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

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Date:   Fri, 19 Jun 2020 15:06:57 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v1 6/8] powerpc/32s: Only leave NX unset on segments used for
 modules

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@...roup.eu>
---
 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