diff options
Diffstat (limited to 'elf')
| -rw-r--r-- | elf/dl-load.c | 2 | ||||
| -rw-r--r-- | elf/dl-load.h | 3 | ||||
| -rw-r--r-- | elf/dl-map-segments.h | 50 |
3 files changed, 50 insertions, 5 deletions
diff --git a/elf/dl-load.c b/elf/dl-load.c index bf8957e73c..721593135e 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -1,5 +1,6 @@ /* Map in a shared object's segments from the file. Copyright (C) 1995-2021 Free Software Foundation, Inc. + Copyright The GNU Toolchain Authors. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -1150,6 +1151,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, c->mapend = ALIGN_UP (ph->p_vaddr + ph->p_filesz, GLRO(dl_pagesize)); c->dataend = ph->p_vaddr + ph->p_filesz; c->allocend = ph->p_vaddr + ph->p_memsz; + c->mapalign = ph->p_align; c->mapoff = ALIGN_DOWN (ph->p_offset, GLRO(dl_pagesize)); /* Determine whether there is a gap between the last segment diff --git a/elf/dl-load.h b/elf/dl-load.h index e329d49a81..e6dabcb336 100644 --- a/elf/dl-load.h +++ b/elf/dl-load.h @@ -1,5 +1,6 @@ /* Map in a shared object's segments from the file. Copyright (C) 1995-2021 Free Software Foundation, Inc. + Copyright The GNU Toolchain Authors. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -74,7 +75,7 @@ ELF_PREFERRED_ADDRESS_DATA; Its details have been expanded out and converted. */ struct loadcmd { - ElfW(Addr) mapstart, mapend, dataend, allocend; + ElfW(Addr) mapstart, mapend, dataend, allocend, mapalign; ElfW(Off) mapoff; int prot; /* PROT_* bits. */ }; diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h index f9fb110ee3..70a4c40695 100644 --- a/elf/dl-map-segments.h +++ b/elf/dl-map-segments.h @@ -1,5 +1,6 @@ /* Map in a shared object's segments. Generic version. Copyright (C) 1995-2021 Free Software Foundation, Inc. + Copyright The GNU Toolchain Authors. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -18,6 +19,50 @@ #include <dl-load.h> +/* Map a segment and align it properly. */ + +static __always_inline ElfW(Addr) +_dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref, + const size_t maplength, int fd) +{ + if (__glibc_likely (c->mapalign <= GLRO(dl_pagesize))) + return (ElfW(Addr)) __mmap ((void *) mappref, maplength, c->prot, + MAP_COPY|MAP_FILE, fd, c->mapoff); + + /* If the segment alignment > the page size, allocate enough space to + ensure that the segment can be properly aligned. */ + ElfW(Addr) maplen = (maplength >= c->mapalign + ? (maplength + c->mapalign) + : (2 * c->mapalign)); + ElfW(Addr) map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplen, + PROT_NONE, + MAP_ANONYMOUS|MAP_PRIVATE, + -1, 0); + if (__glibc_unlikely ((void *) map_start == MAP_FAILED)) + return map_start; + + ElfW(Addr) map_start_aligned = ALIGN_UP (map_start, c->mapalign); + map_start_aligned = (ElfW(Addr)) __mmap ((void *) map_start_aligned, + maplength, c->prot, + MAP_COPY|MAP_FILE|MAP_FIXED, + fd, c->mapoff); + if (__glibc_unlikely ((void *) map_start_aligned == MAP_FAILED)) + __munmap ((void *) map_start, maplen); + else + { + /* Unmap the unused regions. */ + ElfW(Addr) delta = map_start_aligned - map_start; + if (delta) + __munmap ((void *) map_start, delta); + ElfW(Addr) map_end = map_start_aligned + maplength; + delta = map_start + maplen - map_end; + if (delta) + __munmap ((void *) map_end, delta); + } + + return map_start_aligned; +} + /* This implementation assumes (as does the corresponding implementation of _dl_unmap_segments, in dl-unmap-segments.h) that shared objects are always laid out with all segments contiguous (or with gaps @@ -53,10 +98,7 @@ _dl_map_segments (struct link_map *l, int fd, - MAP_BASE_ADDR (l)); /* Remember which part of the address space this object uses. */ - l->l_map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplength, - c->prot, - MAP_COPY|MAP_FILE, - fd, c->mapoff); + l->l_map_start = _dl_map_segment (c, mappref, maplength, fd); if (__glibc_unlikely ((void *) l->l_map_start == MAP_FAILED)) return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT; |