07f8daf05e
Old: PT_LOAD(.data | PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .bss) New: PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .data .bss) The placement of | indicates page alignment caused by PT_GNU_RELRO. The new layout has simpler rules and saves space for many cases. Old size: roundup(.data) + roundup(.data.rel.ro) New size: roundup(.data.rel.ro + .bss.rel.ro) + .data Other advantages: * At runtime the 3 memory mappings decrease to 2. * start(PT_TLS) = start(PT_GNU_RELRO) = start(RW PT_LOAD). This simplifies binary manipulation tools. GNU strip before 2.31 discards PT_GNU_RELRO if its address is not equal to the start of its associated PT_LOAD. This has been fixed by https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f2731e0c374e5323ce4cdae2bcc7b7fe22da1a6f But with this change, we will be compatible with GNU strip before 2.31 * Before, .got.plt (non-relro by default) was placed before .got (relro by default), which made it impossible to have _GLOBAL_OFFSET_TABLE_ (start of .got.plt on x86-64) equal to the end of .got (R_GOT*_FROM_END) (https://bugs.llvm.org/show_bug.cgi?id=36555). With the new ordering, we can improve on this regard if we'd like to. Reviewers: ruiu, espindola, pcc Subscribers: emaste, arichardson, llvm-commits, joerg, jdoerfert Differential Revision: https://reviews.llvm.org/D56828 llvm-svn: 356117
59 lines
1.3 KiB
ArmAsm
59 lines
1.3 KiB
ArmAsm
# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
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# RUN: ld.lld %t -o %tout
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# RUN: llvm-objdump --section-headers %tout | FileCheck %s
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.global _start
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.text
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_start:
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.section .text.a,"ax"
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.byte 0
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.section .text.,"ax"
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.byte 0
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.section .rodata.a,"a"
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.byte 0
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.section .rodata,"a"
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.byte 0
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.section .data.a,"aw"
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.byte 0
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.section .data,"aw"
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.byte 0
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.section .bss.a,"aw",@nobits
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.byte 0
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.section .bss,"aw",@nobits
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.byte 0
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.section .foo.a,"aw"
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.byte 0
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.section .foo,"aw"
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.byte 0
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.section .data.rel.ro,"aw",%progbits
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.byte 0
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.section .data.rel.ro.a,"aw",%progbits
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.byte 0
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.section .data.rel.ro.local,"aw",%progbits
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.byte 0
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.section .data.rel.ro.local.a,"aw",%progbits
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.byte 0
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.section .tbss.foo,"aGwT",@nobits,foo,comdat
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.byte 0
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.section .gcc_except_table.foo,"aG",@progbits,foo,comdat
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.byte 0
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.section .tdata.foo,"aGwT",@progbits,foo,comdat
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.byte 0
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// CHECK: 1 .rodata 00000002
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// CHECK: 2 .gcc_except_table 00000001
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// CHECK: 3 .text 00000002
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// CHECK: 4 .tdata 00000001
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// CHECK: 5 .tbss 00000001
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// CHECK: 6 .data.rel.ro 00000004
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// CHECK: 7 .data 00000002
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// CHECK: 8 .foo.a 00000001
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// CHECK: 9 .foo 00000001
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// CHECK: 10 .bss 00000002
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// CHECK: 11 .comment 00000008
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// CHECK: 12 .symtab 00000030
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// CHECK: 13 .shstrtab 00000075
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// CHECK: 14 .strtab 00000008
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