aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/nacl/dl-map-segments.h
diff options
context:
space:
mode:
Diffstat (limited to 'sysdeps/nacl/dl-map-segments.h')
-rw-r--r--sysdeps/nacl/dl-map-segments.h238
1 files changed, 238 insertions, 0 deletions
diff --git a/sysdeps/nacl/dl-map-segments.h b/sysdeps/nacl/dl-map-segments.h
new file mode 100644
index 0000000000..f305da304a
--- /dev/null
+++ b/sysdeps/nacl/dl-map-segments.h
@@ -0,0 +1,238 @@
+/* Map in a shared object's segments. NaCl version.
+ Copyright (C) 2015 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 <assert.h>
+#include <dl-load.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <libc-internal.h>
+
+
+/* This is basically pread, but with iteration after short reads. */
+static bool
+read_in_data (int fd, void *data, size_t len, off_t pos)
+{
+ if (__glibc_unlikely (__lseek (fd, pos, SEEK_SET) == (off_t) -1))
+ return true;
+ while (len > 0)
+ {
+ ssize_t n = __read (fd, data, len);
+ if (__glibc_unlikely (n < 0))
+ return true;
+ if (__glibc_unlikely (n == 0))
+ {
+ errno = EFTYPE;
+ return true;
+ }
+ data += n;
+ len -= n;
+ }
+ return false;
+}
+
+static const char *
+_dl_map_segments (struct link_map *l, int fd,
+ const ElfW(Ehdr) *header, int type,
+ const struct loadcmd loadcmds[], size_t nloadcmds,
+ const size_t maplength, bool has_holes,
+ struct link_map *loader)
+{
+ if (__builtin_expect (type, ET_DYN) == ET_DYN)
+ {
+ /* This is a position-independent shared object. Let the system
+ choose where to place it.
+
+ As a refinement, sometimes we have an address that we would
+ prefer to map such objects at; but this is only a preference,
+ the OS can do whatever it likes. */
+ ElfW(Addr) mappref
+ = (ELF_PREFERRED_ADDRESS (loader, maplength,
+ loadcmds[0].mapstart & GLRO(dl_use_load_bias))
+ - MAP_BASE_ADDR (l));
+
+ uintptr_t mapstart;
+ if (__glibc_likely (loadcmds[0].prot & PROT_EXEC))
+ {
+ /* When there is a code segment, we must use the
+ allocate_code_data interface to choose a location. */
+
+ uintptr_t code_size = loadcmds[0].allocend - loadcmds[0].mapstart;
+ uintptr_t data_offset;
+ size_t data_size;
+
+ if (__glibc_likely (nloadcmds > 1))
+ {
+ data_offset = loadcmds[1].mapstart - loadcmds[0].mapstart;
+ data_size = ALIGN_UP (maplength - data_offset,
+ GLRO(dl_pagesize));
+ }
+ else
+ {
+ data_offset = 0;
+ data_size = 0;
+ }
+
+ int error = __nacl_irt_code_data_alloc.allocate_code_data
+ (mappref, code_size, data_offset, data_size, &mapstart);
+ if (__glibc_unlikely (error))
+ {
+ errno = error;
+ return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;
+ }
+ }
+ else
+ {
+ /* With no code pages involved, plain mmap works fine. */
+ void *mapped = __mmap ((void *) mappref, maplength,
+ PROT_NONE, MAP_ANON, -1, 0);
+ if (__glibc_unlikely (mapped == MAP_FAILED))
+ return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;
+ mapstart = (uintptr_t) mapped;
+ }
+
+ l->l_addr = mapstart - loadcmds[0].mapstart;
+ }
+
+ /* Remember which part of the address space this object uses. */
+ l->l_map_start = loadcmds[0].mapstart + l->l_addr;
+ l->l_map_end = l->l_map_start + maplength;
+ l->l_contiguous = !has_holes;
+
+ /* Now actually map (or read) in each segment. */
+ for (const struct loadcmd *c = loadcmds; c < &loadcmds[nloadcmds]; ++c)
+ if (__glibc_likely (c->mapend > c->mapstart))
+ {
+ /* Unlike POSIX mmap, NaCl's mmap does not reliably handle COW
+ faults in the remainder of the final partial page. So to get
+ the expected behavior for the unaligned boundary between data
+ and bss, it's necessary to allocate the final partial page of
+ data as anonymous memory rather than mapping it from the file. */
+
+ size_t maplen = c->mapend - c->mapstart;
+ if (c->mapend > c->dataend && c->allocend > c->dataend)
+ maplen = (c->dataend & -GLRO(dl_pagesize)) - c->mapstart;
+
+ /* Map the segment contents from the file. */
+ if (__glibc_unlikely (__mmap ((void *) (l->l_addr + c->mapstart),
+ maplen, c->prot,
+ MAP_FIXED|MAP_COPY|MAP_FILE,
+ fd, c->mapoff)
+ == MAP_FAILED))
+ {
+ switch (errno)
+ {
+ case EINVAL:
+ case ENOTSUP:
+ case ENOSYS:
+ break;
+ default:
+ return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;
+ }
+
+ /* No mmap support for this file. */
+ if (c->prot & PROT_EXEC)
+ {
+ /* Read the data into a temporary buffer. */
+ const size_t len = c->mapend - c->mapstart;
+ void *data = __mmap (NULL, len, PROT_READ | PROT_WRITE,
+ MAP_ANON|MAP_PRIVATE, -1, 0);
+ if (__glibc_unlikely (data == MAP_FAILED))
+ return DL_MAP_SEGMENTS_ERROR_MAP_ZERO_FILL;
+ if (read_in_data (fd, data, len, c->mapoff))
+ return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;
+ /* Now validate and install the code. */
+ int error = __nacl_irt_dyncode.dyncode_create
+ ((void *) (l->l_addr + c->mapstart), data, len);
+ __munmap (data, len);
+ if (__glibc_unlikely (error))
+ {
+ errno = error;
+ return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;
+ }
+ }
+ else
+ {
+ /* Allocate the pages. */
+ if (__mmap ((void *) (l->l_addr + c->mapstart),
+ c->mapend - c->mapstart, c->prot | PROT_WRITE,
+ MAP_FIXED|MAP_ANON|MAP_PRIVATE, -1, 0)
+ == MAP_FAILED)
+ return DL_MAP_SEGMENTS_ERROR_MAP_ZERO_FILL;
+ /* Now read in the data. */
+ if (read_in_data (fd, (void *) (l->l_addr + c->mapstart),
+ c->dataend - c->mapstart, c->mapoff))
+ return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;
+ /* Now that we've filled the pages, reset the page
+ protections to what they should be. */
+ if (!(c->prot & PROT_WRITE)
+ && __mprotect ((void *) (l->l_addr + c->mapstart),
+ c->mapend - c->mapstart, c->prot) < 0)
+ return DL_MAP_SEGMENTS_ERROR_MPROTECT;
+ }
+ }
+ else if (c->allocend > c->dataend)
+ {
+ /* Extra zero pages should appear at the end of this segment,
+ after the data mapped from the file. */
+
+ uintptr_t allocend = c->mapend;
+ if (c->mapend > c->dataend)
+ {
+ /* The final data page was partial. So we didn't map it in.
+ Instead, we must allocate an anonymous page to fill. */
+ if (c->prot & PROT_WRITE)
+ /* Do the whole allocation right here. */
+ allocend = c->allocend;
+ if (__mmap ((void *) (l->l_addr + c->mapstart + maplen),
+ allocend - (c->mapstart + maplen), c->prot,
+ MAP_FIXED|MAP_ANON|MAP_PRIVATE, -1, 0)
+ == MAP_FAILED)
+ return DL_MAP_SEGMENTS_ERROR_MAP_ZERO_FILL;
+ if (read_in_data (fd,
+ (void *) (l->l_addr + c->mapstart + maplen),
+ c->dataend & (GLRO(dl_pagesize) - 1),
+ c->mapoff + maplen))
+ return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;
+ /* Now that we've filled the page, reset its
+ protections to what they should be. */
+ if (!(c->prot & PROT_WRITE)
+ && __mprotect ((void *) (l->l_addr + c->mapstart + maplen),
+ c->mapend - (c->mapstart + maplen),
+ c->prot) < 0)
+ return DL_MAP_SEGMENTS_ERROR_MPROTECT;
+ }
+
+ /* Now allocate the pure zero-fill pages. */
+ if (allocend < c->allocend
+ && (__mmap ((void *) (l->l_addr + c->mapstart + allocend),
+ c->allocend - (c->mapstart + allocend), c->prot,
+ MAP_FIXED|MAP_ANON|MAP_PRIVATE, -1, 0)
+ == MAP_FAILED))
+ return DL_MAP_SEGMENTS_ERROR_MAP_ZERO_FILL;
+ }
+
+ _dl_postprocess_loadcmd (l, header, c);
+ }
+
+ /* Notify ELF_PREFERRED_ADDRESS that we have to load this one
+ fixed. */
+ ELF_FIXED_ADDRESS (loader, c->mapstart);
+
+ return NULL;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-29 06:34:44 +0000