aboutsummaryrefslogtreecommitdiff
path: root/scripts/kallsyms.c
diff options
context:
space:
mode:
authorPaulo Marques <pmarques@grupopie.com>2008-02-06 01:37:33 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-06 10:41:07 -0800
commitf2df3f65d0b4337cfb5b19eab3ee28b177427c49 (patch)
tree86d8aae1e9ef8c57721c886f67a915ba1897dc69 /scripts/kallsyms.c
parenta6752f3f538e9dc0d0e7fdb2080532554a5eb395 (diff)
downloadleg-kernel-f2df3f65d0b4337cfb5b19eab3ee28b177427c49.tar.gz
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 @@
#define KSYM_NAME_LEN 128
-
struct sym_entry {
unsigned long long addr;
unsigned int len;
+ unsigned int start_pos;
unsigned char *sym;
};
-
static struct sym_entry *table;
static unsigned int table_size, table_cnt;
static unsigned long long _text, _stext, _etext, _sinittext, _einittext;
@@ -198,8 +197,10 @@ static void read_map(FILE *in)
exit (1);
}
}
- if (read_symbol(in, &table[table_cnt]) == 0)
+ if (read_symbol(in, &table[table_cnt]) == 0) {
+ table[table_cnt].start_pos = table_cnt;
table_cnt++;
+ }
}
}
@@ -502,6 +503,35 @@ static void optimize_token_table(void)
optimize_result();
}
+static int compare_symbols(const void *a, const void *b)
+{
+ const struct sym_entry *sa;
+ const struct sym_entry *sb;
+ int wa, wb;
+
+ sa = a;
+ sb = b;
+
+ /* sort by address first */
+ if (sa->addr > sb->addr)
+ return 1;
+ if (sa->addr < sb->addr)
+ return -1;
+
+ /* sort by "weakness" type */
+ wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
+ wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
+ if (wa != wb)
+ return wa - wb;
+
+ /* sort by initial order, so that other symbols are left undisturbed */
+ return sa->start_pos - sb->start_pos;
+}
+
+static void sort_symbols(void)
+{
+ qsort(table, table_cnt, sizeof(struct sym_entry), compare_symbols);
+}
int main(int argc, char **argv)
{
@@ -523,6 +553,7 @@ int main(int argc, char **argv)
usage();
read_map(stdin);
+ sort_symbols();
optimize_token_table();
write_src();