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Date:   Fri, 18 Oct 2019 09:10:28 -0700
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Subject: [PATCH 13/18] arm64: preserve x18 when CPU is suspended
From:   Sami Tolvanen <samitolvanen@google.com>
To:     Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc:     Dave Martin <Dave.Martin@arm.com>,
        Kees Cook <keescook@chromium.org>,
        Laura Abbott <labbott@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        clang-built-linux@googlegroups.com,
        kernel-hardening@lists.openwall.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Sami Tolvanen <samitolvanen@google.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Don't lose the current task's shadow stack when the CPU is suspended.

Signed-off-by: Sami Tolvanen <samitolvanen@google.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