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arm64: mm: fold alternatives into .init

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Currently we treat the alternatives separately from other data that's
only used during initialisation, using separate .altinstructions and
.altinstr_replacement linker sections. These are freed for general
allocation separately from .init*. This is problematic as:

* We do not remove execute permissions, as we do for .init, leaving the
  memory executable.

* We pad between them, making the kernel Image bianry up to PAGE_SIZE
  bytes larger than necessary.

This patch moves the two sections into the contiguous region used for
.init*. This saves some memory, ensures that we remove execute
permissions, and allows us to remove some code made redundant by this
reorganisation.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mark Rutland 2015-12-09 12:44:38 +00:00 committed by Will Deacon
parent 5b28cd9d08
commit 9aa4ec1571
4 changed files with 2 additions and 11 deletions
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1
arch/arm64/include/asm/alternative.h
View File

@ -19,7 +19,6 @@ struct alt_instr {
void __init apply_alternatives_all(void);
void apply_alternatives(void *start, size_t length);
void free_alternatives_memory(void);
#define ALTINSTR_ENTRY(feature) \
" .word 661b - .\n" /* label */ \

6
arch/arm64/kernel/alternative.c
View File

@ -158,9 +158,3 @@ void apply_alternatives(void *start, size_t length)
__apply_alternatives(&region);
}
void free_alternatives_memory(void)
{
free_reserved_area(__alt_instructions, __alt_instructions_end,
0, "alternatives");
}

5
arch/arm64/kernel/vmlinux.lds.S
View File

@ -140,9 +140,6 @@ SECTIONS
PERCPU_SECTION(64)
. = ALIGN(PAGE_SIZE);
__init_end = .;
. = ALIGN(4);
.altinstructions : {
__alt_instructions = .;
@ -154,6 +151,8 @@ SECTIONS
}
. = ALIGN(PAGE_SIZE);
__init_end = .;
_data = .;
_sdata = .;
RW_DATA_SECTION(64, PAGE_SIZE, THREAD_SIZE)

1
arch/arm64/mm/init.c
View File

@ -360,7 +360,6 @@ void free_initmem(void)
{
fixup_init();
free_initmem_default(0);
free_alternatives_memory();
}
#ifdef CONFIG_BLK_DEV_INITRD