Subject: [PATCH v6 06/18] arm64: ptrauth: Add bootup/runtime flags for __cpu_setup

From: Amit Daniel Kachhap <[email-masked]>
Date: Fri, 6 Mar 2020 12:05:13 +0530

This patch allows __cpu_setup to be invoked with one of these flags,
ARM64_CPU_BOOT_PRIMARY, ARM64_CPU_BOOT_SECONDARY or ARM64_CPU_RUNTIME.
This is required as some cpufeatures need different handling during
different scenarios.

The input parameter in x0 is preserved till the end to be used inside
this function.

There should be no functional change with this patch and is useful
for the subsequent ptrauth patch which utilizes it. Some upcoming
arm cpufeatures can also utilize these flags.

Suggested-by: James Morse <[email-masked]>
Reviewed-by: Suzuki K Poulose <[email-masked]>
Signed-off-by: Amit Daniel Kachhap <[email-masked]>
---
 arch/arm64/include/asm/smp.h |  5 +++++
 arch/arm64/kernel/head.S     |  2 ++
 arch/arm64/kernel/sleep.S    |  2 ++
 arch/arm64/mm/proc.S         | 26 +++++++++++++++-----------
 4 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index a0c8a0b..8159000 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -23,6 +23,11 @@
 #define CPU_STUCK_REASON_52_BIT_VA	(UL(1) << CPU_STUCK_REASON_SHIFT)
 #define CPU_STUCK_REASON_NO_GRAN	(UL(2) << CPU_STUCK_REASON_SHIFT)
 
+/* Options for __cpu_setup */
+#define ARM64_CPU_BOOT_PRIMARY		(1)
+#define ARM64_CPU_BOOT_SECONDARY	(2)
+#define ARM64_CPU_RUNTIME		(3)
+
 #ifndef __ASSEMBLY__
 
 #include <asm/percpu.h>
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 3d18163..5a7ce15 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -118,6 +118,7 @@ ENTRY(stext)
 	 * On return, the CPU will be ready for the MMU to be turned on and
 	 * the TCR will have been set.
 	 */
+	mov	x0, #ARM64_CPU_BOOT_PRIMARY
 	bl	__cpu_setup			// initialise processor
 	b	__primary_switch
 ENDPROC(stext)
@@ -712,6 +713,7 @@ secondary_startup:
 	 * Common entry point for secondary CPUs.
 	 */
 	bl	__cpu_secondary_check52bitva
+	mov	x0, #ARM64_CPU_BOOT_SECONDARY
 	bl	__cpu_setup			// initialise processor
 	adrp	x1, swapper_pg_dir
 	bl	__enable_mmu
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index f5b04dd..7b2f2e6 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -3,6 +3,7 @@
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/assembler.h>
+#include <asm/smp.h>
 
 	.text
 /*
@@ -99,6 +100,7 @@ ENDPROC(__cpu_suspend_enter)
 	.pushsection ".idmap.text", "awx"
 ENTRY(cpu_resume)
 	bl	el2_setup		// if in EL2 drop to EL1 cleanly
+	mov	x0, #ARM64_CPU_RUNTIME
 	bl	__cpu_setup
 	/* enable the MMU early - so we can access sleep_save_stash by va */
 	adrp	x1, swapper_pg_dir
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index aafed69..ea0db17 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -408,31 +408,31 @@ SYM_FUNC_END(idmap_kpti_install_ng_mappings)
 /*
  *	__cpu_setup
  *
- *	Initialise the processor for turning the MMU on.  Return in x0 the
- *	value of the SCTLR_EL1 register.
+ *	Initialise the processor for turning the MMU on.
+ *
+ * Input:
+ *	x0 with a flag ARM64_CPU_BOOT_PRIMARY/ARM64_CPU_BOOT_SECONDARY/ARM64_CPU_RUNTIME.
+ * Output:
+ *	Return in x0 the value of the SCTLR_EL1 register.
  */
 	.pushsection ".idmap.text", "awx"
 SYM_FUNC_START(__cpu_setup)
 	tlbi	vmalle1				// Invalidate local TLB
 	dsb	nsh
 
-	mov	x0, #3 << 20
-	msr	cpacr_el1, x0			// Enable FP/ASIMD
-	mov	x0, #1 << 12			// Reset mdscr_el1 and disable
-	msr	mdscr_el1, x0			// access to the DCC from EL0
+	mov	x1, #3 << 20
+	msr	cpacr_el1, x1			// Enable FP/ASIMD
+	mov	x1, #1 << 12			// Reset mdscr_el1 and disable
+	msr	mdscr_el1, x1			// access to the DCC from EL0
 	isb					// Unmask debug exceptions now,
 	enable_dbg				// since this is per-cpu
-	reset_pmuserenr_el0 x0			// Disable PMU access from EL0
+	reset_pmuserenr_el0 x1			// Disable PMU access from EL0
 	/*
 	 * Memory region attributes
 	 */
 	mov_q	x5, MAIR_EL1_SET
 	msr	mair_el1, x5
 	/*
-	 * Prepare SCTLR
-	 */
-	mov_q	x0, SCTLR_EL1_SET
-	/*
 	 * Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
 	 * both user and kernel.
 	 */
@@ -468,5 +468,9 @@ SYM_FUNC_START(__cpu_setup)
 1:
 #endif	/* CONFIG_ARM64_HW_AFDBM */
 	msr	tcr_el1, x10
+	/*
+	 * Prepare SCTLR
+	 */
+	mov_q	x0, SCTLR_EL1_SET
 	ret					// return to head.S
 SYM_FUNC_END(__cpu_setup)
-- 
2.7.4

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