From 2c9af8421d2b4a7fcce163e7bc81a118d22fd346 Mon Sep 17 00:00:00 2001 From: Noah Goldstein Date: Wed, 8 Jun 2022 14:34:59 -0700 Subject: x86: Fix page cross case in rawmemchr-avx2 [BZ #29234] commit 6dcbb7d95dded20153b12d76d2f4e0ef0cda4f35 Author: Noah Goldstein Date: Mon Jun 6 21:11:33 2022 -0700 x86: Shrink code size of memchr-avx2.S Changed how the page cross case aligned string (rdi) in rawmemchr. This was incompatible with how `L(cross_page_continue)` expected the pointer to be aligned and would cause rawmemchr to read data start started before the beginning of the string. What it would read was in valid memory but could count CHAR matches resulting in an incorrect return value. This commit fixes that issue by essentially reverting the changes to the L(page_cross) case as they didn't really matter. Test cases added and all pass with the new code (and where confirmed to fail with the old code). Reviewed-by: H.J. Lu --- string/test-rawmemchr.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 56 insertions(+), 1 deletion(-) (limited to 'string') diff --git a/string/test-rawmemchr.c b/string/test-rawmemchr.c index cafb752..703e8ec 100644 --- a/string/test-rawmemchr.c +++ b/string/test-rawmemchr.c @@ -17,6 +17,7 @@ . */ #include +#include #define TEST_MAIN #define TEST_NAME "rawmemchr" @@ -51,12 +52,44 @@ do_one_test (impl_t *impl, const char *s, int c, char *exp_res) } static void +do_test_bz29234 (void) +{ + size_t i, j; + char *ptr_start; + char *buf = xmmap (0, 8192, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1); + + memset (buf, -1, 8192); + + ptr_start = buf + 4096 - 8; + + /* Out of range matches before the start of a page. */ + memset (ptr_start - 8, 0x1, 8); + + for (j = 0; j < 8; ++j) + { + for (i = 0; i < 128; ++i) + { + ptr_start[i + j] = 0x1; + + FOR_EACH_IMPL (impl, 0) + do_one_test (impl, (char *) (ptr_start + j), 0x1, + ptr_start + i + j); + + ptr_start[i + j] = 0xff; + } + } + + xmunmap (buf, 8192); +} + +static void do_test (size_t align, size_t pos, size_t len, int seek_char) { size_t i; char *result; - align &= 7; + align &= getpagesize () - 1; if (align + len >= page_size) return; @@ -114,6 +147,13 @@ do_random_tests (void) } } + if (align) + { + p[align - 1] = seek_char; + if (align > 4) + p[align - 4] = seek_char; + } + assert (pos < len); size_t r = random (); if ((r & 31) == 0) @@ -129,6 +169,13 @@ do_random_tests (void) result, p); ret = 1; } + + if (align) + { + p[align - 1] = seek_char; + if (align > 4) + p[align - 4] = seek_char; + } } } @@ -150,14 +197,22 @@ test_main (void) do_test (i, 64, 256, 23); do_test (0, 16 << i, 2048, 0); do_test (i, 64, 256, 0); + + do_test (getpagesize () - i, 64, 256, 23); + do_test (getpagesize () - i, 64, 256, 0); } for (i = 1; i < 32; ++i) { do_test (0, i, i + 1, 23); do_test (0, i, i + 1, 0); + + do_test (getpagesize () - 7, i, i + 1, 23); + do_test (getpagesize () - i / 2, i, i + 1, 23); + do_test (getpagesize () - i, i, i + 1, 23); } do_random_tests (); + do_test_bz29234 (); return ret; } -- cgit v1.1