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Subject[PATCH 05/23] perf: Factor __output_copy to be usable with specific copy function
Date
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_nochk
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,
comming in next patches.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@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 588f52e..7b46815 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -257,4 +257,6 @@ static inline void perf_events_lapic_init(void) { }
static inline void amd_pmu_disable_virt(void) { }
#endif

+#define arch_perf_out_copy_user copy_from_user_nmi_nochk
+
#endif /* _ASM_X86_PERF_EVENT_H */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 969ee0b..cd40669 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1301,7 +1301,7 @@ 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 b0b107f..2206a0f 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 pt_regs *regs);
extern int get_callchain_buffers(void);
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)
--
1.7.7.6


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