powerpc: Fix vDSO clock_getres()

commit 552263456215ada7ee8700ce022d12b0cffe4802 upstream.

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")
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
[bwh: Backported to 3.16:
 - In asm-offsets.c, use DEFINE() instead of OFFSET()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index 1e0ee59c82768adbcc8181cb3ef0d399bb1496e4..6e700593fcb11adef7499fcc1585035e209995f5 100644 (file)
--- 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 213fcaf4168d056f3aec2492bc83a45d04b3e1be..eaafd1e4728bd30755ec2f905cee5aec75e21709 100644 (file)
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -397,6 +397,7 @@ int main(void)
        DEFINE(WTOM_CLOCK_NSEC, offsetof(struct vdso_data, wtom_clock_nsec));
        DEFINE(STAMP_XTIME, offsetof(struct vdso_data, stamp_xtime));
        DEFINE(STAMP_SEC_FRAC, offsetof(struct vdso_data, stamp_sec_fraction));
+       DEFINE(CLOCK_HRTIMER_RES, offsetof(struct vdso_data, hrtimer_res));
        DEFINE(CFG_ICACHE_BLOCKSZ, offsetof(struct vdso_data, icache_block_size));
        DEFINE(CFG_DCACHE_BLOCKSZ, offsetof(struct vdso_data, dcache_block_size));
        DEFINE(CFG_ICACHE_LOGBLOCKSZ, offsetof(struct vdso_data, icache_log_block_size));
@@ -425,7 +426,6 @@ int main(void)
        DEFINE(CLOCK_REALTIME, CLOCK_REALTIME);
        DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC);
        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 9fff9cdcc5196c3a20b9129d7e407c1dbc113cb7..1c1142f0bd4e4d81b6db58e8d5491eb61fbc4d39 100644 (file)
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -781,6 +781,7 @@ void update_vsyscall_old(struct timespec *wall_time, struct timespec *wtm,
        vdso_data->wtom_clock_nsec = wtm->tv_nsec;
        vdso_data->stamp_xtime = *wall_time;
        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 8bacb8721961fdd0ce9a63772c06ef10e0b9e0c7..aca0550077836c2678bcda3c9995409d13d5a1b2 100644 (file)
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -159,12 +159,15 @@ 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 6a6a8495bd55f139de8dda3cc142ebfeee247e64..f00ba94c3f9654ff0810d854e8b0da80507a1de2 100644 (file)
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -144,12 +144,15 @@ 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