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powerpc/32s: Enable STRICT_MODULE_RWX for the 603 core

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The book3s/32 MMU doesn't support per page execution protection and
doesn't support RO protection for kernel pages.

However, on the 603 which implements software loaded TLBs, execution
protection is honored by the TLB Miss handler which doesn't load
Instruction TLB for non executable pages. And RO protection is
honored by clearing the C bit for RO pages, leading to DSI.

So on the 603, STRICT_MODULE_RWX is possible without much effort.
Don't disable STRICT_MODULE_RWX on book3s/32 and print a warning
in case STRICT_MODULE_RWX has been selected and the platform has
a Hardware HASH MMU.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1e6162f334167e75f1140082932e3a354b16daba.1642413973.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2022-01-17 10:06:39 +00:00 committed by Michael Ellerman
parent a8936569a0
commit 0670010f3b
2 changed files with 4 additions and 1 deletions
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2
arch/powerpc/Kconfig
View File

@ -135,7 +135,7 @@ config PPC
select ARCH_HAS_SET_MEMORY select ARCH_HAS_SET_MEMORY
select ARCH_HAS_STRICT_KERNEL_RWX if (PPC_BOOK3S || PPC_8xx || 40x) && !HIBERNATION select ARCH_HAS_STRICT_KERNEL_RWX if (PPC_BOOK3S || PPC_8xx || 40x) && !HIBERNATION
select ARCH_HAS_STRICT_KERNEL_RWX if FSL_BOOKE && !HIBERNATION && !RANDOMIZE_BASE select ARCH_HAS_STRICT_KERNEL_RWX if FSL_BOOKE && !HIBERNATION && !RANDOMIZE_BASE
select ARCH_HAS_STRICT_MODULE_RWX if ARCH_HAS_STRICT_KERNEL_RWX && !PPC_BOOK3S_32 select ARCH_HAS_STRICT_MODULE_RWX if ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UACCESS_FLUSHCACHE select ARCH_HAS_UACCESS_FLUSHCACHE
select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAS_UBSAN_SANITIZE_ALL

3
arch/powerpc/mm/pgtable_32.c
View File

@ -148,6 +148,9 @@ void mark_rodata_ro(void)
{ {
unsigned long numpages; unsigned long numpages;
if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX) && mmu_has_feature(MMU_FTR_HPTE_TABLE))
pr_warn("This platform has HASH MMU, STRICT_MODULE_RWX won't work\n");
if (v_block_mapped((unsigned long)_stext + 1)) { if (v_block_mapped((unsigned long)_stext + 1)) {
mmu_mark_rodata_ro(); mmu_mark_rodata_ro();
ptdump_check_wx(); ptdump_check_wx();