linux/arch/um/kernel/uml.lds.S
David Gow 598f563036 um: Fix overlapping ELF segments when statically linked
When statically linked, the .text section in UML kernels is not page
aligned, causing it to share a page with the executable headers. As
.text and the executable headers have different permissions, this causes
the kernel to wish to map the same page twice (once as headers with r--
permissions, once as .text with r-x permissions), causing a segfault,
and a nasty message printed to the host kernel's dmesg:

"Uhuuh, elf segment at 0000000060000000 requested but the memory is
mapped already"

By aligning the .text to a page boundary (as in the dynamically linked
version in dyn.lds.S), there is no such overlap, and the kernel runs
correctly.

Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2020-03-29 23:21:29 +02:00

116 lines
2.5 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0 */
#include <asm/vmlinux.lds.h>
#include <asm/page.h>
OUTPUT_FORMAT(ELF_FORMAT)
OUTPUT_ARCH(ELF_ARCH)
ENTRY(_start)
jiffies = jiffies_64;
SECTIONS
{
/* This must contain the right address - not quite the default ELF one.*/
PROVIDE (__executable_start = START);
/* Static binaries stick stuff here, like the sigreturn trampoline,
* invisibly to objdump. So, just make __binary_start equal to the very
* beginning of the executable, and if there are unmapped pages after this,
* they are forever unusable.
*/
__binary_start = START;
. = START + SIZEOF_HEADERS;
. = ALIGN(PAGE_SIZE);
_text = .;
INIT_TEXT_SECTION(0)
.text :
{
_stext = .;
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
*(.fixup)
/* .gnu.warning sections are handled specially by elf32.em. */
*(.gnu.warning)
*(.gnu.linkonce.t*)
}
. = ALIGN(PAGE_SIZE);
.syscall_stub : {
__syscall_stub_start = .;
*(.__syscall_stub*)
__syscall_stub_end = .;
}
/*
* These are needed even in a static link, even if they wind up being empty.
* Newer glibc needs these __rel{,a}_iplt_{start,end} symbols.
*/
.rel.plt : {
*(.rel.plt)
PROVIDE_HIDDEN(__rel_iplt_start = .);
*(.rel.iplt)
PROVIDE_HIDDEN(__rel_iplt_end = .);
}
.rela.plt : {
*(.rela.plt)
PROVIDE_HIDDEN(__rela_iplt_start = .);
*(.rela.iplt)
PROVIDE_HIDDEN(__rela_iplt_end = .);
}
#include <asm/common.lds.S>
__init_begin = .;
init.data : { INIT_DATA }
__init_end = .;
.data :
{
INIT_TASK_DATA(KERNEL_STACK_SIZE)
. = ALIGN(KERNEL_STACK_SIZE);
*(.data..init_irqstack)
DATA_DATA
*(.gnu.linkonce.d*)
CONSTRUCTORS
}
.data1 : { *(.data1) }
.ctors :
{
*(.ctors)
}
.dtors :
{
*(.dtors)
}
.got : { *(.got.plt) *(.got) }
.dynamic : { *(.dynamic) }
.tdata : { *(.tdata .tdata.* .gnu.linkonce.td.*) }
.tbss : { *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon) }
/* We want the small data sections together, so single-instruction offsets
can access them all, and initialized data all before uninitialized, so
we can shorten the on-disk segment size. */
.sdata : { *(.sdata) }
_edata = .;
PROVIDE (edata = .);
. = ALIGN(PAGE_SIZE);
__bss_start = .;
PROVIDE(_bss_start = .);
SBSS(0)
BSS(0)
__bss_stop = .;
_end = .;
PROVIDE (end = .);
STABS_DEBUG
DWARF_DEBUG
DISCARDS
}