ELF: allow non allocated sections to go into allocated sections
Patch from Andrew Kelley.
For context, see https://bugs.llvm.org/show_bug.cgi?id=39862
The use case is embedded / OS programming where the kernel wants
access to its own debug info via mapped dwarf info. I have a proof of
concept of this working, using this linker script snippet:
.rodata : ALIGN(4K) {
*(.rodata)
__debug_info_start = .;
KEEP(*(.debug_info))
__debug_info_end = .;
__debug_abbrev_start = .;
KEEP(*(.debug_abbrev))
__debug_abbrev_end = .;
__debug_str_start = .;
KEEP(*(.debug_str))
__debug_str_end = .;
__debug_line_start = .;
KEEP(*(.debug_line))
__debug_line_end =
.;
__debug_ranges_start
= .;
KEEP(*(.debug_ranges))
__debug_ranges_end
= .;
}
Differential revision: https://reviews.llvm.org/D55276
git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@348291 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/ELF/OutputSections.cpp b/ELF/OutputSections.cpp
index 8ad01e3..c1442c0 100644
--- a/ELF/OutputSections.cpp
+++ b/ELF/OutputSections.cpp
@@ -95,7 +95,7 @@
Flags = IS->Flags;
} else {
// Otherwise, check if new type or flags are compatible with existing ones.
- unsigned Mask = SHF_ALLOC | SHF_TLS | SHF_LINK_ORDER;
+ unsigned Mask = SHF_TLS | SHF_LINK_ORDER;
if ((Flags & Mask) != (IS->Flags & Mask))
error("incompatible section flags for " + Name + "\n>>> " + toString(IS) +
": 0x" + utohexstr(IS->Flags) + "\n>>> output section " + Name +
diff --git a/test/ELF/linkerscript/merge-nonalloc.s b/test/ELF/linkerscript/merge-nonalloc.s
new file mode 100644
index 0000000..7c48d3b
--- /dev/null
+++ b/test/ELF/linkerscript/merge-nonalloc.s
@@ -0,0 +1,14 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: echo "SECTIONS { .text : { *(.text) *(.nonalloc) } }" > %t.script
+# RUN: ld.lld -shared -o %t.exe %t.script %t.o
+# RUN: llvm-objdump -syms %t.exe | FileCheck %s
+
+# CHECK: .text 00000000 nonalloc_start
+
+_start:
+ nop
+
+.section .nonalloc,"",@progbits
+nonalloc_start:
+ .long 0xcafe
