Commit eb4b5a36 authored by Fangrui Song's avatar Fangrui Song
Browse files

[ELF] Move --print-map(-M)/--cref before checkSections() and openFile() 

-M output can be useful when diagnosing an "error: output file too large" problem (emitted in openFile()).

I just ran into such a situation where I had to debug an erronerous
Linux kernel linker script. It tried to create a file larger than
INT64_MAX bytes.

This patch could have helped https://bugs.llvm.org/show_bug.cgi?id=44715 as well.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D75966
parent 7c2b3c9d

lld/ELF/Writer.cpp

+6 −6
Original line number Diff line number Diff line
@@ -595,6 +595,12 @@ template <class ELFT> void Writer<ELFT>::run() { 
    for (OutputSection *sec : outputSections)

      sec->addr = 0;



  // Handle --print-map(-M)/--Map and --cref. Dump them before checkSections()

  // because the files may be useful in case checkSections() or openFile()

  // fails, for example, due to an erroneous file size.

  writeMapFile();

  writeCrossReferenceTable();



  if (config->checkSections)

    checkSections();
@@ -621,12 +627,6 @@ template <class ELFT> void Writer<ELFT>::run() { 
  if (errorCount())

    return;



  // Handle -Map and -cref options.

  writeMapFile();

  writeCrossReferenceTable();

  if (errorCount())

    return;



  if (auto e = buffer->commit())

    error("failed to write to the output file: " + toString(std::move(e)));

}

lld/test/ELF/linkerscript/output-too-large.s

+25 −6
Original line number Diff line number Diff line 
# REQUIRES: x86



# RUN: llvm-mc -filetype=obj -triple=i686-unknown-linux %s -o %t.o

# RUN: echo "SECTIONS { .text : { . = 0xffffffff; *(.text*); } }" > %t.script

# RUN: not ld.lld --no-check-sections --script %t.script %t.o -o /dev/null 2>&1 | FileCheck %s

# RUN: llvm-mc -filetype=obj -triple=i686 %s -o %t1.o

# RUN: echo "SECTIONS { .text : { . = 0xffffffff; *(.text*); } }" > %t1.script

# RUN: not ld.lld --no-check-sections -T %t1.script %t1.o -o /dev/null 2>&1 | FileCheck %s



# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o

# RUN: echo "SECTIONS { .text : { . = 0x8fffffffffffffff; *(.text*); } }" > %t.script

# RUN: not ld.lld --no-check-sections --script %t.script %t.o -o /dev/null 2>&1 | FileCheck %s

## Error if an address is greater than or equal to 2**32 for ELF32.

## When -M is specified, print the link map even if such an error occurs,

## because the link map can help diagnose problems.

# RUN: not ld.lld -T %t1.script %t1.o -M -o /dev/null 2>&1 | \

# RUN:   FileCheck --check-prefix=MAP1 %s



# MAP1:           VMA      LMA     Size Align Out     In      Symbol

# MAP1-NEXT:        0        0 100000001     4 .text

# MAP1-NEXT:        0        0 ffffffff     1         . = 0xffffffff

# MAP1-NEXT: 100000000 100000000        1     4         {{.*}}.o:(.text)

# MAP1:      error: section .text at 0x0 of size 0x100000001 exceeds available address space



## Error if an address is greater than or equal to 2**63.

## Print a link map if -M is specified.

# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t2.o

# RUN: echo "SECTIONS { .text : { . = 0x8fffffffffffffff; *(.text*); } }" > %t2.script

# RUN: not ld.lld -T %t2.script -M %t2.o -o /dev/null 2>&1 | \

# RUN:   FileCheck --check-prefixes=MAP2,CHECK %s



# MAP2:                   VMA              LMA     Size Align Out     In      Symbol

# MAP2:      9000000000000000 9000000000000000        1     4         {{.*}}.o:(.text)

# MAP2-NEXT: 9000000000000000 9000000000000000        0     1                 _start



# CHECK: error: output file too large