* Mathieu Desnoyers ([email protected]) wrote:
> > [...]
> > kallsyms returns the first symbol encountered, even though it is weak,
> > when it should in fact return sys_ni_syscall.
> > Is it a concern for anyone else out there ? Would it make sense to fix
> > it ?
>
> I don't know if it is a concern, but if we're going to fix it, we should
> probably do it in "scripts/kallsyms" by providing a list that is already
> sorted according to "address, weakness".
>
> This way the run-time kernel keeps the current behavior, without any
> overhead. Something along the lines of the attached patch (just compile
> tested).
>
> However, this is an area where we've had problems in the past with some
> architectures giving different results between passes, and then any change
> to the symbol order might make the problem worse and make the build process
> fail with a "Inconsistent kallsyms data" error message.
>
> So, if someone wants to use this, it should go through -mm for a while,
> first.
>
> It applies on top of 2.6.24-rc2-git3.
>
Please use this reply with correct CC list for further discussion.
> From: Paulo Marques <[email protected]>
> Signed-off-by: Mathieu Desnoyers <[email protected]>
> CC: Rusty Russell <[email protected]>
> ---
> scripts/kallsyms.c | 36 ++++++++++++++++++++++++++++++++++--
> 1 file changed, 34 insertions(+), 2 deletions(-)
>
> Index: linux-2.6-lttng/scripts/kallsyms.c
> ===================================================================
> --- linux-2.6-lttng.orig/scripts/kallsyms.c 2007-10-31 21:38:36.000000000 -0400
> +++ linux-2.6-lttng/scripts/kallsyms.c 2007-10-31 22:29:28.000000000 -0400
> @@ -34,7 +34,7 @@
>
> struct sym_entry {
> unsigned long long addr;
> - unsigned int len;
> + unsigned int len, start_pos;
> unsigned char *sym;
> };
>
> @@ -202,8 +202,10 @@ 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++;
> + }
> }
> }
>
> @@ -507,6 +509,35 @@ static void optimize_token_table(void)
> }
>
>
> +static int compare_symbols(const void *a, const void *b)
> +{
> + struct sym_entry *sa, *sb;
> + int wa, wb;
> +
> + sa = (struct sym_entry *) a;
> + sb = (struct sym_entry *) 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)
> {
> if (argc >= 2) {
> @@ -527,6 +558,7 @@ int main(int argc, char **argv)
> usage();
>
> read_map(stdin);
> + sort_symbols();
> optimize_token_table();
> write_src();
>
>
> --
> Mathieu Desnoyers
> Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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