diff options
Diffstat (limited to 'backport-elf-Properly-align-PT_LOAD-segments-BZ-28676.patch')
| -rw-r--r-- | backport-elf-Properly-align-PT_LOAD-segments-BZ-28676.patch | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/backport-elf-Properly-align-PT_LOAD-segments-BZ-28676.patch b/backport-elf-Properly-align-PT_LOAD-segments-BZ-28676.patch new file mode 100644 index 0000000..365aeca --- /dev/null +++ b/backport-elf-Properly-align-PT_LOAD-segments-BZ-28676.patch @@ -0,0 +1,135 @@ +From 718fdd87b1b98ef88e883a37d9c18867256fa5a4 Mon Sep 17 00:00:00 2001 +From: Rongwei Wang <rongwei.wang@linux.alibaba.com> +Date: Fri, 10 Dec 2021 20:39:10 +0800 +Subject: [PATCH] elf: Properly align PT_LOAD segments [BZ #28676] + +When PT_LOAD segment alignment > the page size, allocate enough space to +ensure that the segment can be properly aligned. This change helps code +segments use huge pages become simple and available. + +This fixes [BZ #28676]. + +Signed-off-by: Xu Yu <xuyu@linux.alibaba.com> +Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com> +--- + elf/dl-load.c | 2 ++ + elf/dl-load.h | 3 ++- + 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; + +-- +2.43.0 + |