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    Subject[PATCH 5.4 163/177] powerpc: Fix vDSO clock_getres()
    Date
    From: Vincenzo Frascino <vincenzo.frascino@arm.com>

    [ Upstream commit 552263456215ada7ee8700ce022d12b0cffe4802 ]

    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
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 c61d59ed3b45f..2ccb938d85447 100644
    --- a/arch/powerpc/include/asm/vdso_datapage.h
    +++ b/arch/powerpc/include/asm/vdso_datapage.h
    @@ -82,6 +82,7 @@ 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 */
    };
    @@ -103,6 +104,7 @@ 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 484f54dab2475..5c0a1e17219b7 100644
    --- a/arch/powerpc/kernel/asm-offsets.c
    +++ b/arch/powerpc/kernel/asm-offsets.c
    @@ -387,6 +387,7 @@ 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_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);
    @@ -417,7 +418,6 @@ 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 694522308cd51..619447b1b7971 100644
    --- a/arch/powerpc/kernel/time.c
    +++ b/arch/powerpc/kernel/time.c
    @@ -959,6 +959,7 @@ 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 becd9f8767ede..a967e795b96d9 100644
    --- a/arch/powerpc/kernel/vdso32/gettimeofday.S
    +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
    @@ -156,12 +156,15 @@ 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 07bfe33fe8745..81757f06bbd7a 100644
    --- 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
    --
    2.20.1


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