diff mbox series

[v2,12/17] arm64: preserve x18 when CPU is suspended

Message ID 20191024225132.13410-13-samitolvanen@google.com (mailing list archive)
State New, archived
Headers show
Series [v2,01/17] arm64: mm: don't use x18 in idmap_kpti_install_ng_mappings | expand

Commit Message

Sami Tolvanen Oct. 24, 2019, 10:51 p.m. UTC 
Don't lose the current task's shadow stack when the CPU is suspended.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 arch/arm64/include/asm/suspend.h | 2 +-
 arch/arm64/mm/proc.S             | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h
index 8939c87c4dce..0cde2f473971 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 12
+#define NR_CTX_REGS 13
 #define NR_CALLEE_SAVED_REGS 12
 
 /*
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index fdabf40a83c8..0e7c353c9dfd 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -49,6 +49,8 @@ 
  * cpu_do_suspend - save CPU registers context
  *
  * x0: virtual address of context pointer
+ *
+ * This must be kept in sync with struct cpu_suspend_ctx in <asm/suspend.h>.
  */
 ENTRY(cpu_do_suspend)
 	mrs	x2, tpidr_el0
@@ -73,6 +75,9 @@  alternative_endif
 	stp	x8, x9, [x0, #48]
 	stp	x10, x11, [x0, #64]
 	stp	x12, x13, [x0, #80]
+#ifdef CONFIG_SHADOW_CALL_STACK
+	str	x18, [x0, #96]
+#endif
 	ret
 ENDPROC(cpu_do_suspend)
 
@@ -89,6 +94,10 @@  ENTRY(cpu_do_resume)
 	ldp	x9, x10, [x0, #48]
 	ldp	x11, x12, [x0, #64]
 	ldp	x13, x14, [x0, #80]
+#ifdef CONFIG_SHADOW_CALL_STACK
+	ldr	x18, [x0, #96]
+	str	xzr, [x0, #96]
+#endif
 	msr	tpidr_el0, x2
 	msr	tpidrro_el0, x3
 	msr	contextidr_el1, x4