linux-kernel - [PATCH v9 15/18] arm64: kexec: kexec EL2 vectors

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Date:   Wed, 25 Mar 2020 23:24:17 -0400
From:   Pavel Tatashin <pasha.tatashin@...een.com>
To:     pasha.tatashin@...een.com, jmorris@...ei.org, sashal@...nel.org,
        ebiederm@...ssion.com, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org, corbet@....net,
        catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, maz@...nel.org,
        james.morse@....com, vladimir.murzin@....com,
        matthias.bgg@...il.com, bhsharma@...hat.com, linux-mm@...ck.org,
        mark.rutland@....com, steve.capper@....com, rfontana@...hat.com,
        tglx@...utronix.de, selindag@...il.com
Subject: [PATCH v9 15/18] arm64: kexec: kexec EL2 vectors

If we have a EL2 mode without VHE, the EL2 vectors are needed in order
to switch to EL2 and jump to new world with hyperivsor privileges.

Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
---
 arch/arm64/include/asm/kexec.h      |  5 +++++
 arch/arm64/kernel/asm-offsets.c     |  1 +
 arch/arm64/kernel/machine_kexec.c   |  5 +++++
 arch/arm64/kernel/relocate_kernel.S | 35 +++++++++++++++++++++++++++++
 4 files changed, 46 insertions(+)

diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index d944c2e289b2..0f758fd51518 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -95,6 +95,7 @@ static inline void crash_post_resume(void) {}
 extern const unsigned long kexec_relocate_code_size;
 extern const unsigned char kexec_relocate_code_start[];
 extern const unsigned long kexec_kern_reloc_offset;
+extern const unsigned long kexec_el2_vectors_offset;
 #endif
 
 /*
@@ -104,6 +105,9 @@ extern const unsigned long kexec_kern_reloc_offset;
  *		kernel, or purgatory entry address).
  * kern_arg0	first argument to kernel is its dtb address. The other
  *		arguments are currently unused, and must be set to 0
+ * el2_vector	If present means that relocation routine will go to EL1
+ *		from EL2 to do the copy, and then back to EL2 to do the jump
+ *		to new world.
  */
 struct kern_reloc_arg {
 	phys_addr_t head;
@@ -112,6 +116,7 @@ struct kern_reloc_arg {
 	phys_addr_t kern_arg1;
 	phys_addr_t kern_arg2;
 	phys_addr_t kern_arg3;
+	phys_addr_t el2_vector;
 };
 
 #define ARCH_HAS_KIMAGE_ARCH
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 448230684749..ff974b648347 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -136,6 +136,7 @@ int main(void)
   DEFINE(KEXEC_KRELOC_KERN_ARG1,	offsetof(struct kern_reloc_arg, kern_arg1));
   DEFINE(KEXEC_KRELOC_KERN_ARG2,	offsetof(struct kern_reloc_arg, kern_arg2));
   DEFINE(KEXEC_KRELOC_KERN_ARG3,	offsetof(struct kern_reloc_arg, kern_arg3));
+  DEFINE(KEXEC_KRELOC_EL2_VECTOR,	offsetof(struct kern_reloc_arg, el2_vector));
 #endif
   return 0;
 }
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index ab571fca9bd1..bd398def7627 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -84,6 +84,11 @@ int machine_kexec_post_load(struct kimage *kimage)
 	kern_reloc_arg->head = kimage->head;
 	kern_reloc_arg->entry_addr = kimage->start;
 	kern_reloc_arg->kern_arg0 = kimage->arch.dtb_mem;
+	/* Setup vector table only when EL2 is available, but no VHE */
+	if (is_hyp_mode_available() && !is_kernel_in_hyp_mode()) {
+		kern_reloc_arg->el2_vector = __pa(reloc_code)
+						+ kexec_el2_vectors_offset;
+	}
 	kexec_image_info(kimage);
 
 	return 0;
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index aa9f2b2cd77c..6fd2fc0ef373 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -89,6 +89,38 @@ ENTRY(arm64_relocate_new_kernel)
 .ltorg
 END(arm64_relocate_new_kernel)
 
+.macro el1_sync_64
+	br	x4			/* Jump to new world from el2 */
+	.fill 31, 4, 0			/* Set other 31 instr to zeroes */
+.endm
+
+.macro invalid_vector label
+\label:
+	b \label
+	.fill 31, 4, 0			/* Set other 31 instr to zeroes */
+.endm
+
+/* el2 vectors - switch el2 here while we restore the memory image. */
+	.align 11
+ENTRY(kexec_el2_vectors)
+	invalid_vector el2_sync_invalid_sp0	/* Synchronous EL2t */
+	invalid_vector el2_irq_invalid_sp0	/* IRQ EL2t */
+	invalid_vector el2_fiq_invalid_sp0	/* FIQ EL2t */
+	invalid_vector el2_error_invalid_sp0	/* Error EL2t */
+	invalid_vector el2_sync_invalid_spx	/* Synchronous EL2h */
+	invalid_vector el2_irq_invalid_spx	/* IRQ EL2h */
+	invalid_vector el2_fiq_invalid_spx	/* FIQ EL2h */
+	invalid_vector el2_error_invalid_spx	/* Error EL2h */
+		el1_sync_64			/* Synchronous 64-bit EL1 */
+	invalid_vector el1_irq_invalid_64	/* IRQ 64-bit EL1 */
+	invalid_vector el1_fiq_invalid_64	/* FIQ 64-bit EL1 */
+	invalid_vector el1_error_invalid_64	/* Error 64-bit EL1 */
+	invalid_vector el1_sync_invalid_32	/* Synchronous 32-bit EL1 */
+	invalid_vector el1_irq_invalid_32	/* IRQ 32-bit EL1 */
+	invalid_vector el1_fiq_invalid_32	/* FIQ 32-bit EL1 */
+	invalid_vector el1_error_invalid_32	/* Error 32-bit EL1 */
+END(kexec_el2_vectors)
+
 .Lkexec_relocate_code_end:
 .org	KEXEC_CONTROL_PAGE_SIZE
 .align 3	/* To keep the 64-bit values below naturally aligned. */
@@ -102,3 +134,6 @@ kexec_relocate_code_size:
 .globl kexec_kern_reloc_offset
 kexec_kern_reloc_offset:
 	.quad	arm64_relocate_new_kernel - kexec_relocate_code_start
+.globl kexec_el2_vectors_offset
+kexec_el2_vectors_offset:
+	.quad	kexec_el2_vectors - kexec_relocate_code_start
-- 
2.17.1