lkml.org 
[lkml]   [2009]   [Feb]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch/s390 43/46] module function call optimization
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Avoid the detour over the PLT if the branch target of a function call
in a module is in the range of the bras (16-bit) or brasl (32-bit)
instruction. The PLT is still generated but it is unused.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

arch/s390/kernel/module.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)

Index: quilt-2.6/arch/s390/kernel/module.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/module.c
+++ quilt-2.6/arch/s390/kernel/module.c
@@ -310,15 +310,20 @@ apply_rela(Elf_Rela *rela, Elf_Addr base
info->plt_initialized = 1;
}
if (r_type == R_390_PLTOFF16 ||
- r_type == R_390_PLTOFF32
- || r_type == R_390_PLTOFF64
- )
+ r_type == R_390_PLTOFF32 ||
+ r_type == R_390_PLTOFF64)
val = me->arch.plt_offset - me->arch.got_offset +
info->plt_offset + rela->r_addend;
- else
- val = (Elf_Addr) me->module_core +
- me->arch.plt_offset + info->plt_offset +
- rela->r_addend - loc;
+ else {
+ if (!((r_type == R_390_PLT16DBL &&
+ val - loc + 0xffffUL < 0x1ffffeUL) ||
+ (r_type == R_390_PLT32DBL &&
+ val - loc + 0xffffffffULL < 0x1fffffffeULL)))
+ val = (Elf_Addr) me->module_core +
+ me->arch.plt_offset +
+ info->plt_offset;
+ val += rela->r_addend - loc;
+ }
if (r_type == R_390_PLT16DBL)
*(unsigned short *) loc = val >> 1;
else if (r_type == R_390_PLTOFF16)
--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.



\
 
 \ /
  Last update: 2009-02-25 16:23    [W:0.279 / U:0.272 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site