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Commit 9aa4ec15 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
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arm64: mm: fold alternatives into .init 



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: default avatarMark 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: default avatarWill Deacon <will.deacon@arm.com>
parent 5b28cd9d

arch/arm64/include/asm/alternative.h

+0 −1
Original line number Diff line number Diff line
@@ -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           */ \

arch/arm64/kernel/alternative.c

+0 −6
Original line number Diff line number Diff line
@@ -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");

}

arch/arm64/kernel/vmlinux.lds.S

+2 −3
Original line number Diff line number Diff line
@@ -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)

arch/arm64/mm/init.c

+0 −1
Original line number Diff line number Diff line
@@ -360,7 +360,6 @@ void free_initmem(void) 
{

	fixup_init();

	free_initmem_default(0);

	free_alternatives_memory();

}



#ifdef CONFIG_BLK_DEV_INITRD