diff options
authorNathan Lynch <nathan_lynch@mentor.com>2014-02-05 05:53:04 +0000
committerMark Brown <broonie@linaro.org>2014-05-14 12:18:35 +0100
commit1a94c46eed86275ee899eae5210dd14d4129a03a (patch)
parent3a44eb49a2734233b5fc9d98afee53be701f4c4d (diff)
arm64: vdso: fix coarse clock handling
commit 069b918623e1510e58dacf178905a72c3baa3ae4 upstream. When __kernel_clock_gettime is called with a CLOCK_MONOTONIC_COARSE or CLOCK_REALTIME_COARSE clock id, it returns incorrectly to whatever the caller has placed in x2 ("ret x2" to return from the fast path). Fix this by saving x30/LR to x2 only in code that will call __do_get_tspec, restoring x30 afterward, and using a plain "ret" to return from the routine. Also: while the resulting tv_nsec value for CLOCK_REALTIME and CLOCK_MONOTONIC must be computed using intermediate values that are left-shifted by cs_shift (x12, set by __do_get_tspec), the results for coarse clocks should be calculated using unshifted values (xtime_coarse_nsec is in units of actual nanoseconds). The current code shifts intermediate values by x12 unconditionally, but x12 is uninitialized when servicing a coarse clock. Fix this by setting x12 to 0 once we know we are dealing with a coarse clock id. Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit fb569d15d867a06e89b1be8278404b6fbf6b5bde) Signed-off-by: Mark Brown <broonie@linaro.org>
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
index f0a6d10b5211..fe652ffd34c2 100644
--- a/arch/arm64/kernel/vdso/gettimeofday.S
+++ b/arch/arm64/kernel/vdso/gettimeofday.S
@@ -103,6 +103,8 @@ ENTRY(__kernel_clock_gettime)
bl __do_get_tspec
seqcnt_check w9, 1b
+ mov x30, x2
b.ne 6f
@@ -118,6 +120,9 @@ ENTRY(__kernel_clock_gettime)
ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne
b.ne 8f
+ /* xtime_coarse_nsec is already right-shifted */
+ mov x12, #0
/* Get coarse timespec. */
adr vdso_data, _vdso_data
3: seqcnt_acquire
@@ -156,7 +161,7 @@ ENTRY(__kernel_clock_gettime)
lsr x11, x11, x12
stp x10, x11, [x1, #TSPEC_TV_SEC]
mov x0, xzr
- ret x2
+ ret
mov x30, x2
8: /* Syscall fallback. */