linux-kernel - [PATCH v1 45/46] powerpc/32s: Allow mapping with BATs with DEBUG

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Message-Id: <08f37b5315c5d8029c066d0ffecd3439003b18ae.1584360344.git.christophe.leroy@c-s.fr>
Date:   Mon, 16 Mar 2020 12:36:31 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
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 45/46] powerpc/32s: Allow mapping with BATs with
 DEBUG_PAGEALLOC

DEBUG_PAGEALLOC only manages RW data.

Text and RO data can still be mapped with BATs.

In order to map with BATs, also enforce data alignment. Set
by default to 256M which is a good compromise for keeping
enough BATs for also KASAN and IMMR.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/Kconfig           | 1 +
 arch/powerpc/mm/book3s32/mmu.c | 6 ++++++
 arch/powerpc/mm/init_32.c      | 5 ++---
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c086992573d3..44c490e05954 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -793,6 +793,7 @@ config DATA_SHIFT
 	range 17 28 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC) && PPC_BOOK3S_32
 	range 19 23 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC) && PPC_8xx
 	default 22 if STRICT_KERNEL_RWX && PPC_BOOK3S_32
+	default 18 if DEBUG_PAGEALLOC && PPC_BOOK3S_32
 	default 23 if STRICT_KERNEL_RWX && PPC_8xx
 	default 23 if DEBUG_PAGEALLOC && PPC_8xx && PIN_TLB_DATA
 	default 19 if DEBUG_PAGEALLOC && PPC_8xx
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index a9b2cbc74797..a6dcc708eee3 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -170,6 +170,12 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
 		pr_debug("RAM mapped without BATs\n");
 		return base;
 	}
+	if (debug_pagealloc_enabled()) {
+		if (base >= border)
+			return base;
+		if (top >= border)
+			top = border;
+	}
 
 	if (!strict_kernel_rwx_enabled() || base >= border || top <= border)
 		return __mmu_mapin_ram(base, top);
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 8977a7c2543d..36c39bd37256 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -99,10 +99,9 @@ static void __init MMU_setup(void)
 	if (IS_ENABLED(CONFIG_PPC_8xx))
 		return;
 
-	if (debug_pagealloc_enabled()) {
-		__map_without_bats = 1;
+	if (debug_pagealloc_enabled())
 		__map_without_ltlbs = 1;
-	}
+
 	if (strict_kernel_rwx_enabled())
 		__map_without_ltlbs = 1;
 }
-- 
2.25.0