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    Subject[PATCH 12/38] perf: Factor __output_copy to be usable with specific copy function
    Date
    From: Frederic Weisbecker <fweisbec@gmail.com>

    Adding a generic way to use __output_copy function with specific copy
    function via DEFINE_PERF_OUTPUT_COPY macro.

    Using this to add new __output_copy_user function, that provides output
    copy from user pointers. For x86 the copy_from_user_nmi function is used
    and __copy_from_user_inatomic for the rest of the architectures.

    This new function will be used in user stack dump on sample, coming in
    next patches.

    Signed-off-by: Jiri Olsa <jolsa@redhat.com>
    Cc: "Frank Ch. Eigler" <fche@redhat.com>
    Cc: Arun Sharma <asharma@fb.com>
    Cc: Benjamin Redelings <benjamin.redelings@nescent.org>
    Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
    Cc: Cyrill Gorcunov <gorcunov@openvz.org>
    Cc: Frank Ch. Eigler <fche@redhat.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Robert Richter <robert.richter@amd.com>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Tom Zanussi <tzanussi@gmail.com>
    Cc: Ulrich Drepper <drepper@gmail.com>
    Link: http://lkml.kernel.org/r/1344345647-11536-4-git-send-email-jolsa@redhat.com
    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    arch/x86/include/asm/perf_event.h | 2 +
    include/linux/perf_event.h | 2 +-
    kernel/events/internal.h | 62 ++++++++++++++++++++++++------------
    kernel/events/ring_buffer.c | 4 +-
    4 files changed, 46 insertions(+), 24 deletions(-)

    diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
    index cb4e43b..4fabcdf 100644
    --- a/arch/x86/include/asm/perf_event.h
    +++ b/arch/x86/include/asm/perf_event.h
    @@ -262,4 +262,6 @@ static inline void perf_check_microcode(void) { }
    static inline void amd_pmu_disable_virt(void) { }
    #endif

    +#define arch_perf_out_copy_user copy_from_user_nmi
    +
    #endif /* _ASM_X86_PERF_EVENT_H */
    diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
    index 3d4d847..d41394a 100644
    --- a/include/linux/perf_event.h
    +++ b/include/linux/perf_event.h
    @@ -1319,7 +1319,7 @@ static inline bool has_branch_stack(struct perf_event *event)
    extern int perf_output_begin(struct perf_output_handle *handle,
    struct perf_event *event, unsigned int size);
    extern void perf_output_end(struct perf_output_handle *handle);
    -extern void perf_output_copy(struct perf_output_handle *handle,
    +extern unsigned int perf_output_copy(struct perf_output_handle *handle,
    const void *buf, unsigned int len);
    extern int perf_swevent_get_recursion_context(void);
    extern void perf_swevent_put_recursion_context(int rctx);
    diff --git a/kernel/events/internal.h b/kernel/events/internal.h
    index a096c19..7fd5408 100644
    --- a/kernel/events/internal.h
    +++ b/kernel/events/internal.h
    @@ -2,6 +2,7 @@
    #define _KERNEL_EVENTS_INTERNAL_H

    #include <linux/hardirq.h>
    +#include <linux/uaccess.h>

    /* Buffer handling */

    @@ -76,30 +77,49 @@ static inline unsigned long perf_data_size(struct ring_buffer *rb)
    return rb->nr_pages << (PAGE_SHIFT + page_order(rb));
    }

    -static inline void
    -__output_copy(struct perf_output_handle *handle,
    - const void *buf, unsigned int len)
    +#define DEFINE_OUTPUT_COPY(func_name, memcpy_func) \
    +static inline unsigned int \
    +func_name(struct perf_output_handle *handle, \
    + const void *buf, unsigned int len) \
    +{ \
    + unsigned long size, written; \
    + \
    + do { \
    + size = min_t(unsigned long, handle->size, len); \
    + \
    + written = memcpy_func(handle->addr, buf, size); \
    + \
    + len -= written; \
    + handle->addr += written; \
    + buf += written; \
    + handle->size -= written; \
    + if (!handle->size) { \
    + struct ring_buffer *rb = handle->rb; \
    + \
    + handle->page++; \
    + handle->page &= rb->nr_pages - 1; \
    + handle->addr = rb->data_pages[handle->page]; \
    + handle->size = PAGE_SIZE << page_order(rb); \
    + } \
    + } while (len && written == size); \
    + \
    + return len; \
    +}
    +
    +static inline int memcpy_common(void *dst, const void *src, size_t n)
    {
    - do {
    - unsigned long size = min_t(unsigned long, handle->size, len);
    -
    - memcpy(handle->addr, buf, size);
    -
    - len -= size;
    - handle->addr += size;
    - buf += size;
    - handle->size -= size;
    - if (!handle->size) {
    - struct ring_buffer *rb = handle->rb;
    -
    - handle->page++;
    - handle->page &= rb->nr_pages - 1;
    - handle->addr = rb->data_pages[handle->page];
    - handle->size = PAGE_SIZE << page_order(rb);
    - }
    - } while (len);
    + memcpy(dst, src, n);
    + return n;
    }

    +DEFINE_OUTPUT_COPY(__output_copy, memcpy_common)
    +
    +#ifndef arch_perf_out_copy_user
    +#define arch_perf_out_copy_user __copy_from_user_inatomic
    +#endif
    +
    +DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user)
    +
    /* Callchain handling */
    extern struct perf_callchain_entry *
    perf_callchain(struct perf_event *event, struct pt_regs *regs);
    diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
    index 6ddaba4..b4c2ad3 100644
    --- a/kernel/events/ring_buffer.c
    +++ b/kernel/events/ring_buffer.c
    @@ -182,10 +182,10 @@ out:
    return -ENOSPC;
    }

    -void perf_output_copy(struct perf_output_handle *handle,
    +unsigned int perf_output_copy(struct perf_output_handle *handle,
    const void *buf, unsigned int len)
    {
    - __output_copy(handle, buf, len);
    + return __output_copy(handle, buf, len);
    }

    void perf_output_end(struct perf_output_handle *handle)
    --
    1.7.1


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