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-rw-r--r--arch/x86/oprofile/backtrace.c56
1 files changed, 47 insertions, 9 deletions
diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index a5b64ab4cd6e..32f78eb46744 100644
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -11,10 +11,12 @@
#include <linux/oprofile.h>
#include <linux/sched.h>
#include <linux/mm.h>
+#include <linux/compat.h>
+#include <linux/highmem.h>
+
#include <asm/ptrace.h>
#include <asm/uaccess.h>
#include <asm/stacktrace.h>
-#include <linux/compat.h>
static int backtrace_stack(void *data, char *name)
{
@@ -36,17 +38,53 @@ static struct stacktrace_ops backtrace_ops = {
.walk_stack = print_context_stack,
};
+/* from arch/x86/kernel/cpu/perf_event.c: */
+
+/*
+ * 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;
+ unsigned long size, len = 0;
+ struct page *page;
+ void *map;
+ int ret;
+
+ do {
+ ret = __get_user_pages_fast(addr, 1, 0, &page);
+ if (!ret)
+ break;
+
+ offset = addr & (PAGE_SIZE - 1);
+ size = min(PAGE_SIZE - offset, n - len);
+
+ map = kmap_atomic(page);
+ memcpy(to, map+offset, size);
+ kunmap_atomic(map);
+ put_page(page);
+
+ len += size;
+ to += size;
+ addr += size;
+
+ } while (len < n);
+
+ return len;
+}
+
#ifdef CONFIG_COMPAT
static struct stack_frame_ia32 *
dump_user_backtrace_32(struct stack_frame_ia32 *head)
{
+ /* Also check accessibility of one struct frame_head beyond: */
struct stack_frame_ia32 bufhead[2];
struct stack_frame_ia32 *fp;
+ unsigned long bytes;
- /* Also check accessibility of one struct frame_head beyond */
- if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
- return NULL;
- if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
+ bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
+ if (bytes != sizeof(bufhead))
return NULL;
fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
@@ -87,12 +125,12 @@ x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
{
+ /* Also check accessibility of one struct frame_head beyond: */
struct stack_frame bufhead[2];
+ unsigned long bytes;
- /* Also check accessibility of one struct stack_frame beyond */
- if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
- return NULL;
- if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
+ bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
+ if (bytes != sizeof(bufhead))
return NULL;
oprofile_add_trace(bufhead[0].return_address);