perf kcore_copy: Calculate offset from phnum

In preparation to add more program headers, calculate offset from the
number of phdrs.

Signed-off-by: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: ahunter6

tools/perf/util/symbol-elf.c

@@ -1682,7 +1682,7 @@ int kcore_copy(const char *from_dir, const char *to_dir)
 	struct kcore kcore;
 	struct kcore extract;
 	int idx = 0, err = -1;
-	off_t offset = page_size, sz, modules_offset = 0;
+	off_t offset, sz, modules_offset = 0;
 	struct kcore_copy_info kci = { .stext = 0, };
 	char kcore_filename[PATH_MAX];
 	char extract_filename[PATH_MAX];
@@ -1710,6 +1710,10 @@ int kcore_copy(const char *from_dir, const char *to_dir)
 	if (kcore__copy_hdr(&kcore, &extract, kci.phnum))
 		goto out_extract_close;
 
+	offset = gelf_fsize(extract.elf, ELF_T_EHDR, 1, EV_CURRENT) +
+		 gelf_fsize(extract.elf, ELF_T_PHDR, kci.phnum, EV_CURRENT);
+	offset = round_up(offset, page_size);
+
 	if (kcore__add_phdr(&extract, idx++, offset, kci.kernel_map.addr,
 			    kci.kernel_map.len))
 		goto out_extract_close;