H.J. Lu 8dcea93252 Add -mshared option to x86 ELF assembler ... This patch adds -mshared option to x86 ELF assembler. By default, assembler will optimize out non-PLT relocations against defined non-weak global branch targets with default visibility. The -mshared option tells the assembler to generate code which may go into a shared library where all non-weak global branch targets with default visibility can be preempted. The resulting code is slightly bigger. This option only affects the handling of branch instructions. This Linux kernel patch is needed to create a working x86 Linux kernel if it hasn't been applied: diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index ae6588b..b91a00c 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -339,8 +339,8 @@ early_idt_handlers: i = i + 1 .endr -/* This is global to keep gas from relaxing the jumps */ -ENTRY(early_idt_handler) +/* This is weak to keep gas from relaxing the jumps */ +WEAK(early_idt_handler) cld cmpl $2,(%rsp) # X86_TRAP_NMI -- gas/ * config/tc-i386.c (shared): New. (OPTION_MSHARED): Likewise. (elf_symbol_resolved_in_segment_p): Add relocation argument. Check PLT relocations and shared. (md_estimate_size_before_relax): Pass fragP->fr_var to elf_symbol_resolved_in_segment_p. (md_longopts): Add -mshared. (md_show_usage): Likewise. (md_parse_option): Handle OPTION_MSHARED. * doc/c-i386.texi: Document -mshared. gas/testsuite/ * gas/i386/i386.exp: Don't run pcrel for ELF targets. Run pcrel-elf, relax-4 and x86-64-relax-3 for ELF targets. * gas/i386/pcrel-elf.d: New file. * gas/i386/relax-4.d: Likewise. * gas/i386/x86-64-relax-3.d: Likewise. * gas/i386/relax-3.d: Pass -mshared to assembler. Updated. * gas/i386/x86-64-relax-2.d: Likewise. * gas/i386/relax-3.s: Add test for PLT relocation.		2015-05-15 03:30:53 -07:00
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config
gas	Add -mshared option to x86 ELF assembler	2015-05-15 03:30:53 -07:00
lib	Remove is_zlib_supported	2015-04-06 12:19:13 -07:00
ChangeLog	Add -mshared option to x86 ELF assembler	2015-05-15 03:30:53 -07:00
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