[PATCH v1 6/8] powerpc/32s: Only leave NX unset on segments used for modules

From: Christophe Leroy
Date: Fri Jun 19 2020 - 12:09:40 EST


Instead of leaving NX unset on all segments above the start
of vmalloc space, only leave NX unset on segments used for
modules.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/mm/book3s32/mmu.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index 03b6ba54460e..c0162911f6cb 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -187,6 +187,17 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
return __mmu_mapin_ram(border, top);
}

+static bool is_module_segment(unsigned long addr)
+{
+ if (!IS_ENABLED(CONFIG_MODULES))
+ return false;
+ if (addr < ALIGN_DOWN(VMALLOC_START, SZ_256M))
+ return false;
+ if (addr >= ALIGN(VMALLOC_END, SZ_256M))
+ return false;
+ return true;
+}
+
void mmu_mark_initmem_nx(void)
{
int nb = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4;
@@ -223,9 +234,9 @@ void mmu_mark_initmem_nx(void)

for (i = TASK_SIZE >> 28; i < 16; i++) {
/* Do not set NX on VM space for modules */
- if (IS_ENABLED(CONFIG_MODULES) &&
- (VMALLOC_START & 0xf0000000) == i << 28)
- break;
+ if (is_module_segment(i << 28))
+ continue;
+
mtsrin(mfsrin(i << 28) | 0x10000000, i << 28);
}
}
--
2.25.0