[PATCH] unwinder: Use probe_kernel_address instead of __get_user in kernel/unwind.c

This avoids trouble with the page fault handler if the fault
happens inside an interrupt context.

Suggested by Linus

Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>

diff --git a/kernel/unwind.c b/kernel/unwind.c
index ed0a21d4a902339acef700eea0e291220ce7fb2a..af48168a3afbd91408da9bcc487cdc345f4a3086 100644 (file)
--- a/kernel/unwind.c
+++ b/kernel/unwind.c
@@ -14,6 +14,7 @@
 #include <linux/bootmem.h>
 #include <linux/sort.h>
 #include <linux/stop_machine.h>
+#include <linux/uaccess.h>
 #include <asm/sections.h>
 #include <asm/uaccess.h>
 #include <asm/unaligned.h>
@@ -550,7 +551,7 @@ static unsigned long read_pointer(const u8 **pLoc,
                return 0;
        }
        if ((ptrType & DW_EH_PE_indirect)
-           && __get_user(value, (unsigned long *)value))
+           && probe_kernel_address((unsigned long *)value, value))
                return 0;
        *pLoc = ptr.p8;
 
@@ -982,18 +983,19 @@ int unwind(struct unwind_frame_info *frame)
                        & (sizeof(unsigned long) - 1))) {
                        unsigned long link;
 
-                       if (!__get_user(link,
+                       if (!probe_kernel_address(
                                        (unsigned long *)(UNW_FP(frame)
-                                                         + FRAME_LINK_OFFSET))
+                                                         + FRAME_LINK_OFFSET),
+                                                 link)
 # if FRAME_RETADDR_OFFSET < 0
                           && link > bottom && link < UNW_FP(frame)
 # else
                           && link > UNW_FP(frame) && link < bottom
 # endif
                           && !(link & (sizeof(link) - 1))
-                          && !__get_user(UNW_PC(frame),
+                          && !probe_kernel_address(
                                          (unsigned long *)(UNW_FP(frame)
-                                                           + FRAME_RETADDR_OFFSET))) {
+                                                           + FRAME_RETADDR_OFFSET), UNW_PC(frame))) {
                                UNW_SP(frame) = UNW_FP(frame) + FRAME_RETADDR_OFFSET
 # if FRAME_RETADDR_OFFSET < 0
                                        -
@@ -1104,7 +1106,7 @@ int unwind(struct unwind_frame_info *frame)
                                        return -EIO;
                                switch(reg_info[i].width) {
 #define CASE(n)     case sizeof(u##n): \
-                                       __get_user(FRAME_REG(i, u##n), (u##n *)addr); \
+                                       probe_kernel_address((u##n *)addr, FRAME_REG(i, u##n)); \
                                        break
                                CASES;
 #undef CASE