From 72d5ed0cd9b7b89391596440f5b320dfda2aff33 Mon Sep 17 00:00:00 2001
From: James Morse <james.morse@arm.com>
Date: Mon, 28 Feb 2022 17:30:00 +0100
Subject: [PATCH 12/22] arm64: entry: Add macro for reading symbol addresses
 from the trampoline

Git-commit: b28a8eebe81c186fdb1a0078263b30576c8e1f42
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
Patch-mainline: Queued in a subsystem tree
References: bsc#1191580 CVE-2022-0001 CVE-2022-000 CVE-2022-23960


The trampoline code needs to use the address of symbols in the wider
kernel, e.g. vectors. PC-relative addressing wouldn't work as the
trampoline code doesn't run at the address the linker expected.

tramp_ventry uses a literal pool, unless CONFIG_RANDOMIZE_BASE is
set, in which case it uses the data page as a literal pool because
the data page can be unmapped when running in user-space, which is
required for CPUs vulnerable to meltdown.

Pull this logic out as a macro, instead of adding a third copy
of it.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
[ Removed SDEI for stable backport ]
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
 arch/arm64/kernel/entry.S | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index b02d149d30cda..20c90b65a3423 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -1097,6 +1097,15 @@ alternative_else_nop_endif
 	sub	\dst, \dst, PAGE_SIZE
 	.endm
 
+	.macro tramp_data_read_var	dst, var
+#ifdef CONFIG_RANDOMIZE_BASE
+	tramp_data_page		\dst
+	add	\dst, \dst, #:lo12:__entry_tramp_data_\var
+	ldr	\dst, [\dst]
+#else
+	ldr	\dst, =\var
+#endif
+	.endm
 
 #define BHB_MITIGATION_NONE	0
 #define BHB_MITIGATION_LOOP	1
@@ -1127,13 +1136,8 @@ alternative_else_nop_endif
 	b	.
 2:
 	tramp_map_kernel	x30
-#ifdef CONFIG_RANDOMIZE_BASE
-	tramp_data_page		x30
 alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003
-	ldr	x30, [x30]
-#else
-	ldr	x30, =vectors
-#endif
+	tramp_data_read_var	x30, vectors
 	prfm	plil1strm, [x30, #(1b - \vector_start)]
 	msr	vbar_el1, x30
 	isb
@@ -1213,7 +1217,12 @@ END(tramp_exit_compat)
 	.align PAGE_SHIFT
 	.globl	__entry_tramp_data_start
 __entry_tramp_data_start:
+__entry_tramp_data_vectors:
 	.quad	vectors
+#ifdef CONFIG_ARM_SDE_INTERFACE
+__entry_tramp_data___sdei_asm_trampoline_next_handler:
+	.quad	__sdei_asm_handler
+#endif /* CONFIG_ARM_SDE_INTERFACE */
 	.popsection				// .rodata
 #endif /* CONFIG_RANDOMIZE_BASE */
 #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
-- 
2.34.1