summaryrefslogtreecommitdiff
path: root/arch/powerpc/Kconfig
diff options
context:
space:
mode:
authorChristophe Leroy <christophe.leroy@csgroup.eu>2021-09-24 20:13:53 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2021-10-22 07:22:05 +0300
commitfdacae8a84024474afff234bdd1dbe19ad597a10 (patch)
treee58f741868d07dcc2d824d6b539a77f5a371b120 /arch/powerpc/Kconfig
parent63f501e07a8557bc8ab79d17ef76ae21df1e395d (diff)
downloadlinux-fdacae8a84024474afff234bdd1dbe19ad597a10.tar.xz
powerpc: Activate CONFIG_STRICT_KERNEL_RWX by default
CONFIG_STRICT_KERNEL_RWX should be set by default on every architectures (See https://github.com/KSPP/linux/issues/4) On PPC32 we have to find a compromise between performance and/or memory wasting and selection of strict_kernel_rwx, because it implies either smaller memory chunks or larger alignment between RO memory and RW memory. For instance the 8xx maps memory with 8M pages. So either the limit between RO and RW must be 8M aligned or it falls back or 512k pages which implies more pressure on the TLB. book3s/32 maps memory with BATs as much as possible. BATS can have any power-of-two size between 128k and 256M but we have only 4 to 8 BATs so the alignment must be good enough to allow efficient use of the BATs and avoid falling back on standard page mapping which would kill performance. So let's go one step forward and make it the default but still allow users to unset it when wanted. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/057c40164084bfc7d77c0b2ff78d95dbf6a2a21b.1632503622.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/Kconfig')
-rw-r--r--arch/powerpc/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 5d0586214662..e43e17987b92 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -149,6 +149,7 @@ config PPC
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
+ select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
select ARCH_STACKWALK
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_DEBUG_PAGEALLOC if PPC_BOOK3S || PPC_8xx || 40x