[PATCH 1/2] arm64: suspend: Save POR_EL0 over suspend

[Mark Brown]

POR_EL0 is a live EL0 register on systems with S1POE but it is not saved
and restored by cpu_do_suspend()/cpu_do_resume(). This means that the task
that initiated suspend can return to userspace with an UNKNOWN value. Fix
this by saving and restoring the value over suspend.

This increases the size of struct cpu_suspend_ctx.

Fixes: bf83dae90fbc ("arm64: enable the Permission Overlay Extension for EL0")
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 arch/arm64/include/asm/suspend.h | 2 +-
 arch/arm64/mm/proc.S             | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h
index a5abf0615594..eb9ce315f146 100644
--- a/arch/arm64/include/asm/suspend.h
+++ b/arch/arm64/include/asm/suspend.h
@@ -2,7 +2,7 @@
 #ifndef __ASM_SUSPEND_H
 #define __ASM_SUSPEND_H
 
-#define NR_CTX_REGS 15
+#define NR_CTX_REGS 16
 #define NR_CALLEE_SAVED_REGS 12
 
 /*
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index b1516630904d..664ea9e3b9ad 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -117,6 +117,10 @@ alternative_else_nop_endif
 alternative_if ARM64_SME
 	mrs_s	x2, SYS_TPIDR2_EL0
 	str	x2, [x0, #112]
+alternative_else_nop_endif
+alternative_if ARM64_HAS_S1POE
+	mrs	x2, REG_POR_EL0
+	str	x2, [x0, #120]
 alternative_else_nop_endif
 	ret
 SYM_FUNC_END(cpu_do_suspend)
@@ -160,6 +164,10 @@ alternative_if ARM64_SME
 	ldr	x2, [x0, #112]
 	msr_s	SYS_TPIDR2_EL0, x2
 alternative_else_nop_endif
+alternative_if ARM64_HAS_S1POE
+	ldr	x2, [x0, #120]
+	msr	REG_POR_EL0, x2
+alternative_else_nop_endif
 
 	msr	sctlr_el1, x12
 	set_this_cpu_offset x13

-- 
2.47.3