From: Jiri Olsa jolsa@kernel.org
stable inclusion from stable-5.10.69 commit 87c4144450e6f09afeb2adc336f35b5f5274205c bugzilla: 182675 https://gitee.com/openeuler/kernel/issues/I4I3ED
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit b3e453272d436aab8adbe810c6d7043670281487 upstream.
We'll use it to check for undefined/zero data.
Signed-off-by: Jiri Olsa jolsa@kernel.org Suggested-by: Arnaldo Carvalho de Melo acme@redhat.com Acked-by: Namhyung Kim namhyung@kernel.org Cc: Adrian Hunter adrian.hunter@intel.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Alexey Budankov alexey.budankov@linux.intel.com Cc: Andi Kleen ak@linux.intel.com Cc: Ian Rogers irogers@google.com Cc: Mark Rutland mark.rutland@arm.com Cc: Michael Petlan mpetlan@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Song Liu songliubraving@fb.com Cc: Stephane Eranian eranian@google.com Link: http://lore.kernel.org/lkml/20201126170026.2619053-6-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Chen Jun chenjun102@huawei.com Acked-by: Weilong Chen chenweilong@huawei.com
Signed-off-by: Chen Jun chenjun102@huawei.com --- tools/include/linux/string.h | 1 + tools/lib/string.c | 58 ++++++++++++++++++++++++++++++++++++ 2 files changed, 59 insertions(+)
diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h index 5e9e781905ed..db5c99318c79 100644 --- a/tools/include/linux/string.h +++ b/tools/include/linux/string.h @@ -46,4 +46,5 @@ extern char * __must_check skip_spaces(const char *);
extern char *strim(char *);
+extern void *memchr_inv(const void *start, int c, size_t bytes); #endif /* _TOOLS_LINUX_STRING_H_ */ diff --git a/tools/lib/string.c b/tools/lib/string.c index f645343815de..8b6892f959ab 100644 --- a/tools/lib/string.c +++ b/tools/lib/string.c @@ -168,3 +168,61 @@ char *strreplace(char *s, char old, char new) *s = new; return s; } + +static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) +{ + while (bytes) { + if (*start != value) + return (void *)start; + start++; + bytes--; + } + return NULL; +} + +/** + * memchr_inv - Find an unmatching character in an area of memory. + * @start: The memory area + * @c: Find a character other than c + * @bytes: The size of the area. + * + * returns the address of the first character other than @c, or %NULL + * if the whole buffer contains just @c. + */ +void *memchr_inv(const void *start, int c, size_t bytes) +{ + u8 value = c; + u64 value64; + unsigned int words, prefix; + + if (bytes <= 16) + return check_bytes8(start, value, bytes); + + value64 = value; + value64 |= value64 << 8; + value64 |= value64 << 16; + value64 |= value64 << 32; + + prefix = (unsigned long)start % 8; + if (prefix) { + u8 *r; + + prefix = 8 - prefix; + r = check_bytes8(start, value, prefix); + if (r) + return r; + start += prefix; + bytes -= prefix; + } + + words = bytes / 8; + + while (words) { + if (*(u64 *)start != value64) + return check_bytes8(start, value, 8); + start += 8; + words--; + } + + return check_bytes8(start, value, bytes % 8); +}