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Commit 2fbea82b authored by Joel Fernandes's avatar Joel Fernandes Committed by Kees Cook
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pstore: Merge per-CPU ftrace records into one 



Up until this patch, each of the per CPU ftrace buffers appear as a
separate ftrace-ramoops-N file. In this patch we merge all the zones into
one and populate a single ftrace-ramoops-0 file.

Signed-off-by: default avatarJoel Fernandes <joelaf@google.com>
[kees: clarified variables names, added -ENOMEM handling]
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent fbccdeb8

fs/pstore/ram.c

+109 −13
Original line number Diff line number Diff line
@@ -182,16 +182,69 @@ static bool prz_ok(struct persistent_ram_zone *prz) 
			   persistent_ram_ecc_string(prz, NULL, 0));

}



static ssize_t ftrace_log_combine(struct persistent_ram_zone *dest,

				  struct persistent_ram_zone *src)

{

	size_t dest_size, src_size, total, dest_off, src_off;

	size_t dest_idx = 0, src_idx = 0, merged_idx = 0;

	void *merged_buf;

	struct pstore_ftrace_record *drec, *srec, *mrec;

	size_t record_size = sizeof(struct pstore_ftrace_record);



	dest_off = dest->old_log_size % record_size;

	dest_size = dest->old_log_size - dest_off;



	src_off = src->old_log_size % record_size;

	src_size = src->old_log_size - src_off;



	total = dest_size + src_size;

	merged_buf = kmalloc(total, GFP_KERNEL);

	if (!merged_buf)

		return -ENOMEM;



	drec = (struct pstore_ftrace_record *)(dest->old_log + dest_off);

	srec = (struct pstore_ftrace_record *)(src->old_log + src_off);

	mrec = (struct pstore_ftrace_record *)(merged_buf);



	while (dest_size > 0 && src_size > 0) {

		if (pstore_ftrace_read_timestamp(&drec[dest_idx]) <

		    pstore_ftrace_read_timestamp(&srec[src_idx])) {

			mrec[merged_idx++] = drec[dest_idx++];

			dest_size -= record_size;

		} else {

			mrec[merged_idx++] = srec[src_idx++];

			src_size -= record_size;

		}

	}



	while (dest_size > 0) {

		mrec[merged_idx++] = drec[dest_idx++];

		dest_size -= record_size;

	}



	while (src_size > 0) {

		mrec[merged_idx++] = srec[src_idx++];

		src_size -= record_size;

	}



	kfree(dest->old_log);

	dest->old_log = merged_buf;

	dest->old_log_size = total;



	return 0;

}



static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,

				   int *count, struct timespec *time,

				   char **buf, bool *compressed,

				   ssize_t *ecc_notice_size,

				   struct pstore_info *psi)

{

	ssize_t size;

	ssize_t size = 0;

	struct ramoops_context *cxt = psi->data;

	struct persistent_ram_zone *prz = NULL;

	int header_length = 0;

	bool free_prz = false;



	/* Ramoops headers provide time stamps for PSTORE_TYPE_DMESG, but

	 * PSTORE_TYPE_CONSOLE and PSTORE_TYPE_FTRACE don't currently have
@@ -221,22 +274,56 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, 
	if (!prz_ok(prz))

		prz = ramoops_get_next_prz(&cxt->cprz, &cxt->console_read_cnt,

					   1, id, type, PSTORE_TYPE_CONSOLE, 0);



	if (!prz_ok(prz))

		prz = ramoops_get_next_prz(&cxt->mprz, &cxt->pmsg_read_cnt,

					   1, id, type, PSTORE_TYPE_PMSG, 0);



	/* ftrace is last since it may want to dynamically allocate memory. */

	if (!prz_ok(prz)) {

		while (cxt->ftrace_read_cnt < cxt->max_ftrace_cnt && !prz) {

		if (!(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)) {

			prz = ramoops_get_next_prz(cxt->fprzs,

					&cxt->ftrace_read_cnt,

					cxt->max_ftrace_cnt, id, type,

					&cxt->ftrace_read_cnt, 1, id, type,

					PSTORE_TYPE_FTRACE, 0);

			if (!prz_ok(prz))

		} else {

			/*

			 * Build a new dummy record which combines all the

			 * per-cpu records including metadata and ecc info.

			 */

			struct persistent_ram_zone *tmp_prz, *prz_next;



			tmp_prz = kzalloc(sizeof(struct persistent_ram_zone),

					  GFP_KERNEL);

			if (!tmp_prz)

				return -ENOMEM;

			free_prz = true;



			while (cxt->ftrace_read_cnt < cxt->max_ftrace_cnt) {

				prz_next = ramoops_get_next_prz(cxt->fprzs,

						&cxt->ftrace_read_cnt,

						cxt->max_ftrace_cnt, id,

						type, PSTORE_TYPE_FTRACE, 0);



				if (!prz_ok(prz_next))

					continue;



				tmp_prz->ecc_info = prz_next->ecc_info;

				tmp_prz->corrected_bytes +=

						prz_next->corrected_bytes;

				tmp_prz->bad_blocks += prz_next->bad_blocks;

				size = ftrace_log_combine(tmp_prz, prz_next);

				if (size)

					goto out;

			}

			*id = 0;

			prz = tmp_prz;

		}

	}



	if (!prz_ok(prz))

		prz = ramoops_get_next_prz(&cxt->mprz, &cxt->pmsg_read_cnt,

					   1, id, type, PSTORE_TYPE_PMSG, 0);

	if (!prz_ok(prz))

		return 0;

	if (!prz_ok(prz)) {

		size = 0;

		goto out;

	}



	size = persistent_ram_old_size(prz) - header_length;
@@ -244,12 +331,21 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, 
	*ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);



	*buf = kmalloc(size + *ecc_notice_size + 1, GFP_KERNEL);

	if (*buf == NULL)

		return -ENOMEM;

	if (*buf == NULL) {

		size = -ENOMEM;

		goto out;

	}



	memcpy(*buf, (char *)persistent_ram_old(prz) + header_length, size);



	persistent_ram_ecc_string(prz, *buf + size, *ecc_notice_size + 1);



out:

	if (free_prz) {

		kfree(prz->old_log);

		kfree(prz);

	}



	return size;

}