linux-kernel - [PATCH 1/2] LoongArch: Initialise unused Direct Map Windows

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Date: Thu, 13 Jun 2024 17:41:34 +0100
From: Jiaxun Yang <jiaxun.yang@...goat.com>
To: Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>
Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org, 
 Jiaxun Yang <jiaxun.yang@...goat.com>, stable@...r.kernel.org
Subject: [PATCH 1/2] LoongArch: Initialise unused Direct Map Windows

DMW 2 & 3 are unused by kernel, however firmware may leave
garbage in them and interfere kernel's address mapping.

Clear them as necessary.

Cc: stable@...r.kernel.org
Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
---
 arch/loongarch/include/asm/loongarch.h   |  4 ++++
 arch/loongarch/include/asm/stackframe.h  | 11 +++++++++++
 arch/loongarch/kernel/head.S             | 12 ++----------
 arch/loongarch/power/suspend_asm.S       |  6 +-----
 drivers/firmware/efi/libstub/loongarch.c |  2 ++
 5 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
index eb09adda54b7..3720096efcf9 100644
--- a/arch/loongarch/include/asm/loongarch.h
+++ b/arch/loongarch/include/asm/loongarch.h
@@ -889,6 +889,10 @@
 #define CSR_DMW1_BASE		(CSR_DMW1_VSEG << DMW_PABITS)
 #define CSR_DMW1_INIT		(CSR_DMW1_BASE | CSR_DMW1_MAT | CSR_DMW1_PLV0)
 
+/* Direct Map window 2/3 - unused */
+#define CSR_DMW2_INIT		0
+#define CSR_DMW3_INIT		0
+
 /* Performance Counter registers */
 #define LOONGARCH_CSR_PERFCTRL0		0x200	/* 32 perf event 0 config */
 #define LOONGARCH_CSR_PERFCNTR0		0x201	/* 64 perf event 0 count value */
diff --git a/arch/loongarch/include/asm/stackframe.h b/arch/loongarch/include/asm/stackframe.h
index d9eafd3ee3d1..10c5dcf56bc7 100644
--- a/arch/loongarch/include/asm/stackframe.h
+++ b/arch/loongarch/include/asm/stackframe.h
@@ -38,6 +38,17 @@
 	cfi_restore \reg \offset \docfi
 	.endm
 
+	.macro SETUP_DMWS temp1
+	li.d	\temp1, CSR_DMW0_INIT
+	csrwr	\temp1, LOONGARCH_CSR_DMWIN0
+	li.d	\temp1, CSR_DMW1_INIT
+	csrwr	\temp1, LOONGARCH_CSR_DMWIN1
+	li.d	\temp1, CSR_DMW2_INIT
+	csrwr	\temp1, LOONGARCH_CSR_DMWIN2
+	li.d	\temp1, CSR_DMW3_INIT
+	csrwr	\temp1, LOONGARCH_CSR_DMWIN3
+	.endm
+
 /* Jump to the runtime virtual address. */
 	.macro JUMP_VIRT_ADDR temp1 temp2
 	li.d	\temp1, CACHE_BASE
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index 4677ea8fa8e9..1a71fc09bfd6 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -44,11 +44,7 @@ SYM_DATA(kernel_fsize, .long _kernel_fsize);
 SYM_CODE_START(kernel_entry)			# kernel entry point
 
 	/* Config direct window and set PG */
-	li.d		t0, CSR_DMW0_INIT	# UC, PLV0, 0x8000 xxxx xxxx xxxx
-	csrwr		t0, LOONGARCH_CSR_DMWIN0
-	li.d		t0, CSR_DMW1_INIT	# CA, PLV0, 0x9000 xxxx xxxx xxxx
-	csrwr		t0, LOONGARCH_CSR_DMWIN1
-
+	SETUP_DMWS	t0
 	JUMP_VIRT_ADDR	t0, t1
 
 	/* Enable PG */
@@ -124,11 +120,7 @@ SYM_CODE_END(kernel_entry)
  * function after setting up the stack and tp registers.
  */
 SYM_CODE_START(smpboot_entry)
-	li.d		t0, CSR_DMW0_INIT	# UC, PLV0
-	csrwr		t0, LOONGARCH_CSR_DMWIN0
-	li.d		t0, CSR_DMW1_INIT	# CA, PLV0
-	csrwr		t0, LOONGARCH_CSR_DMWIN1
-
+	SETUP_DMWS	t0
 	JUMP_VIRT_ADDR	t0, t1
 
 #ifdef CONFIG_PAGE_SIZE_4KB
diff --git a/arch/loongarch/power/suspend_asm.S b/arch/loongarch/power/suspend_asm.S
index e2fc3b4e31f0..6fdd74eb219b 100644
--- a/arch/loongarch/power/suspend_asm.S
+++ b/arch/loongarch/power/suspend_asm.S
@@ -73,11 +73,7 @@ SYM_FUNC_START(loongarch_suspend_enter)
 	 * Reload all of the registers and return.
 	 */
 SYM_INNER_LABEL(loongarch_wakeup_start, SYM_L_GLOBAL)
-	li.d		t0, CSR_DMW0_INIT	# UC, PLV0
-	csrwr		t0, LOONGARCH_CSR_DMWIN0
-	li.d		t0, CSR_DMW1_INIT	# CA, PLV0
-	csrwr		t0, LOONGARCH_CSR_DMWIN1
-
+	SETUP_DMWS	t0
 	JUMP_VIRT_ADDR	t0, t1
 
 	/* Enable PG */
diff --git a/drivers/firmware/efi/libstub/loongarch.c b/drivers/firmware/efi/libstub/loongarch.c
index d0ef93551c44..3782d0a187d1 100644
--- a/drivers/firmware/efi/libstub/loongarch.c
+++ b/drivers/firmware/efi/libstub/loongarch.c
@@ -74,6 +74,8 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
 	/* Config Direct Mapping */
 	csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
 	csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
+	csr_write64(CSR_DMW2_INIT, LOONGARCH_CSR_DMWIN2);
+	csr_write64(CSR_DMW3_INIT, LOONGARCH_CSR_DMWIN3);
 
 	real_kernel_entry = (void *)kernel_entry_address(kernel_addr, image);
 

-- 
2.43.0