powerpc: Fix vDSO clock_getres()

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
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

diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index a115970a68090146329f2d4cde8e15c77f5bfe46..40f13f3626d3c1bebc5f1ef808d87cb84b4d7c91 100644 (file)
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -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     */

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index f22bd6d1fe9331331715c37b11f0d302a4fae266..3d47aec7becf12dc7def0789e67399f5d9baa917 100644 (file)
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -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));

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 2d13cea13954eb799282d607da356b456151c712..1168e8b37e30696de1408ad816bae50d1d8c4693 100644 (file)
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -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);
 }

diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index c8e6902cb01b1bc28143fb46232e73b51261f109..3306672f57a9eb9f6a78aa43fd029bdfde0904d3 100644 (file)
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -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

diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index 1f24e411af80102df223ae0add899ce5a68893d8..1c9a04703250449aea9a4a5cd3f89cdebad26ccc 100644 (file)
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -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