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| author | Nathan Lynch <nathan_lynch@mentor.com> | 2014-02-05 05:53:04 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-20 11:10:08 -0800 |
| commit | d8cec633b0488655ac324684d4cf53e312bcdf41 (patch) | |
| tree | 15790ce71ea61d3bfb23447429e7e0c1ab5244b7 | |
| parent | 3c9ddefba1c252df894a0157f792b87d54e17190 (diff) | |
| download | lwn-d8cec633b0488655ac324684d4cf53e312bcdf41.tar.gz lwn-d8cec633b0488655ac324684d4cf53e312bcdf41.zip | |
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>
| -rw-r--r-- | arch/arm64/kernel/vdso/gettimeofday.S | 7 |
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 + cmp w0, #CLOCK_MONOTONIC 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 7: mov x30, x2 8: /* Syscall fallback. */ |