>
@@ -1617,20 +1618,48 @@ perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
entry->kernel = entry->nr - nr;
}
-static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
+/*
+ * best effort, GUP based copy_from_user() that assumes IRQ or NMI context
+ */
+static unsigned long
+copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
{
+ unsigned long offset, addr = (unsigned long)from;
+ int type = in_nmi() ? KM_NMI : KM_IRQ0;
+ unsigned long size, len = 0;
+ struct page *page;
+ void *map;
int ret;
- if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
- return 0;
+ do {
+ ret = __get_user_pages_fast(addr, 1, 0, &page);
+ if (!ret)
+ break;
- ret = 1;
- pagefault_disable();
- if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
- ret = 0;
- pagefault_enable();
+ offset = addr & (PAGE_SIZE - 1);
+ size = min(PAGE_SIZE - offset, n - len);
- return ret;
+ map = kmap_atomic(page, type);
+ memcpy(to, map+offset, size);
+ kunmap_atomic(map, type);
+ put_page(page);
+
+ len += size;
+ to += size;
+ addr += size;
+
+ } while (len < n);
+
+ return len;
+}
+
+static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
+{
+ unsigned long bytes;
+
+ bytes = copy_from_user_nmi(frame, fp, sizeof(*frame));
+
+ return bytes == sizeof(*frame);
}
static void
@@ -1643,7 +1672,7 @@ perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
if (!user_mode(regs))
regs = task_pt_regs(current);
- fp = (void __user *)regs->bp;
+ fp = (void __user *)regs->bp;
callchain_store(entry, regs->ip);