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powerpc/8xx: Reduce default size of module/execmem area

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8xx boards don't have much memory, the two I know have respectively
32Mbytes and 128Mbytes, so there is no point in having 256 Mbytes of
memory for module text.

Reduce it to 32Mbytes for 8xx, that's more than enough.

Nevertheless, make it a configurable value so that it can be customised
if needed.

Also add a build verification for overlap of module execmem space
with user PMD.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/8db23b61e33a0d1913d814f94bfe71ba7ac78b0f.1724173828.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2024-08-20 19:23:50 +02:00 committed by Michael Ellerman
parent bcf77a70c4
commit c5eec4df25
3 changed files with 22 additions and 1 deletions
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18
arch/powerpc/Kconfig
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@ -1271,6 +1271,24 @@ config TASK_SIZE
default "0x80000000" if PPC_8xx
default "0xb0000000" if PPC_BOOK3S_32
default "0xc0000000"
config MODULES_SIZE_BOOL
bool "Set custom size for modules/execmem area"
depends on EXECMEM && ADVANCED_OPTIONS
depends on PPC_8xx
help
This option allows you to set the size of kernel virtual address
space dedicated for modules/execmem.
For the time being it is only for 8xx.
Say N here unless you know what you are doing.
config MODULES_SIZE
int "Size of modules/execmem area (In Mbytes)" if MODULES_SIZE_BOOL
range 1 256 if EXECMEM
default 32 if EXECMEM && PPC_8xx
default 0
endmenu
if PPC64

3
arch/powerpc/include/asm/nohash/32/mmu-8xx.h
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@ -170,8 +170,9 @@
#define mmu_linear_psize MMU_PAGE_8M
#define MODULES_VADDR (PAGE_OFFSET - SZ_256M)
#define MODULES_END PAGE_OFFSET
#define MODULES_SIZE (CONFIG_MODULES_SIZE * SZ_1M)
#define MODULES_VADDR (MODULES_END - MODULES_SIZE)
#ifndef __ASSEMBLY__

2
arch/powerpc/mm/nohash/8xx.c
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@ -207,6 +207,8 @@ void __init setup_initial_memory_limit(phys_addr_t first_memblock_base,
/* 8xx can only access 32MB at the moment */
memblock_set_current_limit(min_t(u64, first_memblock_size, SZ_32M));
BUILD_BUG_ON(ALIGN_DOWN(MODULES_VADDR, PGDIR_SIZE) < TASK_SIZE);
}
int pud_clear_huge(pud_t *pud)