[PATCH v4 1/3] powerpc: Fix vDSO clock_getres()

Vincenzo Frascino
2019-05-23T11:21:14Z

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: a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support
to 32 bits kernel")
Cc: stable@vger.kernel.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
---

Note: This patch is independent from the others in this series, hence it
can be merged singularly by the powerpc maintainers.

arch/powerpc/include/asm/vdso_datapage.h | 2 ++
arch/powerpc/kernel/asm-offsets.c | 2 +-
arch/powerpc/kernel/time.c | 1 +
arch/powerpc/kernel/vdso32/gettimeofday.S | 7 +++++--
arch/powerpc/kernel/vdso64/gettimeofday.S | 7 +++++--
5 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index bbc06bd72b1f..4333b9a473dc 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -86,6 +86,7 @@ struct vdso_data {
__s32 wtom_clock_nsec; /* Wall to monotonic clock nsec */
__s64 wtom_clock_sec; /* Wall to monotonic clock sec */
struct timespec stamp_xtime; /* xtime 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 */
};
@@ -107,6 +108,7 @@ struct vdso_data {
__s32 wtom_clock_nsec;
struct timespec stamp_xtime; /* xtime 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 */
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 8e02444e9d3d..dfc40f29f2b9 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -389,6 +389,7 @@ int main(void)
OFFSET(WTOM_CLOCK_NSEC, vdso_data, wtom_clock_nsec);
OFFSET(STAMP_XTIME, vdso_data, stamp_xtime);
OFFSET(STAMP_SEC_FRAC, vdso_data, stamp_sec_fraction);
+ OFFSET(CLOCK_REALTIME_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);
@@ -419,7 +420,6 @@ 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));
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 325d60633dfa..4ea4e9d7a58e 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -963,6 +963,7 @@ void update_vsyscall(struct timekeeper *tk)
vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
vdso_data->stamp_xtime = xt;
vdso_data->stamp_sec_fraction = frac_sec;
+ vdso_data->hrtimer_res = hrtimer_resolution;
smp_wmb();
++(vdso_data->tb_update_count);
}
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index afd516b572f8..2b5f9e83c610 100644
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -160,12 +160,15 @@ 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
+ lwz r5,CLOCK_REALTIME_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
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index 1f324c28705b..f07730f73d5e 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -190,12 +190,15 @@ 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_REALTIME_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
--
2.21.0