From 16a583079e937f6f5e6274ef7fda6dbf7dcb669f Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 8 May 2020 08:42:12 -0700 Subject: pstore/ftrace: Provide ftrace log merging routine Move the ftrace log merging logic out of pstore/ram into pstore/ftrace so other backends can use it, like pstore/zone. Link: https://lore.kernel.org/lkml/20200510202436.63222-7-keescook@chromium.org/ Signed-off-by: Kees Cook --- fs/pstore/ftrace.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) (limited to 'fs/pstore/ftrace.c') diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c index bfbfc2698070..5c0450701293 100644 --- a/fs/pstore/ftrace.c +++ b/fs/pstore/ftrace.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include "internal.h" @@ -132,3 +133,56 @@ void pstore_unregister_ftrace(void) debugfs_remove_recursive(pstore_ftrace_dir); } + +ssize_t pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size, + const char *src_log, size_t src_log_size) +{ + 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_log_size % record_size; + dest_size = *dest_log_size - dest_off; + + src_off = src_log_size % record_size; + src_size = src_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_log + dest_off); + srec = (struct pstore_ftrace_record *)(src_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_log); + *dest_log = merged_buf; + *dest_log_size = total; + + return 0; +} +EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log); -- cgit v1.2.3-59-g8ed1b