Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f2df3f65d0b4337cfb5b19eab3ee28b177427c49
Commit: f2df3f65d0b4337cfb5b19eab3ee28b177427c49
Parent: a6752f3f538e9dc0d0e7fdb2080532554a5eb395
Author: Paulo Marques <[EMAIL PROTECTED]>
AuthorDate: Wed Feb 6 01:37:33 2008 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed Feb 6 10:41:07 2008 -0800
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.
[EMAIL PROTECTED]: coding-style fixes]
Signed-off-by: Mathieu Desnoyers <[EMAIL PROTECTED]>
Looks-great-to: Rusty Russell <[EMAIL PROTECTED]>
Cc: Sam Ravnborg <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
scripts/kallsyms.c | 37 ++++++++++++++++++++++++++++++++++---
1 files changed, 34 insertions(+), 3 deletions(-)
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 8fb8700..c912137 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();
-
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