From e5fd91f1ef340da553f7a79da9540c3db711c937 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?=
 <emulatorman@parabola.nu>
Date: Tue, 8 Sep 2015 01:01:14 -0300
Subject: Linux-libre 4.2-gnu

---
 arch/arm64/kernel/entry.S | 45 +++++++++++++++++++++++++++------------------
 1 file changed, 27 insertions(+), 18 deletions(-)

(limited to 'arch/arm64/kernel/entry.S')

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index bddd04d03..e16351819 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -21,7 +21,7 @@
 #include <linux/init.h>
 #include <linux/linkage.h>
 
-#include <asm/alternative-asm.h>
+#include <asm/alternative.h>
 #include <asm/assembler.h>
 #include <asm/asm-offsets.h>
 #include <asm/cpufeature.h>
@@ -124,21 +124,24 @@
 	msr	sp_el0, x23
 
 #ifdef CONFIG_ARM64_ERRATUM_845719
-	alternative_insn						\
-	"nop",								\
-	"tbz x22, #4, 1f",						\
-	ARM64_WORKAROUND_845719
+
+#undef SEQUENCE_ORG
+#undef SEQUENCE_ALT
+
 #ifdef CONFIG_PID_IN_CONTEXTIDR
-	alternative_insn						\
-	"nop; nop",							\
-	"mrs x29, contextidr_el1; msr contextidr_el1, x29; 1:",		\
-	ARM64_WORKAROUND_845719
+
+#define SEQUENCE_ORG	"nop ; nop ; nop"
+#define SEQUENCE_ALT	"tbz x22, #4, 1f ; mrs x29, contextidr_el1; msr contextidr_el1, x29; 1:"
+
 #else
-	alternative_insn						\
-	"nop",								\
-	"msr contextidr_el1, xzr; 1:",					\
-	ARM64_WORKAROUND_845719
+
+#define SEQUENCE_ORG	"nop ; nop"
+#define SEQUENCE_ALT	"tbz x22, #4, 1f ; msr contextidr_el1, xzr; 1:"
+
 #endif
+
+	alternative_insn SEQUENCE_ORG, SEQUENCE_ALT, ARM64_WORKAROUND_845719
+
 #endif
 	.endif
 	msr	elr_el1, x21			// set up the return data
@@ -349,8 +352,8 @@ el1_inv:
 	// TODO: add support for undefined instructions in kernel mode
 	enable_dbg
 	mov	x0, sp
+	mov	x2, x1
 	mov	x1, #BAD_SYNC
-	mrs	x2, esr_el1
 	b	bad_mode
 ENDPROC(el1_sync)
 
@@ -550,7 +553,7 @@ el0_inv:
 	ct_user_exit
 	mov	x0, sp
 	mov	x1, #BAD_SYNC
-	mrs	x2, esr_el1
+	mov	x2, x25
 	bl	bad_mode
 	b	ret_to_user
 ENDPROC(el0_sync)
@@ -582,7 +585,8 @@ ENDPROC(el0_irq)
  *
  */
 ENTRY(cpu_switch_to)
-	add	x8, x0, #THREAD_CPU_CONTEXT
+	mov	x10, #THREAD_CPU_CONTEXT
+	add	x8, x0, x10
 	mov	x9, sp
 	stp	x19, x20, [x8], #16		// store callee-saved registers
 	stp	x21, x22, [x8], #16
@@ -591,7 +595,7 @@ ENTRY(cpu_switch_to)
 	stp	x27, x28, [x8], #16
 	stp	x29, x9, [x8], #16
 	str	lr, [x8]
-	add	x8, x1, #THREAD_CPU_CONTEXT
+	add	x8, x1, x10
 	ldp	x19, x20, [x8], #16		// restore callee-saved registers
 	ldp	x21, x22, [x8], #16
 	ldp	x23, x24, [x8], #16
@@ -609,11 +613,16 @@ ENDPROC(cpu_switch_to)
  */
 ret_fast_syscall:
 	disable_irq				// disable interrupts
-	ldr	x1, [tsk, #TI_FLAGS]
+	ldr	x1, [tsk, #TI_FLAGS]		// re-check for syscall tracing
+	and	x2, x1, #_TIF_SYSCALL_WORK
+	cbnz	x2, ret_fast_syscall_trace
 	and	x2, x1, #_TIF_WORK_MASK
 	cbnz	x2, fast_work_pending
 	enable_step_tsk x1, x2
 	kernel_exit 0, ret = 1
+ret_fast_syscall_trace:
+	enable_irq				// enable interrupts
+	b	__sys_trace_return
 
 /*
  * Ok, we need to do extra processing, enter the slow path.
-- 
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