[POWERPC] Fix VDSO gettimeofday() when called with NULL struct timeval

Consider the prototype for gettimeofday():
	int gettimofday(struct timeval *tv, struct timezone *tz);

Although it is valid to call with /either/ tv or tz being NULL, and
the C version of sys_gettimeofday() supports this, the current version
of gettimeofday() in the VDSO will SEGV if called with a NULL tv.

This adds a check for tv being NULL so that it doesn't SEGV.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index 40ffd9b6cef7..2d7a5104c666 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -1,5 +1,4 @@
-
-        /*
+/*
  * Userland implementation of gettimeofday() for 64 bits processes in a
  * ppc64 kernel for use in the vDSO
  *
@@ -32,6 +31,8 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday)
         mr      r11,r3                  /* r11 holds tv */
         mr      r10,r4                  /* r10 holds tz */
         bl      V_LOCAL_FUNC(__get_datapage)    /* get data page */
+        cmpldi  r10,0                   /* check if tv is NULL */
+        beq     2f
         bl      V_LOCAL_FUNC(__do_get_xsec)     /* get xsec from tb & kernel */
         lis     r7,15                   /* r7 = 1000000 = USEC_PER_SEC */
         ori     r7,r7,16960
@@ -43,8 +44,8 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday)
                                          * XSEC_PER_SEC
                                          */
         rldicl  r0,r0,44,20
-        cmpldi  cr0,r10,0               /* check if tz is NULL */
         std     r0,TVAL64_TV_USEC(r11)  /* store usec in tv */
+2:      cmpldi  r10,0                   /* check if tz is NULL */
         beq     1f
         lwz     r4,CFG_TZ_MINUTEWEST(r3)/* fill tz */
         lwz     r5,CFG_TZ_DSTTIME(r3)