File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S
new file mode 100644
index 0000000..b6c8bb9
--- /dev/null
+++ b/arch/arm/kernel/entry-v7m.S
@@ -0,0 +1,148 @@
+/*
+ * linux/arch/arm/kernel/entry-v7m.S
+ *
+ * Copyright (C) 2008 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Low-level vector interface routines for the ARMv7-M architecture
+ */
+#include <asm/memory.h>
+#include <asm/glue.h>
+#include <asm/thread_notify.h>
+#include <asm/v7m.h>
+
+#include "entry-header.S"
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+#error "CONFIG_TRACE_IRQFLAGS not supported on the current ARMv7M implementation"
+#endif
+
+__invalid_entry:
+ v7m_exception_entry
+#ifdef CONFIG_PRINTK
+ adr r0, strerr
+ mrs r1, ipsr
+ mov r2, lr
+ bl printk
+#endif
+ mov r0, sp
+ bl show_regs
+1: b 1b
+ENDPROC(__invalid_entry)
+
+strerr: .asciz "\nUnhandled exception: IPSR = %08lx LR = %08lx\n"
+
+ .align 2
+__irq_entry:
+ v7m_exception_entry
+
+ @
+ @ Invoke the IRQ handler
+ @
+ mrs r0, ipsr
+ ldr r1, =V7M_xPSR_EXCEPTIONNO
+ and r0, r1
+ sub r0, #16
+ mov r1, sp
+ stmdb sp!, {lr}
+ @ routine called with r0 = irq number, r1 = struct pt_regs *
+ bl nvic_handle_irq
+
+ pop {lr}
+ @
+ @ Check for any pending work if returning to user
+ @
+ ldr r1, =BASEADDR_V7M_SCB
+ ldr r0, [r1, V7M_SCB_ICSR]
+ tst r0, V7M_SCB_ICSR_RETTOBASE
+ beq 2f
+
+ get_thread_info tsk
+ ldr r2, [tsk, #TI_FLAGS]
+ tst r2, #_TIF_WORK_MASK
+ beq 2f @ no work pending
+ mov r0, #V7M_SCB_ICSR_PENDSVSET
+ str r0, [r1, V7M_SCB_ICSR] @ raise PendSV
+
+2:
+ @ registers r0-r3 and r12 are automatically restored on exception
+ @ return. r4-r7 were not clobbered in v7m_exception_entry so for
+ @ correctness they don't need to be restored. So only r8-r11 must be
+ @ restored here. The easiest way to do so is to restore r0-r7, too.
+ ldmia sp!, {r0-r11}
+ add sp, #S_FRAME_SIZE-S_IP
+ cpsie i
+ bx lr
+ENDPROC(__irq_entry)
+
+__pendsv_entry:
+ v7m_exception_entry
+
+ ldr r1, =BASEADDR_V7M_SCB
+ mov r0, #V7M_SCB_ICSR_PENDSVCLR
+ str r0, [r1, V7M_SCB_ICSR] @ clear PendSV
+
+ @ execute the pending work, including reschedule
+ get_thread_info tsk
+ mov why, #0
+ b ret_to_user
+ENDPROC(__pendsv_entry)
+
+/*
+ * Register switch for ARMv7-M processors.
+ * r0 = previous task_struct, r1 = previous thread_info, r2 = next thread_info
+ * previous and next are guaranteed not to be the same.
+ */
+ENTRY(__switch_to)
+ .fnstart
+ .cantunwind
+ add ip, r1, #TI_CPU_SAVE
+ stmia ip!, {r4 - r11} @ Store most regs on stack
+ str sp, [ip], #4
+ str lr, [ip], #4
+ mov r5, r0
+ add r4, r2, #TI_CPU_SAVE
+ ldr r0, =thread_notify_head
+ mov r1, #THREAD_NOTIFY_SWITCH
+ bl atomic_notifier_call_chain
+ mov ip, r4
+ mov r0, r5
+ ldmia ip!, {r4 - r11} @ Load all regs saved previously
+ ldr sp, [ip]
+ ldr pc, [ip, #4]!
+ .fnend
+ENDPROC(__switch_to)
+
+ .data
+#if CONFIG_CPU_V7M_NUM_IRQ <= 112
+ .align 9
+#else
+ .align 10
+#endif
+
+/*
+ * Vector table (Natural alignment need to be ensured)
+ */
+ENTRY(vector_table)
+ .long 0 @ 0 - Reset stack pointer
+ .long __invalid_entry @ 1 - Reset
+ .long __invalid_entry @ 2 - NMI
+ .long __invalid_entry @ 3 - HardFault
+ .long __invalid_entry @ 4 - MemManage
+ .long __invalid_entry @ 5 - BusFault
+ .long __invalid_entry @ 6 - UsageFault
+ .long __invalid_entry @ 7 - Reserved
+ .long __invalid_entry @ 8 - Reserved
+ .long __invalid_entry @ 9 - Reserved
+ .long __invalid_entry @ 10 - Reserved
+ .long vector_swi @ 11 - SVCall
+ .long __invalid_entry @ 12 - Debug Monitor
+ .long __invalid_entry @ 13 - Reserved
+ .long __pendsv_entry @ 14 - PendSV
+ .long __invalid_entry @ 15 - SysTick
+ .rept CONFIG_CPU_V7M_NUM_IRQ
+ .long __irq_entry @ External Interrupts
+ .endr