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Date: Fri, 18 Oct 2019 09:10:28 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Will Deacon <will@...nel.org>, Catalin Marinas <catalin.marinas@....com>, 
	Steven Rostedt <rostedt@...dmis.org>, Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Dave Martin <Dave.Martin@....com>, Kees Cook <keescook@...omium.org>, 
	Laura Abbott <labbott@...hat.com>, Mark Rutland <mark.rutland@....com>, 
	Nick Desaulniers <ndesaulniers@...gle.com>, clang-built-linux@...glegroups.com, 
	kernel-hardening@...ts.openwall.com, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH 13/18] arm64: preserve x18 when CPU is suspended

Don't lose the current task's shadow stack when the CPU is suspended.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
 arch/arm64/mm/proc.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index fdabf40a83c8..9a8bd4bc8549 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -73,6 +73,9 @@ alternative_endif
 	stp	x8, x9, [x0, #48]
 	stp	x10, x11, [x0, #64]
 	stp	x12, x13, [x0, #80]
+#ifdef CONFIG_SHADOW_CALL_STACK
+	stp	x18, xzr, [x0, #96]
+#endif
 	ret
 ENDPROC(cpu_do_suspend)
 
@@ -89,6 +92,9 @@ ENTRY(cpu_do_resume)
 	ldp	x9, x10, [x0, #48]
 	ldp	x11, x12, [x0, #64]
 	ldp	x13, x14, [x0, #80]
+#ifdef CONFIG_SHADOW_CALL_STACK
+	ldp	x18, x19, [x0, #96]
+#endif
 	msr	tpidr_el0, x2
 	msr	tpidrro_el0, x3
 	msr	contextidr_el1, x4
-- 
2.23.0.866.gb869b98d4c-goog

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