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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>
Subject: [PATCH v6 2/6] arm64: kernel: move identity map out of .text mapping
Date: Tue, 29 Nov 2022 17:14:14 +0100	[thread overview]
Message-ID: <20221129161418.1968319-3-ardb@kernel.org> (raw)
In-Reply-To: <20221129161418.1968319-1-ardb@kernel.org>

Reorganize the ID map slightly so that only code that is executed with
the MMU off or via the 1:1 mapping remains. This allows us to move the
identity map out of the .text segment, as it will no longer need
executable permissions via the kernel mapping.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/kernel/head.S        | 28 +++++++++++---------
 arch/arm64/kernel/vmlinux.lds.S |  2 +-
 arch/arm64/mm/proc.S            |  2 --
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index c4e12d466a5f35f0..bec97aad092c2b43 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -543,19 +543,6 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)
 	eret
 SYM_FUNC_END(init_kernel_el)
 
-/*
- * Sets the __boot_cpu_mode flag depending on the CPU boot mode passed
- * in w0. See arch/arm64/include/asm/virt.h for more info.
- */
-SYM_FUNC_START_LOCAL(set_cpu_boot_mode_flag)
-	adr_l	x1, __boot_cpu_mode
-	cmp	w0, #BOOT_CPU_MODE_EL2
-	b.ne	1f
-	add	x1, x1, #4
-1:	str	w0, [x1]			// Save CPU boot mode
-	ret
-SYM_FUNC_END(set_cpu_boot_mode_flag)
-
 	/*
 	 * This provides a "holding pen" for platforms to hold all secondary
 	 * cores are held until we're ready for them to initialise.
@@ -599,6 +586,7 @@ SYM_FUNC_START_LOCAL(secondary_startup)
 	br	x8
 SYM_FUNC_END(secondary_startup)
 
+	.text
 SYM_FUNC_START_LOCAL(__secondary_switched)
 	mov	x0, x20
 	bl	set_cpu_boot_mode_flag
@@ -631,6 +619,19 @@ SYM_FUNC_START_LOCAL(__secondary_too_slow)
 	b	__secondary_too_slow
 SYM_FUNC_END(__secondary_too_slow)
 
+/*
+ * Sets the __boot_cpu_mode flag depending on the CPU boot mode passed
+ * in w0. See arch/arm64/include/asm/virt.h for more info.
+ */
+SYM_FUNC_START_LOCAL(set_cpu_boot_mode_flag)
+	adr_l	x1, __boot_cpu_mode
+	cmp	w0, #BOOT_CPU_MODE_EL2
+	b.ne	1f
+	add	x1, x1, #4
+1:	str	w0, [x1]			// Save CPU boot mode
+	ret
+SYM_FUNC_END(set_cpu_boot_mode_flag)
+
 /*
  * The booting CPU updates the failed status @__early_cpu_boot_status,
  * with MMU turned off.
@@ -662,6 +663,7 @@ SYM_FUNC_END(__secondary_too_slow)
  * Checks if the selected granule size is supported by the CPU.
  * If it isn't, park the CPU
  */
+	.section ".idmap.text","awx"
 SYM_FUNC_START(__enable_mmu)
 	mrs	x3, ID_AA64MMFR0_EL1
 	ubfx	x3, x3, #ID_AA64MMFR0_EL1_TGRAN_SHIFT, 4
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 4c13dafc98b8400f..407415a5163ab62f 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -179,7 +179,6 @@ SECTIONS
 			LOCK_TEXT
 			KPROBES_TEXT
 			HYPERVISOR_TEXT
-			IDMAP_TEXT
 			*(.gnu.warning)
 		. = ALIGN(16);
 		*(.got)			/* Global offset table		*/
@@ -206,6 +205,7 @@ SECTIONS
 		TRAMP_TEXT
 		HIBERNATE_TEXT
 		KEXEC_TEXT
+		IDMAP_TEXT
 		. = ALIGN(PAGE_SIZE);
 	}
 
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 066fa60b93d24827..91410f48809000a0 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -110,7 +110,6 @@ SYM_FUNC_END(cpu_do_suspend)
  *
  * x0: Address of context pointer
  */
-	.pushsection ".idmap.text", "awx"
 SYM_FUNC_START(cpu_do_resume)
 	ldp	x2, x3, [x0]
 	ldp	x4, x5, [x0, #16]
@@ -166,7 +165,6 @@ alternative_else_nop_endif
 	isb
 	ret
 SYM_FUNC_END(cpu_do_resume)
-	.popsection
 #endif
 
 	.pushsection ".idmap.text", "awx"
-- 
2.35.1


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  parent reply	other threads:[~2022-11-29 16:18 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-29 16:14 [PATCH v6 0/6] arm64: Permit EFI boot with MMU and caches on Ard Biesheuvel
2022-11-29 16:14 ` [PATCH v6 1/6] arm64: head: Move all finalise_el2 calls to after __enable_mmu Ard Biesheuvel
2022-11-29 16:14 ` Ard Biesheuvel [this message]
2022-11-29 16:14 ` [PATCH v6 3/6] arm64: head: record the MMU state at primary entry Ard Biesheuvel
2022-12-01  9:18   ` Ard Biesheuvel
2022-12-01 17:51     ` Will Deacon
2022-11-29 16:14 ` [PATCH v6 4/6] arm64: head: avoid cache invalidation when entering with the MMU on Ard Biesheuvel
2022-11-29 16:14 ` [PATCH v6 5/6] arm64: head: Clean the ID map and the HYP text to the PoC if needed Ard Biesheuvel
2022-11-29 16:14 ` [PATCH v6 6/6] arm64: lds: reduce effective minimum image alignment to 64k Ard Biesheuvel

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