diff mbox series

elf: Inline do_tunable_update_val/tunable_initialize [BZ #28712]

Message ID 20211218200207.3034783-1-hjl.tools@gmail.com
State Dropped
Headers show
Series elf: Inline do_tunable_update_val/tunable_initialize [BZ #28712] | expand

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit success Build for i686

Commit Message

H.J. Lu Dec. 18, 2021, 8:02 p.m. UTC
In static PIE, __tunables_init is called before _dl_relocate_static_pie
in LIBC_START_MAIN in csu/libc-start.c:

  __tunables_init (__environ);

  ARCH_INIT_CPU_FEATURES ();

  /* Do static pie self relocation after tunables and cpu features
     are setup for ifunc resolvers. Before this point relocations
     must be avoided.  */
  _dl_relocate_static_pie ();

  /* Perform IREL{,A} relocations.  */
  ARCH_SETUP_IREL ();

Inline do_tunable_update_val and tunable_initialize to prevent compiler
from generating dynamic relocation against tunable_list which causes
__tunables_init to fail in static PIE on x86-64:

FAIL: elf/tst-env-setuid

since

.L35:
        movq    $-88, %rax
        subq    .LC3(%rip), %rax
	^^^^  This is executed before the .LC3 entry has been relocated.
        movq    %rax, 8(%rsp)
...
        .section        .data.rel.ro.local,"aw"
        .align 8
.LC3:
        .quad   tunable_list

Tested on x86-64, x32 and i686 with GCC 11 and GCC 12.

This fixes BZ #28712.
---
 elf/dl-tunables.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Andreas Schwab Dec. 18, 2021, 8:13 p.m. UTC | #1
On Dez 18 2021, H.J. Lu via Libc-alpha wrote:

> diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
> index 497e948f1c..294ad81200 100644
> --- a/elf/dl-tunables.c
> +++ b/elf/dl-tunables.c
> @@ -92,7 +92,7 @@ get_next_env (char **envp, char **name, size_t *namelen, char **val,
>    return NULL;
>  }
>  
> -static void
> +static void inline
>  do_tunable_update_val (tunable_t *cur, const tunable_val_t *valp,
>  		       const tunable_num_t *minp,
>  		       const tunable_num_t *maxp)

That shouldn't make a difference since static functions are already
inlineable.  If you want to force inlining you need to use
always_inline.
H.J. Lu Dec. 18, 2021, 8:28 p.m. UTC | #2
On Sat, Dec 18, 2021 at 12:14 PM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Dez 18 2021, H.J. Lu via Libc-alpha wrote:
>
> > diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
> > index 497e948f1c..294ad81200 100644
> > --- a/elf/dl-tunables.c
> > +++ b/elf/dl-tunables.c
> > @@ -92,7 +92,7 @@ get_next_env (char **envp, char **name, size_t *namelen, char **val,
> >    return NULL;
> >  }
> >
> > -static void
> > +static void inline
> >  do_tunable_update_val (tunable_t *cur, const tunable_val_t *valp,
> >                      const tunable_num_t *minp,
> >                      const tunable_num_t *maxp)
>
> That shouldn't make a difference since static functions are already
> inlineable.  If you want to force inlining you need to use
> always_inline.
>

Fixed in the v2 patch.

Thanks.
diff mbox series

Patch

diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index 497e948f1c..294ad81200 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -92,7 +92,7 @@  get_next_env (char **envp, char **name, size_t *namelen, char **val,
   return NULL;
 }
 
-static void
+static void inline
 do_tunable_update_val (tunable_t *cur, const tunable_val_t *valp,
 		       const tunable_num_t *minp,
 		       const tunable_num_t *maxp)
@@ -139,7 +139,7 @@  do_tunable_update_val (tunable_t *cur, const tunable_val_t *valp,
 
 /* Validate range of the input value and initialize the tunable CUR if it looks
    good.  */
-static void
+static void inline
 tunable_initialize (tunable_t *cur, const char *strval)
 {
   tunable_val_t val;