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authorAl Viro <viro@zeniv.linux.org.uk>2020-03-08 09:16:37 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2021-03-08 10:21:11 -0500
commitd0f1088b31db2d03497a74ca67755df5515f8ff4 (patch)
tree8252b8cb97ae2041ea26a72490dd94466a936758 /fs/coredump.c
parenta38fd8748464831584a19438cbb3082b5a2dab15 (diff)
downloadlinux-d0f1088b31db2d03497a74ca67755df5515f8ff4.tar.bz2
coredump: don't bother with do_truncate()
have dump_skip() just remember how much needs to be skipped, leave actual seeks/writing zeroes to the next dump_emit() or the end of coredump output, whichever comes first. And instead of playing with do_truncate() in the end, just write one NUL at the end of the last gap (if any). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/coredump.c')
-rw-r--r--fs/coredump.c72
1 files changed, 43 insertions, 29 deletions
diff --git a/fs/coredump.c b/fs/coredump.c
index 1c0fdc1aa70b..2868e3e171ae 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -809,6 +809,16 @@ void do_coredump(const kernel_siginfo_t *siginfo)
}
file_start_write(cprm.file);
core_dumped = binfmt->core_dump(&cprm);
+ /*
+ * Ensures that file size is big enough to contain the current
+ * file postion. This prevents gdb from complaining about
+ * a truncated file if the last "write" to the file was
+ * dump_skip.
+ */
+ if (cprm.to_skip) {
+ cprm.to_skip--;
+ dump_emit(&cprm, "", 1);
+ }
file_end_write(cprm.file);
}
if (ispipe && core_pipe_limit)
@@ -835,7 +845,7 @@ fail:
* do on a core-file: use only these functions to write out all the
* necessary info.
*/
-int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
+static int __dump_emit(struct coredump_params *cprm, const void *addr, int nr)
{
struct file *file = cprm->file;
loff_t pos = file->f_pos;
@@ -855,9 +865,8 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
return 1;
}
-EXPORT_SYMBOL(dump_emit);
-int dump_skip(struct coredump_params *cprm, size_t nr)
+static int __dump_skip(struct coredump_params *cprm, size_t nr)
{
static char zeroes[PAGE_SIZE];
struct file *file = cprm->file;
@@ -869,13 +878,35 @@ int dump_skip(struct coredump_params *cprm, size_t nr)
return 1;
} else {
while (nr > PAGE_SIZE) {
- if (!dump_emit(cprm, zeroes, PAGE_SIZE))
+ if (!__dump_emit(cprm, zeroes, PAGE_SIZE))
return 0;
nr -= PAGE_SIZE;
}
- return dump_emit(cprm, zeroes, nr);
+ return __dump_emit(cprm, zeroes, nr);
}
}
+
+int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
+{
+ if (cprm->to_skip) {
+ if (!__dump_skip(cprm, cprm->to_skip))
+ return 0;
+ cprm->to_skip = 0;
+ }
+ return __dump_emit(cprm, addr, nr);
+}
+EXPORT_SYMBOL(dump_emit);
+
+void dump_skip_to(struct coredump_params *cprm, unsigned long pos)
+{
+ cprm->to_skip = pos - cprm->pos;
+}
+EXPORT_SYMBOL(dump_skip_to);
+
+void dump_skip(struct coredump_params *cprm, size_t nr)
+{
+ cprm->to_skip += nr;
+}
EXPORT_SYMBOL(dump_skip);
#ifdef CONFIG_ELF_CORE
@@ -902,11 +933,11 @@ int dump_user_range(struct coredump_params *cprm, unsigned long start,
stop = !dump_emit(cprm, kaddr, PAGE_SIZE);
kunmap_local(kaddr);
put_page(page);
+ if (stop)
+ return 0;
} else {
- stop = !dump_skip(cprm, PAGE_SIZE);
+ dump_skip(cprm, PAGE_SIZE);
}
- if (stop)
- return 0;
}
return 1;
}
@@ -914,33 +945,16 @@ int dump_user_range(struct coredump_params *cprm, unsigned long start,
int dump_align(struct coredump_params *cprm, int align)
{
- unsigned mod = cprm->pos & (align - 1);
+ unsigned mod = (cprm->pos + cprm->to_skip) & (align - 1);
if (align & (align - 1))
return 0;
- return mod ? dump_skip(cprm, align - mod) : 1;
+ if (mod)
+ cprm->to_skip += align - mod;
+ return 1;
}
EXPORT_SYMBOL(dump_align);
/*
- * Ensures that file size is big enough to contain the current file
- * postion. This prevents gdb from complaining about a truncated file
- * if the last "write" to the file was dump_skip.
- */
-void dump_truncate(struct coredump_params *cprm)
-{
- struct file *file = cprm->file;
- loff_t offset;
-
- if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
- offset = file->f_op->llseek(file, 0, SEEK_CUR);
- if (i_size_read(file->f_mapping->host) < offset)
- do_truncate(file_mnt_user_ns(file), file->f_path.dentry,
- offset, 0, file);
- }
-}
-EXPORT_SYMBOL(dump_truncate);
-
-/*
* The purpose of always_dump_vma() is to make sure that special kernel mappings
* that are useful for post-mortem analysis are included in every core dump.
* In that way we ensure that the core dump is fully interpretable later