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powerpc: Fix vDSO clock_getres()

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clock_getres in the vDSO library has to preserve the same behaviour
of posix_get_hrtimer_res().

In particular, posix_get_hrtimer_res() does:
    sec = 0;
    ns = hrtimer_resolution;
and hrtimer_resolution depends on the enablement of the high
resolution timers that can happen either at compile or at run time.

Fix the powerpc vdso implementation of clock_getres keeping a copy of
hrtimer_resolution in vdso data and using that directly.

Fixes: a7f290dad3 ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel")
Cc: stable@vger.kernel.org
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
[chleroy: changed CLOCK_REALTIME_RES to CLOCK_HRTIMER_RES]
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a55eca3a5e85233838c2349783bcb5164dae1d09.1575273217.git.christophe.leroy@c-s.fr
This commit is contained in:
Vincenzo Frascino 2019-12-02 07:57:29 +00:00 committed by Michael Ellerman
parent 6f4679b956
commit 5522634562
5 changed files with 14 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/include/asm/vdso_datapage.h
View File

@ -83,6 +83,7 @@ struct vdso_data {
__s64 wtom_clock_sec; /* Wall to monotonic clock sec */
__s64 stamp_xtime_sec; /* xtime secs as at tb_orig_stamp */
__s64 stamp_xtime_nsec; /* xtime nsecs as at tb_orig_stamp */
__u32 hrtimer_res; /* hrtimer resolution */
__u32 syscall_map_64[SYSCALL_MAP_SIZE]; /* map of syscalls */
__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
};
@ -105,6 +106,7 @@ struct vdso_data {
__s32 stamp_xtime_sec; /* xtime seconds as at tb_orig_stamp */
__s32 stamp_xtime_nsec; /* xtime nsecs as at tb_orig_stamp */
__u32 stamp_sec_fraction; /* fractional seconds of stamp_xtime */
__u32 hrtimer_res; /* hrtimer resolution */
__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
__u32 dcache_block_size; /* L1 d-cache block size */
__u32 icache_block_size; /* L1 i-cache block size */

2
arch/powerpc/kernel/asm-offsets.c
View File

@ -388,6 +388,7 @@ int main(void)
OFFSET(STAMP_XTIME_SEC, vdso_data, stamp_xtime_sec);
OFFSET(STAMP_XTIME_NSEC, vdso_data, stamp_xtime_nsec);
OFFSET(STAMP_SEC_FRAC, vdso_data, stamp_sec_fraction);
OFFSET(CLOCK_HRTIMER_RES, vdso_data, hrtimer_res);
OFFSET(CFG_ICACHE_BLOCKSZ, vdso_data, icache_block_size);
OFFSET(CFG_DCACHE_BLOCKSZ, vdso_data, dcache_block_size);
OFFSET(CFG_ICACHE_LOGBLOCKSZ, vdso_data, icache_log_block_size);
@ -413,7 +414,6 @@ int main(void)
DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE);
DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE);
DEFINE(NSEC_PER_SEC, NSEC_PER_SEC);
DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC);
#ifdef CONFIG_BUG
DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));

1
arch/powerpc/kernel/time.c
View File

@ -960,6 +960,7 @@ void update_vsyscall(struct timekeeper *tk)
vdso_data->stamp_xtime_sec = xt.tv_sec;
vdso_data->stamp_xtime_nsec = xt.tv_nsec;
vdso_data->stamp_sec_fraction = frac_sec;
vdso_data->hrtimer_res = hrtimer_resolution;
smp_wmb();
++(vdso_data->tb_update_count);
}

7
arch/powerpc/kernel/vdso32/gettimeofday.S
View File

@ -154,12 +154,15 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
cror cr0*4+eq,cr0*4+eq,cr1*4+eq
bne cr0,99f
mflr r12
.cfi_register lr,r12
bl __get_datapage@local /* get data page */
lwz r5, CLOCK_HRTIMER_RES(r3)
mtlr r12
li r3,0
cmpli cr0,r4,0
crclr cr0*4+so
beqlr
lis r5,CLOCK_REALTIME_RES@h
ori r5,r5,CLOCK_REALTIME_RES@l
stw r3,TSPC32_TV_SEC(r4)
stw r5,TSPC32_TV_NSEC(r4)
blr

7
arch/powerpc/kernel/vdso64/gettimeofday.S
View File

@ -186,12 +186,15 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
cror cr0*4+eq,cr0*4+eq,cr1*4+eq
bne cr0,99f
mflr r12
.cfi_register lr,r12
bl V_LOCAL_FUNC(__get_datapage)
lwz r5, CLOCK_HRTIMER_RES(r3)
mtlr r12
li r3,0
cmpldi cr0,r4,0
crclr cr0*4+so
beqlr
lis r5,CLOCK_REALTIME_RES@h
ori r5,r5,CLOCK_REALTIME_RES@l
std r3,TSPC64_TV_SEC(r4)
std r5,TSPC64_TV_NSEC(r4)
blr