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linux-next/arch/mips/kernel/vmlinux.lds.S
Paul Burton 3f00f4d8f0 MIPS: Ensure bss section ends on a long-aligned address
When clearing the .bss section in kernel_entry we do so using LONG_S
instructions, and branch whilst the current write address doesn't equal
the end of the .bss section minus the size of a long integer. The .bss
section always begins at a long-aligned address and we always increment
the write pointer by the size of a long integer - we therefore rely upon
the .bss section ending at a long-aligned address. If this is not the
case then the long-aligned write address can never be equal to the
non-long-aligned end address & we will continue to increment past the
end of the .bss section, attempting to zero the rest of memory.

Despite this requirement that .bss end at a long-aligned address we pass
0 as the end alignment requirement to the BSS_SECTION macro and thus
don't guarantee any particular alignment, allowing us to hit the error
condition described above.

Fix this by instead passing 8 bytes as the end alignment argument to
the BSS_SECTION macro, ensuring that the end of the .bss section is
always at least long-aligned.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14526/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2017-01-03 16:34:36 +01:00

227 lines
4.7 KiB
ArmAsm

#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#define PAGE_SIZE _PAGE_SIZE
/*
* Put .bss..swapper_pg_dir as the first thing in .bss. This will
* ensure that it has .bss alignment (64K).
*/
#define BSS_FIRST_SECTIONS *(.bss..swapper_pg_dir)
#include <asm-generic/vmlinux.lds.h>
#undef mips
#define mips mips
OUTPUT_ARCH(mips)
ENTRY(kernel_entry)
PHDRS {
text PT_LOAD FLAGS(7); /* RWX */
#ifndef CONFIG_CAVIUM_OCTEON_SOC
note PT_NOTE FLAGS(4); /* R__ */
#endif /* CAVIUM_OCTEON_SOC */
}
#ifdef CONFIG_32BIT
#ifdef CONFIG_CPU_LITTLE_ENDIAN
jiffies = jiffies_64;
#else
jiffies = jiffies_64 + 4;
#endif
#else
jiffies = jiffies_64;
#endif
SECTIONS
{
#ifdef CONFIG_BOOT_ELF64
/* Read-only sections, merged into text segment: */
/* . = 0xc000000000000000; */
/* This is the value for an Origin kernel, taken from an IRIX kernel. */
/* . = 0xc00000000001c000; */
/* Set the vaddr for the text segment to a value
* >= 0xa800 0000 0001 9000 if no symmon is going to configured
* >= 0xa800 0000 0030 0000 otherwise
*/
/* . = 0xa800000000300000; */
. = 0xffffffff80300000;
#endif
. = VMLINUX_LOAD_ADDRESS;
/* read-only */
_text = .; /* Text and read-only data */
.text : {
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
*(.text.*)
*(.fixup)
*(.gnu.warning)
} :text = 0
_etext = .; /* End of text section */
EXCEPTION_TABLE(16)
/* Exception table for data bus errors */
__dbe_table : {
__start___dbe_table = .;
*(__dbe_table)
__stop___dbe_table = .;
}
#ifdef CONFIG_CAVIUM_OCTEON_SOC
#define NOTES_HEADER
#else /* CONFIG_CAVIUM_OCTEON_SOC */
#define NOTES_HEADER :note
#endif /* CONFIG_CAVIUM_OCTEON_SOC */
NOTES :text NOTES_HEADER
.dummy : { *(.dummy) } :text
_sdata = .; /* Start of data section */
RODATA
/* writeable */
.data : { /* Data */
. = . + DATAOFFSET; /* for CONFIG_MAPPED_KERNEL */
INIT_TASK_DATA(THREAD_SIZE)
NOSAVE_DATA
CACHELINE_ALIGNED_DATA(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
READ_MOSTLY_DATA(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
DATA_DATA
CONSTRUCTORS
}
_gp = . + 0x8000;
.lit8 : {
*(.lit8)
}
.lit4 : {
*(.lit4)
}
/* 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 = .; /* End of data section */
/* will be freed after init */
. = ALIGN(PAGE_SIZE); /* Init code and data */
__init_begin = .;
INIT_TEXT_SECTION(PAGE_SIZE)
INIT_DATA_SECTION(16)
. = ALIGN(4);
.mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) {
__mips_machines_start = .;
*(.mips.machines.init)
__mips_machines_end = .;
}
/* .exit.text is discarded at runtime, not link time, to deal with
* references from .rodata
*/
.exit.text : {
EXIT_TEXT
}
.exit.data : {
EXIT_DATA
}
#ifdef CONFIG_SMP
PERCPU_SECTION(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
#endif
#ifdef CONFIG_RELOCATABLE
. = ALIGN(4);
.data.reloc : {
_relocation_start = .;
/*
* Space for relocation table
* This needs to be filled so that the
* relocs tool can overwrite the content.
* An invalid value is left at the start of the
* section to abort relocation if the table
* has not been filled in.
*/
LONG(0xFFFFFFFF);
FILL(0);
. += CONFIG_RELOCATION_TABLE_SIZE - 4;
_relocation_end = .;
}
#endif
#ifdef CONFIG_MIPS_RAW_APPENDED_DTB
__appended_dtb = .;
/* leave space for appended DTB */
. += 0x100000;
#elif defined(CONFIG_MIPS_ELF_APPENDED_DTB)
.appended_dtb : AT(ADDR(.appended_dtb) - LOAD_OFFSET) {
*(.appended_dtb)
KEEP(*(.appended_dtb))
}
#endif
/*
* Align to 64K in attempt to eliminate holes before the
* .bss..swapper_pg_dir section at the start of .bss. This
* also satisfies PAGE_SIZE alignment as the largest page size
* allowed is 64K.
*/
. = ALIGN(0x10000);
__init_end = .;
/* freed after init ends here */
/*
* Force .bss to 64K alignment so that .bss..swapper_pg_dir
* gets that alignment. .sbss should be empty, so there will be
* no holes after __init_end. */
BSS_SECTION(0, 0x10000, 8)
_end = . ;
/* These mark the ABI of the kernel for debuggers. */
.mdebug.abi32 : {
KEEP(*(.mdebug.abi32))
}
.mdebug.abi64 : {
KEEP(*(.mdebug.abi64))
}
/* This is the MIPS specific mdebug section. */
.mdebug : {
*(.mdebug)
}
STABS_DEBUG
DWARF_DEBUG
/* These must appear regardless of . */
.gptab.sdata : {
*(.gptab.data)
*(.gptab.sdata)
}
.gptab.sbss : {
*(.gptab.bss)
*(.gptab.sbss)
}
/* Sections to be discarded */
DISCARDS
/DISCARD/ : {
/* ABI crap starts here */
*(.MIPS.abiflags)
*(.MIPS.options)
*(.options)
*(.pdr)
*(.reginfo)
*(.eh_frame)
}
}