[klibc] [PATCH] x86_64: Reduce ld max-page-size option again
Ben Hutchings
ben at decadent.org.uk
Mon Jul 16 19:55:53 PDT 2018
Building klibc with binutils 2.30 results in the following layout
for klibc.so:
Idx Name Size VMA LMA File off Algn
0 .text 0000d1ff 0000000000200200 0000000000200200 00000200 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .rodata 000031af 0000000000300000 0000000000300000 00100000 2**5
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .data.rel.ro 00000990 0000000000403660 0000000000403660 00103660 2**5
CONTENTS, ALLOC, LOAD, DATA
3 .data 00000140 0000000000404000 0000000000404000 00104000 2**5
CONTENTS, ALLOC, LOAD, DATA
4 .bss 000042f8 0000000000404140 0000000000404140 00104140 2**5
ALLOC
The .text and .rodata sections have each been padded to the specified
maximum page size of 1 MB, causing the following sections to overlap
the executable.
This causes all klibc executables to crash immediately.
Since there's no architectural page size betwen 4 KB and 2MB, set
max-page-size to 4 KB.
Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
---
--- a/usr/klibc/arch/x86_64/MCONFIG
+++ b/usr/klibc/arch/x86_64/MCONFIG
@@ -30,10 +30,12 @@ KLIBCLDFLAGS = -m elf_x86_64
# calls, and work on the memory models for this architecture
# 2 MB - normal binaries start at 4 MB
#
-# Recent binutils use max-page-size=0x200000 by default, which pushes
+# binutils now uses max-page-size=0x200000 by default, which pushes
# klibc.so data over the 4 MB mark, overlapping the executable.
-# Revert to the old max-page-size=0x100000 value.
-KLIBCSHAREDFLAGS = -Ttext 0x00200200 -z max-page-size=0x100000
+# The old default was max-page-size=0x100000, but that also results
+# in a broken layout with binutils 2.30. Since there's no
+# architectural page size betwen 4 KB and 2MB, set it to 4 KB.
+KLIBCSHAREDFLAGS = -Ttext 0x00200200 -z max-page-size=0x1000
# Asm includes for x86_64 are in the merged x86 tree
KLIBCARCHINCFLAGS = -I$(KLIBCKERNELOBJ)/arch/x86/include
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