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Re: [PATCH 1/8] x86-64 memchr/wmemchr: Properly handle the length parameter [BZ# 24097]
On Thu, Jan 17, 2019 at 8:54 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On x32, the size_t parameter may be passed in the lower 32 bits of a
> 64-bit register with the non-zero upper 32 bits. The string/memory
> functions written in assembly can only use the lower 32 bits of a
> 64-bit register as length or must clear the upper 32 bits before using
> the full 64-bit register for length.
>
> This pach fixes memchr/wmemchr for x32. Tested on x86-64 and x32. On
> x86-64, libc.so is the same with and withou the fix.
>
> [BZ# 24097]
> * sysdeps/x86_64/memchr.S: Use RDX_LP for length. Clear the
> upper 32 bits of RDX register.
> * sysdeps/x86_64/multiarch/memchr-avx2.S: Likewise.
> * sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memchr and
> tst-size_t-wmemchr.
> * sysdeps/x86_64/x32/test-size_t.h: New file.
> * sysdeps/x86_64/x32/tst-size_t-memchr.c: Likewise.
> * sysdeps/x86_64/x32/tst-size_t-wmemchr.c: Likewise.
> diff --git a/sysdeps/x86_64/x32/test-size_t.h b/sysdeps/x86_64/x32/test-size_t.h
> new file mode 100644
> index 0000000000..fbef565bda
> --- /dev/null
> +++ b/sysdeps/x86_64/x32/test-size_t.h
> @@ -0,0 +1,170 @@
> +/* Test string/memory functions with size_t in the lower 32 bits of
> + 64-bit register.
> + Copyright (C) 2019 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <http://www.gnu.org/licenses/>. */
> +
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/mman.h>
> +#include <sys/param.h>
> +#include <unistd.h>
> +#include <fcntl.h>
> +#include <error.h>
> +#include <errno.h>
> +#include <time.h>
> +#include <ifunc-impl-list.h>
> +
> +/* On x32, parameter_t may be passed in a 64-bit register with the LEN
> + field in the lower 32 bits. When the LEN field of 64-bit register
> + is passed to string/memory function as the size_t parameter, only
> + the lower 32 bits can be used. */
> +typedef struct
> +{
> + union
> + {
> + size_t len;
> + void (*fn) (void);
> + };
> + void *p;
> +} parameter_t;
> +
> +typedef struct
> +{
> + const char *name;
> + void (*fn) (void);
> + long test;
> +} impl_t;
> +extern impl_t __start_impls[], __stop_impls[];
> +
> +#define IMPL(name, test) \
> + impl_t tst_ ## name \
> + __attribute__ ((section ("impls"), aligned (sizeof (void *)))) \
> + = { __STRING (name), (void (*) (void))name, test };
> +
> +#ifndef _GNU_SOURCE
> +#define _GNU_SOURCE
> +#endif
> +
> +#undef __USE_STRING_INLINES
> +
> +/* We are compiled under _ISOMAC, so libc-symbols.h does not do this
> + for us. */
> +#include "config.h"
> +#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
> +# define inhibit_loop_to_libcall \
> + __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
> +#else
> +# define inhibit_loop_to_libcall
> +#endif
> +
> +#define GL(x) _##x
> +#define GLRO(x) _##x
> +
> +unsigned char *buf1, *buf2;
> +size_t page_size;
> +
> +#define CALL(parm, ...) \
> + (* (proto_t) (parm).fn) (__VA_ARGS__)
> +
> +#ifdef TEST_NAME
> +/* Increase size of FUNC_LIST if assert is triggered at run-time. */
> +static struct libc_ifunc_impl func_list[32];
> +static int func_count;
> +static int impl_count = -1;
> +static impl_t *impl_array;
> +
> +# define FOR_EACH_IMPL(impl, notall) \
> + impl_t *impl; \
> + int count; \
> + if (impl_count == -1) \
> + { \
> + impl_count = 0; \
> + if (func_count != 0) \
> + { \
> + int f; \
> + impl_t *skip = NULL, *a; \
> + for (impl = __start_impls; impl < __stop_impls; ++impl) \
> + if (strcmp (impl->name, TEST_NAME) == 0) \
> + skip = impl; \
> + else \
> + impl_count++; \
> + a = impl_array = malloc ((impl_count + func_count) * \
> + sizeof (impl_t)); \
> + for (impl = __start_impls; impl < __stop_impls; ++impl) \
> + if (impl != skip) \
> + *a++ = *impl; \
> + for (f = 0; f < func_count; f++) \
> + if (func_list[f].usable) \
> + { \
> + a->name = func_list[f].name; \
> + a->fn = func_list[f].fn; \
> + a->test = 1; \
> + a++; \
> + } \
> + impl_count = a - impl_array; \
> + } \
> + else \
> + { \
> + impl_count = __stop_impls - __start_impls; \
> + impl_array = __start_impls; \
> + } \
> + } \
> + impl = impl_array; \
> + for (count = 0; count < impl_count; ++count, ++impl) \
> + if (!notall || impl->test)
> +#else
> +# define FOR_EACH_IMPL(impl, notall) \
> + for (impl_t *impl = __start_impls; impl < __stop_impls; ++impl) \
> + if (!notall || impl->test)
> +#endif
> +
> +#ifndef BUF1PAGES
> +# define BUF1PAGES 1
> +#endif
> +
> +static void
> +test_init (void)
> +{
> +#ifdef TEST_NAME
> + func_count = __libc_ifunc_impl_list (TEST_NAME, func_list,
> + (sizeof func_list
> + / sizeof func_list[0]));
> +#endif
> +
> + page_size = 2 * getpagesize ();
> +#ifdef MIN_PAGE_SIZE
> + if (page_size < MIN_PAGE_SIZE)
> + page_size = MIN_PAGE_SIZE;
> +#endif
> + buf1 = mmap (0, (BUF1PAGES + 1) * page_size, PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANON, -1, 0);
> + if (buf1 == MAP_FAILED)
> + error (EXIT_FAILURE, errno, "mmap failed");
> + if (mprotect (buf1 + BUF1PAGES * page_size, page_size, PROT_NONE))
> + error (EXIT_FAILURE, errno, "mprotect failed");
> + buf2 = mmap (0, 2 * page_size, PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANON, -1, 0);
> + if (buf2 == MAP_FAILED)
> + error (EXIT_FAILURE, errno, "mmap failed");
> + if (mprotect (buf2 + page_size, page_size, PROT_NONE))
> + error (EXIT_FAILURE, errno, "mprotect failed");
> +
> + memset (buf1, 0xa5, BUF1PAGES * page_size);
> + memset (buf2, 0x5a, page_size);
> +}
We can reuse <string/test-string.h>:
#define TEST_MAIN
#include <string/test-string.h>
/* On x32, parameter_t may be passed in a 64-bit register with the LEN
field in the lower 32 bits. When the LEN field of 64-bit register
is passed to string/memory function as the size_t parameter, only
the lower 32 bits can be used. */
typedef struct
{
union
{
size_t len;
void (*fn) (void);
};
void *p;
} parameter_t;
--
H.J.