Commit d0f1088b authored by Al Viro's avatar Al Viro
Browse files

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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent a38fd874

arch/powerpc/platforms/cell/spufs/coredump.c

+1 −2
Original line number Diff line number Diff line
@@ -149,8 +149,7 @@ static int spufs_arch_write_note(struct spu_context *ctx, int i, 
			return -EIO;

	}



	if (!dump_skip(cprm, roundup(cprm->pos - ret + sz, 4) - cprm->pos))

		return -EIO;

	dump_skip_to(cprm, roundup(cprm->pos - ret + sz, 4));

	return 0;

}

fs/binfmt_elf.c

+1 −3
Original line number Diff line number Diff line
@@ -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;

fs/binfmt_elf_fdpic.c

+1 −2
Original line number Diff line number Diff line
@@ -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;

fs/coredump.c

+43 −29
Original line number Diff line number Diff line
@@ -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 @@ void do_coredump(const kernel_siginfo_t *siginfo) 
 * 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;
@@ -869,12 +878,34 @@ 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);
@@ -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);

		} else {

			stop = !dump_skip(cprm, PAGE_SIZE);

		}

			if (stop)

				return 0;

		} else {

			dump_skip(cprm, PAGE_SIZE);

		}

	}

	return 1;

}
@@ -914,32 +945,15 @@ 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.

include/linux/binfmts.h

+1 −0
Original line number Diff line number Diff line
@@ -86,6 +86,7 @@ struct coredump_params { 
	unsigned long mm_flags;

	loff_t written;

	loff_t pos;

	loff_t to_skip;

};



/*