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
62 lines
1.2 KiB
ArmAsm
62 lines
1.2 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-readobj -sections %tout | FileCheck %s
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# Check that sections are laid out in the correct order.
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.global _start
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.text
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_start:
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.section t,"x",@nobits
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.section s,"x"
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.section r,"w",@nobits
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.section q,"w"
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.section p,"wx",@nobits
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.section o,"wx"
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.section n,"",@nobits
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.section m,""
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.section l,"awx",@nobits
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.section k,"awx"
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.section j,"aw",@nobits
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.section i,"aw"
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.section g,"awT",@nobits
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.section e,"awT"
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.section d,"ax",@nobits
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.section c,"ax"
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.section a,"a",@nobits
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.section b,"a"
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// For non-executable and non-writable sections, PROGBITS appear after others.
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// CHECK: Name: a
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// CHECK: Name: b
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// CHECK: Name: c
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// CHECK: Name: d
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// Sections that are both writable and executable appear before
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// sections that are only writable.
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// CHECK: Name: k
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// CHECK: Name: l
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// TLS sections are only sorted on NOBITS.
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// CHECK: Name: e
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// CHECK: Name: g
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// Writable sections appear after TLS and other relro sections.
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// CHECK: Name: i
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// CHECK: Name: j
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// Non allocated sections are in input order.
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// CHECK: Name: t
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// CHECK: Name: s
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// CHECK: Name: r
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// CHECK: Name: q
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// CHECK: Name: p
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// CHECK: Name: o
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// CHECK: Name: n
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// CHECK: Name: m
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