Commit 504665a9 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] module function call optimization 



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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent e13ed9b2

arch/s390/kernel/module.c

+12 −7
Original line number Diff line number Diff line
@@ -310,15 +310,20 @@ apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, 
			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

		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 + 

				rela->r_addend - loc;

					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)

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