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Date: Thu, 26 Nov 2020 14:42:43 -0300 From: Arnaldo Carvalho de Melo <acme@...nel.org> To: Jiri Olsa <jolsa@...nel.org> Cc: lkml <linux-kernel@...r.kernel.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Ingo Molnar <mingo@...nel.org>, Mark Rutland <mark.rutland@....com>, Namhyung Kim <namhyung@...nel.org>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Michael Petlan <mpetlan@...hat.com>, Song Liu <songliubraving@...com>, Ian Rogers <irogers@...gle.com>, Stephane Eranian <eranian@...gle.com>, Alexey Budankov <alexey.budankov@...ux.intel.com>, Andi Kleen <ak@...ux.intel.com>, Adrian Hunter <adrian.hunter@...el.com> Subject: Re: [PATCH 05/25] tools lib: Adopt memchr_inv() from kernel Em Thu, Nov 26, 2020 at 06:00:06PM +0100, Jiri Olsa escreveu: > We'll use it to check for undefined/zero data. Thanks, applied. - Arnaldo > Signed-off-by: Jiri Olsa <jolsa@...nel.org> > --- > 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); > +} > -- > 2.26.2 > -- - Arnaldo
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