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powerpc/32s: Reduce default size of module/execmem area

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book3s/32 platforms have usually more memory than 8xx, but it is still
not worth reserving a full segment (256 Mbytes) for module text.
64Mbytes should be far enough.

Also fix TASK_SIZE when EXECMEM is not selected, and add a build
verification for overlap of module execmem space with user segments.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/c1f6a4e47f177d919561c6e97d31af5564923cf6.1724173828.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2024-08-20 19:23:54 +02:00 committed by Michael Ellerman
parent ac9f97ff8b
commit 2f2b9a3adc
3 changed files with 8 additions and 4 deletions
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7
arch/powerpc/Kconfig
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@ -1269,23 +1269,24 @@ config TASK_SIZE_BOOL
config TASK_SIZE
hex "Size of user task space" if TASK_SIZE_BOOL
default "0x80000000" if PPC_8xx
default "0xb0000000" if PPC_BOOK3S_32
default "0xb0000000" if PPC_BOOK3S_32 && EXECMEM
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.
For the time being it is only for 8xx and book3s/32. Other
platform share it with vmalloc space.
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 64 if EXECMEM && PPC_BOOK3S_32
default 32 if EXECMEM && PPC_8xx
default 0

3
arch/powerpc/include/asm/book3s/32/pgtable.h
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@ -196,7 +196,8 @@ void unmap_kernel_page(unsigned long va);
#endif
#define MODULES_END ALIGN_DOWN(PAGE_OFFSET, SZ_256M)
#define MODULES_VADDR (MODULES_END - SZ_256M)
#define MODULES_SIZE (CONFIG_MODULES_SIZE * SZ_1M)
#define MODULES_VADDR (MODULES_END - MODULES_SIZE)
#ifndef __ASSEMBLY__
#include <linux/sched.h>

2
arch/powerpc/mm/book3s32/mmu.c
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@ -223,6 +223,8 @@ int mmu_mark_initmem_nx(void)
update_bats();
BUILD_BUG_ON(ALIGN_DOWN(MODULES_VADDR, SZ_256M) < TASK_SIZE);
for (i = TASK_SIZE >> 28; i < 16; i++) {
/* Do not set NX on VM space for modules */
if (is_module_segment(i << 28))