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    Subject[PATCH v2 2/2] powerpc: use probe_user_read()
    Date
    Instead of opencoding, use probe_user_read() to failessly
    read a user location.

    Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
    ---
    v2: Using probe_user_read() instead of probe_user_address()

    arch/powerpc/kernel/process.c | 12 +-----------
    arch/powerpc/mm/fault.c | 6 +-----
    arch/powerpc/perf/callchain.c | 20 +++-----------------
    arch/powerpc/perf/core-book3s.c | 8 +-------
    arch/powerpc/sysdev/fsl_pci.c | 10 ++++------
    5 files changed, 10 insertions(+), 46 deletions(-)

    diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
    index ce393df243aa..6a4b59d574c2 100644
    --- a/arch/powerpc/kernel/process.c
    +++ b/arch/powerpc/kernel/process.c
    @@ -1298,16 +1298,6 @@ void show_user_instructions(struct pt_regs *regs)

    pc = regs->nip - (NR_INSN_TO_PRINT * 3 / 4 * sizeof(int));

    - /*
    - * Make sure the NIP points at userspace, not kernel text/data or
    - * elsewhere.
    - */
    - if (!__access_ok(pc, NR_INSN_TO_PRINT * sizeof(int), USER_DS)) {
    - pr_info("%s[%d]: Bad NIP, not dumping instructions.\n",
    - current->comm, current->pid);
    - return;
    - }
    -
    seq_buf_init(&s, buf, sizeof(buf));

    while (n) {
    @@ -1318,7 +1308,7 @@ void show_user_instructions(struct pt_regs *regs)
    for (i = 0; i < 8 && n; i++, n--, pc += sizeof(int)) {
    int instr;

    - if (probe_kernel_address((const void *)pc, instr)) {
    + if (probe_user_read(&instr, (void __user *)pc, sizeof(instr))) {
    seq_buf_printf(&s, "XXXXXXXX ");
    continue;
    }
    diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
    index 887f11bcf330..ec74305fa330 100644
    --- a/arch/powerpc/mm/fault.c
    +++ b/arch/powerpc/mm/fault.c
    @@ -276,12 +276,8 @@ static bool bad_stack_expansion(struct pt_regs *regs, unsigned long address,
    if ((flags & FAULT_FLAG_WRITE) && (flags & FAULT_FLAG_USER) &&
    access_ok(nip, sizeof(*nip))) {
    unsigned int inst;
    - int res;

    - pagefault_disable();
    - res = __get_user_inatomic(inst, nip);
    - pagefault_enable();
    - if (!res)
    + if (!probe_user_read(&inst, nip, sizeof(inst)))
    return !store_updates_sp(inst);
    *must_retry = true;
    }
    diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
    index 0af051a1974e..0680efb2237b 100644
    --- a/arch/powerpc/perf/callchain.c
    +++ b/arch/powerpc/perf/callchain.c
    @@ -159,12 +159,8 @@ static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
    ((unsigned long)ptr & 7))
    return -EFAULT;

    - pagefault_disable();
    - if (!__get_user_inatomic(*ret, ptr)) {
    - pagefault_enable();
    + if (!probe_user_read(ret, ptr, sizeof(*ret)))
    return 0;
    - }
    - pagefault_enable();

    return read_user_stack_slow(ptr, ret, 8);
    }
    @@ -175,12 +171,8 @@ static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
    ((unsigned long)ptr & 3))
    return -EFAULT;

    - pagefault_disable();
    - if (!__get_user_inatomic(*ret, ptr)) {
    - pagefault_enable();
    + if (!probe_user_read(ret, ptr, sizeof(*ret)))
    return 0;
    - }
    - pagefault_enable();

    return read_user_stack_slow(ptr, ret, 4);
    }
    @@ -307,17 +299,11 @@ static inline int current_is_64bit(void)
    */
    static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
    {
    - int rc;
    -
    if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
    ((unsigned long)ptr & 3))
    return -EFAULT;

    - pagefault_disable();
    - rc = __get_user_inatomic(*ret, ptr);
    - pagefault_enable();
    -
    - return rc;
    + return probe_user_read(ret, ptr, sizeof(*ret));
    }

    static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
    diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
    index b0723002a396..4b64ddf0db68 100644
    --- a/arch/powerpc/perf/core-book3s.c
    +++ b/arch/powerpc/perf/core-book3s.c
    @@ -416,7 +416,6 @@ static void power_pmu_sched_task(struct perf_event_context *ctx, bool sched_in)
    static __u64 power_pmu_bhrb_to(u64 addr)
    {
    unsigned int instr;
    - int ret;
    __u64 target;

    if (is_kernel_addr(addr)) {
    @@ -427,13 +426,8 @@ static __u64 power_pmu_bhrb_to(u64 addr)
    }

    /* Userspace: need copy instruction here then translate it */
    - pagefault_disable();
    - ret = __get_user_inatomic(instr, (unsigned int __user *)addr);
    - if (ret) {
    - pagefault_enable();
    + if (probe_user_read(&instr, (unsigned int __user *)addr, sizeof(instr)))
    return 0;
    - }
    - pagefault_enable();

    target = branch_target(&instr);
    if ((!target) || (instr & BRANCH_ABSOLUTE))
    diff --git a/arch/powerpc/sysdev/fsl_pci.c b/arch/powerpc/sysdev/fsl_pci.c
    index 918be816b097..c8a1b26489f5 100644
    --- a/arch/powerpc/sysdev/fsl_pci.c
    +++ b/arch/powerpc/sysdev/fsl_pci.c
    @@ -1068,13 +1068,11 @@ int fsl_pci_mcheck_exception(struct pt_regs *regs)
    addr += mfspr(SPRN_MCAR);

    if (is_in_pci_mem_space(addr)) {
    - if (user_mode(regs)) {
    - pagefault_disable();
    - ret = get_user(inst, (__u32 __user *)regs->nip);
    - pagefault_enable();
    - } else {
    + if (user_mode(regs))
    + ret = probe_user_read(&inst, (void __user *)regs->nip,
    + sizeof(inst));
    + else
    ret = probe_kernel_address((void *)regs->nip, inst);
    - }

    if (!ret && mcheck_handle_load(regs, inst)) {
    regs->nip += 4;
    --
    2.13.3
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