diff options
| -rw-r--r-- | elf/Makefile | 7 | ||||
| -rw-r--r-- | elf/dl-minimal-malloc.c | 112 | ||||
| -rw-r--r-- | elf/dl-minimal.c | 122 | ||||
| -rw-r--r-- | elf/dl-tunables.c | 7 | ||||
| -rw-r--r-- | sysdeps/generic/dl-minimal-malloc.h | 28 |
5 files changed, 157 insertions, 119 deletions
diff --git a/elf/Makefile b/elf/Makefile index 41c19668c3..72004484db 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -36,7 +36,7 @@ dl-routines = $(addprefix dl-,load lookup object reloc deps \ exception sort-maps lookup-direct \ call-libc-early-init write \ thread_gscope_wait tls_init_tp \ - debug-symbols) + debug-symbols minimal-malloc) ifeq (yes,$(use-ldconfig)) dl-routines += dl-cache endif @@ -75,6 +75,11 @@ CFLAGS-dl-runtime.c += -fexceptions -fasynchronous-unwind-tables CFLAGS-dl-lookup.c += -fexceptions -fasynchronous-unwind-tables CFLAGS-dl-iteratephdr.c += $(uses-callbacks) +# Called during static library initialization, so turn stack-protection +# off for non-shared builds. +CFLAGS-dl-minimal-malloc.o = $(no-stack-protector) +CFLAGS-dl-minimal-malloc.op = $(no-stack-protector) + # On targets without __builtin_memset, rtld.c uses a hand-coded loop # in _dl_start. Make sure this isn't turned into a call to regular memset. ifeq (yes,$(have-loop-to-function)) diff --git a/elf/dl-minimal-malloc.c b/elf/dl-minimal-malloc.c new file mode 100644 index 0000000000..939b5271ca --- /dev/null +++ b/elf/dl-minimal-malloc.c @@ -0,0 +1,112 @@ +/* Minimal malloc implementation for dynamic linker and static + initialization. + Copyright (C) 1995-2021 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 + <https://www.gnu.org/licenses/>. */ + +#include <assert.h> +#include <string.h> +#include <ldsodefs.h> +#include <malloc/malloc-internal.h> + +static void *alloc_ptr, *alloc_end, *alloc_last_block; + +/* Allocate an aligned memory block. */ +void * +__minimal_malloc (size_t n) +{ + if (alloc_end == 0) + { + /* Consume any unused space in the last page of our data segment. */ + extern int _end attribute_hidden; + alloc_ptr = &_end; + alloc_end = (void *) 0 + (((alloc_ptr - (void *) 0) + + GLRO(dl_pagesize) - 1) + & ~(GLRO(dl_pagesize) - 1)); + } + + /* Make sure the allocation pointer is ideally aligned. */ + alloc_ptr = (void *) 0 + (((alloc_ptr - (void *) 0) + MALLOC_ALIGNMENT - 1) + & ~(MALLOC_ALIGNMENT - 1)); + + if (alloc_ptr + n >= alloc_end || n >= -(uintptr_t) alloc_ptr) + { + /* Insufficient space left; allocate another page plus one extra + page to reduce number of mmap calls. */ + caddr_t page; + size_t nup = (n + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1); + if (__glibc_unlikely (nup == 0 && n != 0)) + return NULL; + nup += GLRO(dl_pagesize); + page = __mmap (0, nup, PROT_READ|PROT_WRITE, + MAP_ANON|MAP_PRIVATE, -1, 0); + if (page == MAP_FAILED) + return NULL; + if (page != alloc_end) + alloc_ptr = page; + alloc_end = page + nup; + } + + alloc_last_block = (void *) alloc_ptr; + alloc_ptr += n; + return alloc_last_block; +} + +/* We use this function occasionally since the real implementation may + be optimized when it can assume the memory it returns already is + set to NUL. */ +void * +__minimal_calloc (size_t nmemb, size_t size) +{ + /* New memory from the trivial malloc above is always already cleared. + (We make sure that's true in the rare occasion it might not be, + by clearing memory in free, below.) */ + size_t bytes = nmemb * size; + +#define HALF_SIZE_T (((size_t) 1) << (8 * sizeof (size_t) / 2)) + if (__builtin_expect ((nmemb | size) >= HALF_SIZE_T, 0) + && size != 0 && bytes / size != nmemb) + return NULL; + + return malloc (bytes); +} + +/* This will rarely be called. */ +void +__minimal_free (void *ptr) +{ + /* We can free only the last block allocated. */ + if (ptr == alloc_last_block) + { + /* Since this is rare, we clear the freed block here + so that calloc can presume malloc returns cleared memory. */ + memset (alloc_last_block, '\0', alloc_ptr - alloc_last_block); + alloc_ptr = alloc_last_block; + } +} + +/* This is only called with the most recent block returned by malloc. */ +void * +__minimal_realloc (void *ptr, size_t n) +{ + if (ptr == NULL) + return malloc (n); + assert (ptr == alloc_last_block); + size_t old_size = alloc_ptr - alloc_last_block; + alloc_ptr = alloc_last_block; + void *new = malloc (n); + return new != ptr ? memcpy (new, ptr, old_size) : new; +} diff --git a/elf/dl-minimal.c b/elf/dl-minimal.c index 4e7f11aeab..152192d451 100644 --- a/elf/dl-minimal.c +++ b/elf/dl-minimal.c @@ -16,23 +16,14 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ -#include <errno.h> -#include <limits.h> -#include <stdio.h> -#include <string.h> -#include <tls.h> -#include <unistd.h> -#include <sys/mman.h> -#include <sys/param.h> -#include <sys/types.h> +#include <assert.h> #include <ldsodefs.h> #include <dl-irel.h> #include <dl-hash.h> #include <dl-sym-post.h> #include <_itoa.h> -#include <malloc/malloc-internal.h> +#include <dl-minimal-malloc.h> -#include <assert.h> /* The rtld startup code calls __rtld_malloc_init_stubs after the first self-relocation to adjust the pointers to the minimal @@ -44,19 +35,13 @@ __typeof (free) *__rtld_free attribute_relro; __typeof (malloc) *__rtld_malloc attribute_relro; __typeof (realloc) *__rtld_realloc attribute_relro; -/* Defined below. */ -static __typeof (calloc) rtld_calloc; -static __typeof (free) rtld_free; -static __typeof (malloc) rtld_malloc; -static __typeof (realloc) rtld_realloc; - void __rtld_malloc_init_stubs (void) { - __rtld_calloc = &rtld_calloc; - __rtld_free = &rtld_free; - __rtld_malloc = &rtld_malloc; - __rtld_realloc = &rtld_realloc; + __rtld_calloc = &__minimal_calloc; + __rtld_free = &__minimal_free; + __rtld_malloc = &__minimal_malloc; + __rtld_realloc = &__minimal_realloc; } bool @@ -64,7 +49,7 @@ __rtld_malloc_is_complete (void) { /* The caller assumes that there is an active malloc. */ assert (__rtld_malloc != NULL); - return __rtld_malloc != &rtld_malloc; + return __rtld_malloc != &__minimal_malloc; } /* Lookup NAME at VERSION in the scope of MATCH. */ @@ -115,99 +100,6 @@ __rtld_malloc_init_real (struct link_map *main_map) __rtld_realloc = new_realloc; } -/* Minimal malloc allocator for used during initial link. After the - initial link, a full malloc implementation is interposed, either - the one in libc, or a different one supplied by the user through - interposition. */ - -static void *alloc_ptr, *alloc_end, *alloc_last_block; - -/* Allocate an aligned memory block. */ -static void * -rtld_malloc (size_t n) -{ - if (alloc_end == 0) - { - /* Consume any unused space in the last page of our data segment. */ - extern int _end attribute_hidden; - alloc_ptr = &_end; - alloc_end = (void *) 0 + (((alloc_ptr - (void *) 0) - + GLRO(dl_pagesize) - 1) - & ~(GLRO(dl_pagesize) - 1)); - } - - /* Make sure the allocation pointer is ideally aligned. */ - alloc_ptr = (void *) 0 + (((alloc_ptr - (void *) 0) + MALLOC_ALIGNMENT - 1) - & ~(MALLOC_ALIGNMENT - 1)); - - if (alloc_ptr + n >= alloc_end || n >= -(uintptr_t) alloc_ptr) - { - /* Insufficient space left; allocate another page plus one extra - page to reduce number of mmap calls. */ - caddr_t page; - size_t nup = (n + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1); - if (__glibc_unlikely (nup == 0 && n != 0)) - return NULL; - nup += GLRO(dl_pagesize); - page = __mmap (0, nup, PROT_READ|PROT_WRITE, - MAP_ANON|MAP_PRIVATE, -1, 0); - if (page == MAP_FAILED) - return NULL; - if (page != alloc_end) - alloc_ptr = page; - alloc_end = page + nup; - } - - alloc_last_block = (void *) alloc_ptr; - alloc_ptr += n; - return alloc_last_block; -} - -/* We use this function occasionally since the real implementation may - be optimized when it can assume the memory it returns already is - set to NUL. */ -static void * -rtld_calloc (size_t nmemb, size_t size) -{ - /* New memory from the trivial malloc above is always already cleared. - (We make sure that's true in the rare occasion it might not be, - by clearing memory in free, below.) */ - size_t bytes = nmemb * size; - -#define HALF_SIZE_T (((size_t) 1) << (8 * sizeof (size_t) / 2)) - if (__builtin_expect ((nmemb | size) >= HALF_SIZE_T, 0) - && size != 0 && bytes / size != nmemb) - return NULL; - - return malloc (bytes); -} - -/* This will rarely be called. */ -void -rtld_free (void *ptr) -{ - /* We can free only the last block allocated. */ - if (ptr == alloc_last_block) - { - /* Since this is rare, we clear the freed block here - so that calloc can presume malloc returns cleared memory. */ - memset (alloc_last_block, '\0', alloc_ptr - alloc_last_block); - alloc_ptr = alloc_last_block; - } -} - -/* This is only called with the most recent block returned by malloc. */ -void * -rtld_realloc (void *ptr, size_t n) -{ - if (ptr == NULL) - return malloc (n); - assert (ptr == alloc_last_block); - size_t old_size = alloc_ptr - alloc_last_block; - alloc_ptr = alloc_last_block; - void *new = malloc (n); - return new != ptr ? memcpy (new, ptr, old_size) : new; -} /* Avoid signal frobnication in setjmp/longjmp. Keeps things smaller. */ diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c index 1666736bc1..497e948f1c 100644 --- a/elf/dl-tunables.c +++ b/elf/dl-tunables.c @@ -31,6 +31,7 @@ #include <fcntl.h> #include <ldsodefs.h> #include <array_length.h> +#include <dl-minimal-malloc.h> #define TUNABLES_INTERNAL 1 #include "dl-tunables.h" @@ -48,13 +49,13 @@ tunables_strdup (const char *in) size_t i = 0; while (in[i++] != '\0'); - char *out = __sbrk (i); + char *out = __minimal_malloc (i + 1); /* For most of the tunables code, we ignore user errors. However, this is a system error - and running out of memory at program startup should be reported, so we do. */ - if (out == (void *)-1) - _dl_fatal_printf ("sbrk() failure while processing tunables\n"); + if (out == NULL) + _dl_fatal_printf ("failed to allocate memory to process tunables\n"); while (i-- > 0) out[i] = in[i]; diff --git a/sysdeps/generic/dl-minimal-malloc.h b/sysdeps/generic/dl-minimal-malloc.h new file mode 100644 index 0000000000..7f50e52df5 --- /dev/null +++ b/sysdeps/generic/dl-minimal-malloc.h @@ -0,0 +1,28 @@ +/* Minimal malloc implementation for dynamic linker and static + initialization. + Copyright (C) 2021 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 + <https://www.gnu.org/licenses/>. */ + +#ifndef _DL_MINIMAL_MALLOC_H +#define _DL_MINIMAL_MALLOC_H + +extern void *__minimal_malloc (size_t n) attribute_hidden; +extern void *__minimal_calloc (size_t nmemb, size_t size) attribute_hidden; +extern void __minimal_free (void *ptr) attribute_hidden; +extern void *__minimal_realloc (void *ptr, size_t n) attribute_hidden; + +#endif |