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authorPaulo Marques <pmarques@grupopie.com>2008-02-06 04:37:33 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-06 13:41:07 -0500
commitf2df3f65d0b4337cfb5b19eab3ee28b177427c49 (patch)
tree86d8aae1e9ef8c57721c886f67a915ba1897dc69 /scripts/kallsyms.c
parenta6752f3f538e9dc0d0e7fdb2080532554a5eb395 (diff)
kallsyms should prefer non weak symbols
When resolving symbol names from addresses with aliased symbol names, kallsyms_lookup always returns the first symbol, even if it is a weak symbol. This patch changes this by sorting the symbols with the weak symbols last before feeding them to the kernel. This way the kernel runtime isn't changed at all, only the kallsyms build system is changed. Another side effect is that the symbols get sorted by address, too. So, even if future binutils version have some bug in "nm" that makes it fail to correctly sort symbols by address, the kernel won't be affected by this. Mathieu says: I created a module in LTTng that uses kallsyms to get the symbol corresponding to a specific system call address. Unfortunately, all the unimplemented syscalls were all referring to the (same) weak symbol identifying an unrelated system call rather that sys_ni (or whatever non-weak symbol would be expected). Kallsyms was dumbly returning the first symbol that matched. This patch makes sure kallsyms returns the non-weak symbol when there is one, which seems to be the expected result. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Looks-great-to: Rusty Russell <rusty@rustcorp.com.au> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'scripts/kallsyms.c')
-rw-r--r--scripts/kallsyms.c37
1 files changed, 34 insertions, 3 deletions
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 8fb87003d5d3..c912137f80e2 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -31,14 +31,13 @@
31 31
32#define KSYM_NAME_LEN 128 32#define KSYM_NAME_LEN 128
33 33
34
35struct sym_entry { 34struct sym_entry {
36 unsigned long long addr; 35 unsigned long long addr;
37 unsigned int len; 36 unsigned int len;
37 unsigned int start_pos;
38 unsigned char *sym; 38 unsigned char *sym;
39}; 39};
40 40
41
42static struct sym_entry *table; 41static struct sym_entry *table;
43static unsigned int table_size, table_cnt; 42static unsigned int table_size, table_cnt;
44static unsigned long long _text, _stext, _etext, _sinittext, _einittext; 43static unsigned long long _text, _stext, _etext, _sinittext, _einittext;
@@ -198,8 +197,10 @@ static void read_map(FILE *in)
198 exit (1); 197 exit (1);
199 } 198 }
200 } 199 }
201 if (read_symbol(in, &table[table_cnt]) == 0) 200 if (read_symbol(in, &table[table_cnt]) == 0) {
201 table[table_cnt].start_pos = table_cnt;
202 table_cnt++; 202 table_cnt++;
203 }
203 } 204 }
204} 205}
205 206
@@ -502,6 +503,35 @@ static void optimize_token_table(void)
502 optimize_result(); 503 optimize_result();
503} 504}
504 505
506static int compare_symbols(const void *a, const void *b)
507{
508 const struct sym_entry *sa;
509 const struct sym_entry *sb;
510 int wa, wb;
511
512 sa = a;
513 sb = b;
514
515 /* sort by address first */
516 if (sa->addr > sb->addr)
517 return 1;
518 if (sa->addr < sb->addr)
519 return -1;
520
521 /* sort by "weakness" type */
522 wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
523 wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
524 if (wa != wb)
525 return wa - wb;
526
527 /* sort by initial order, so that other symbols are left undisturbed */
528 return sa->start_pos - sb->start_pos;
529}
530
531static void sort_symbols(void)
532{
533 qsort(table, table_cnt, sizeof(struct sym_entry), compare_symbols);
534}
505 535
506int main(int argc, char **argv) 536int main(int argc, char **argv)
507{ 537{
@@ -523,6 +553,7 @@ int main(int argc, char **argv)
523 usage(); 553 usage();
524 554
525 read_map(stdin); 555 read_map(stdin);
556 sort_symbols();
526 optimize_token_table(); 557 optimize_token_table();
527 write_src(); 558 write_src();
528 559