diff options
author | Al Viro <viro@zeniv.linux.org.uk> | 2020-03-08 09:16:37 -0400 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2021-03-08 10:21:11 -0500 |
commit | d0f1088b31db2d03497a74ca67755df5515f8ff4 (patch) | |
tree | 8252b8cb97ae2041ea26a72490dd94466a936758 /fs | |
parent | a38fd8748464831584a19438cbb3082b5a2dab15 (diff) | |
download | linux-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')
-rw-r--r-- | fs/binfmt_elf.c | 4 | ||||
-rw-r--r-- | fs/binfmt_elf_fdpic.c | 3 | ||||
-rw-r--r-- | fs/coredump.c | 72 |
3 files changed, 45 insertions, 34 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index b12ba98ae9f5..187b3f2b9202 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -2267,8 +2267,7 @@ static int elf_core_dump(struct coredump_params *cprm) goto end_coredump; /* Align to page */ - if (!dump_skip(cprm, dataoff - cprm->pos)) - goto end_coredump; + dump_skip_to(cprm, dataoff); for (i = 0; i < vma_count; i++) { struct core_vma_metadata *meta = vma_meta + i; @@ -2276,7 +2275,6 @@ static int elf_core_dump(struct coredump_params *cprm) if (!dump_user_range(cprm, meta->start, meta->dump_size)) goto end_coredump; } - dump_truncate(cprm); if (!elf_core_write_extra_data(cprm)) goto end_coredump; diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 3cfd6cd46f26..2c99b102c860 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -1631,8 +1631,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm) goto end_coredump; } - if (!dump_skip(cprm, dataoff - cprm->pos)) - goto end_coredump; + dump_skip_to(cprm, dataoff); if (!elf_fdpic_dump_segments(cprm, vma_meta, vma_count)) goto end_coredump; 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 |