Commit b150a4d1 authored by Michael Ellerman's avatar Michael Ellerman
Browse files

powerpc/vmlinux.lds: Add an explicit symbol for the SRWX boundary 



Currently __init_begin is used as the boundary for strict RWX between
executable/read-only text and data, and non-executable (after boot) code
and data.

But that's a little subtle, so add an explicit symbol to document that
the SRWX boundary lies there, and add a comment making it clear that
__init_begin must also begin there.

Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220916131422.318752-2-mpe@ellerman.id.au
parent 331771e8

arch/powerpc/include/asm/sections.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ typedef struct func_desc func_desc_t; 
#include <asm-generic/sections.h>



extern char __head_end[];

extern char __srwx_boundary[];



/* Patch sites */

extern s32 patch__call_flush_branch_caches1;

arch/powerpc/kernel/vmlinux.lds.S

+7 −2
Original line number Diff line number Diff line
@@ -215,10 +215,15 @@ SECTIONS 
#endif



	/*

 * Init sections discarded at runtime

	 * Various code relies on __init_begin being at the strict RWX boundary.

	 */

	. = ALIGN(STRICT_ALIGN_SIZE);

	__srwx_boundary = .;

	__init_begin = .;



/*

 * Init sections discarded at runtime

 */

	.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {

		_sinittext = .;

		INIT_TEXT

arch/powerpc/mm/book3s32/mmu.c

+1 −1
Original line number Diff line number Diff line
@@ -158,7 +158,7 @@ static unsigned long __init __mmu_mapin_ram(unsigned long base, unsigned long to 
unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)

{

	unsigned long done;

	unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;

	unsigned long border = (unsigned long)__srwx_boundary - PAGE_OFFSET;

	unsigned long size;



	size = roundup_pow_of_two((unsigned long)_einittext - PAGE_OFFSET);

arch/powerpc/mm/book3s64/radix_pgtable.c

+2 −2
Original line number Diff line number Diff line
@@ -259,8 +259,8 @@ print_mapping(unsigned long start, unsigned long end, unsigned long size, bool e 
static unsigned long next_boundary(unsigned long addr, unsigned long end)

{

#ifdef CONFIG_STRICT_KERNEL_RWX

	if (addr < __pa_symbol(__init_begin))

		return __pa_symbol(__init_begin);

	if (addr < __pa_symbol(__srwx_boundary))

		return __pa_symbol(__srwx_boundary);

#endif

	return end;

}