From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
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@xxxxxxxxxx>
---
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.
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