scripts/kallsyms: filter symbols not in kernel address space

This patch uses CONFIG_PAGE_OFFSET to filter symbols which
are not in kernel address space because these symbols are
generally for generating code purpose and can't be run at
kernel mode, so we needn't keep them in /proc/kallsyms.

For example, on ARM there are some symbols which may be
linked in relocatable code section, then perf can't parse
symbols any more from /proc/kallsyms, this patch fixes the
problem (introduced b9b32bf70f2fb710b07c94e13afbc729afe221da)

Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@vger.kernel.org

1 files changed, 11 insertions, 1 deletions

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 487ac6f37ca2..9a11f9f799f4 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -55,6 +55,7 @@ static struct sym_entry *table;
 static unsigned int table_size, table_cnt;
 static int all_symbols = 0;
 static char symbol_prefix_char = '\0';
+static unsigned long long kernel_start_addr = 0;
 
 int token_profit[0x10000];
 
@@ -65,7 +66,10 @@ unsigned char best_table_len[256];
 
 static void usage(void)
 {
-        fprintf(stderr, "Usage: kallsyms [--all-symbols] [--symbol-prefix=<prefix char>] < in.map > out.S\n");
+        fprintf(stderr, "Usage: kallsyms [--all-symbols] "
+                        "[--symbol-prefix=<prefix char>] "
+                        "[--page-offset=<CONFIG_PAGE_OFFSET>] "
+                        "< in.map > out.S\n");
         exit(1);
 }
 
@@ -194,6 +198,9 @@ static int symbol_valid(struct sym_entry *s)
         int i;
         int offset = 1;
 
+        if (s->addr < kernel_start_addr)
+                return 0;
+
         /* skip prefix char */
         if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char)
                 offset++;
@@ -646,6 +653,9 @@ int main(int argc, char **argv)
                                 if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
                                         p++;
                                 symbol_prefix_char = *p;
+                        } else if (strncmp(argv[i], "--page-offset=", 14) == 0) {
+                                const char *p = &argv[i][14];
+                                kernel_start_addr = strtoull(p, NULL, 16);
                         } else
                                 usage();
                 }