v4.19.13 snapshot.
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
new file mode 100644
index 0000000..7734248
--- /dev/null
+++ b/arch/arm/kernel/entry-header.S
@@ -0,0 +1,419 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/init.h>
+#include <linux/linkage.h>
+
+#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
+#include <asm/errno.h>
+#include <asm/thread_info.h>
+#include <asm/v7m.h>
+
+@ Bad Abort numbers
+@ -----------------
+@
+#define BAD_PREFETCH 0
+#define BAD_DATA 1
+#define BAD_ADDREXCPTN 2
+#define BAD_IRQ 3
+#define BAD_UNDEFINSTR 4
+
+@
+@ Most of the stack format comes from struct pt_regs, but with
+@ the addition of 8 bytes for storing syscall args 5 and 6.
+@ This _must_ remain a multiple of 8 for EABI.
+@
+#define S_OFF 8
+
+/*
+ * The SWI code relies on the fact that R0 is at the bottom of the stack
+ * (due to slow/fast restore user regs).
+ */
+#if S_R0 != 0
+#error "Please fix"
+#endif
+
+ .macro zero_fp
+#ifdef CONFIG_FRAME_POINTER
+ mov fp, #0
+#endif
+ .endm
+
+#ifdef CONFIG_ALIGNMENT_TRAP
+#define ATRAP(x...) x
+#else
+#define ATRAP(x...)
+#endif
+
+ .macro alignment_trap, rtmp1, rtmp2, label
+#ifdef CONFIG_ALIGNMENT_TRAP
+ mrc p15, 0, \rtmp2, c1, c0, 0
+ ldr \rtmp1, \label
+ ldr \rtmp1, [\rtmp1]
+ teq \rtmp1, \rtmp2
+ mcrne p15, 0, \rtmp1, c1, c0, 0
+#endif
+ .endm
+
+#ifdef CONFIG_CPU_V7M
+/*
+ * ARMv7-M exception entry/exit macros.
+ *
+ * xPSR, ReturnAddress(), LR (R14), R12, R3, R2, R1, and R0 are
+ * automatically saved on the current stack (32 words) before
+ * switching to the exception stack (SP_main).
+ *
+ * If exception is taken while in user mode, SP_main is
+ * empty. Otherwise, SP_main is aligned to 64 bit automatically
+ * (CCR.STKALIGN set).
+ *
+ * Linux assumes that the interrupts are disabled when entering an
+ * exception handler and it may BUG if this is not the case. Interrupts
+ * are disabled during entry and reenabled in the exit macro.
+ *
+ * v7m_exception_slow_exit is used when returning from SVC or PendSV.
+ * When returning to kernel mode, we don't return from exception.
+ */
+ .macro v7m_exception_entry
+ @ determine the location of the registers saved by the core during
+ @ exception entry. Depending on the mode the cpu was in when the
+ @ exception happend that is either on the main or the process stack.
+ @ Bit 2 of EXC_RETURN stored in the lr register specifies which stack
+ @ was used.
+ tst lr, #EXC_RET_STACK_MASK
+ mrsne r12, psp
+ moveq r12, sp
+
+ @ we cannot rely on r0-r3 and r12 matching the value saved in the
+ @ exception frame because of tail-chaining. So these have to be
+ @ reloaded.
+ ldmia r12!, {r0-r3}
+
+ @ Linux expects to have irqs off. Do it here before taking stack space
+ cpsid i
+
+ sub sp, #PT_REGS_SIZE-S_IP
+ stmdb sp!, {r0-r11}
+
+ @ load saved r12, lr, return address and xPSR.
+ @ r0-r7 are used for signals and never touched from now on. Clobbering
+ @ r8-r12 is OK.
+ mov r9, r12
+ ldmia r9!, {r8, r10-r12}
+
+ @ calculate the original stack pointer value.
+ @ r9 currently points to the memory location just above the auto saved
+ @ xPSR.
+ @ The cpu might automatically 8-byte align the stack. Bit 9
+ @ of the saved xPSR specifies if stack aligning took place. In this case
+ @ another 32-bit value is included in the stack.
+
+ tst r12, V7M_xPSR_FRAMEPTRALIGN
+ addne r9, r9, #4
+
+ @ store saved r12 using str to have a register to hold the base for stm
+ str r8, [sp, #S_IP]
+ add r8, sp, #S_SP
+ @ store r13-r15, xPSR
+ stmia r8!, {r9-r12}
+ @ store old_r0
+ str r0, [r8]
+ .endm
+
+ /*
+ * PENDSV and SVCALL are configured to have the same exception
+ * priorities. As a kernel thread runs at SVCALL execution priority it
+ * can never be preempted and so we will never have to return to a
+ * kernel thread here.
+ */
+ .macro v7m_exception_slow_exit ret_r0
+ cpsid i
+ ldr lr, =EXC_RET_THREADMODE_PROCESSSTACK
+
+ @ read original r12, sp, lr, pc and xPSR
+ add r12, sp, #S_IP
+ ldmia r12, {r1-r5}
+
+ @ an exception frame is always 8-byte aligned. To tell the hardware if
+ @ the sp to be restored is aligned or not set bit 9 of the saved xPSR
+ @ accordingly.
+ tst r2, #4
+ subne r2, r2, #4
+ orrne r5, V7M_xPSR_FRAMEPTRALIGN
+ biceq r5, V7M_xPSR_FRAMEPTRALIGN
+
+ @ ensure bit 0 is cleared in the PC, otherwise behaviour is
+ @ unpredictable
+ bic r4, #1
+
+ @ write basic exception frame
+ stmdb r2!, {r1, r3-r5}
+ ldmia sp, {r1, r3-r5}
+ .if \ret_r0
+ stmdb r2!, {r0, r3-r5}
+ .else
+ stmdb r2!, {r1, r3-r5}
+ .endif
+
+ @ restore process sp
+ msr psp, r2
+
+ @ restore original r4-r11
+ ldmia sp!, {r0-r11}
+
+ @ restore main sp
+ add sp, sp, #PT_REGS_SIZE-S_IP
+
+ cpsie i
+ bx lr
+ .endm
+#endif /* CONFIG_CPU_V7M */
+
+ @
+ @ Store/load the USER SP and LR registers by switching to the SYS
+ @ mode. Useful in Thumb-2 mode where "stm/ldm rd, {sp, lr}^" is not
+ @ available. Should only be called from SVC mode
+ @
+ .macro store_user_sp_lr, rd, rtemp, offset = 0
+ mrs \rtemp, cpsr
+ eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
+ msr cpsr_c, \rtemp @ switch to the SYS mode
+
+ str sp, [\rd, #\offset] @ save sp_usr
+ str lr, [\rd, #\offset + 4] @ save lr_usr
+
+ eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
+ msr cpsr_c, \rtemp @ switch back to the SVC mode
+ .endm
+
+ .macro load_user_sp_lr, rd, rtemp, offset = 0
+ mrs \rtemp, cpsr
+ eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
+ msr cpsr_c, \rtemp @ switch to the SYS mode
+
+ ldr sp, [\rd, #\offset] @ load sp_usr
+ ldr lr, [\rd, #\offset + 4] @ load lr_usr
+
+ eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
+ msr cpsr_c, \rtemp @ switch back to the SVC mode
+ .endm
+
+
+ .macro svc_exit, rpsr, irq = 0
+ .if \irq != 0
+ @ IRQs already off
+#ifdef CONFIG_TRACE_IRQFLAGS
+ @ The parent context IRQs must have been enabled to get here in
+ @ the first place, so there's no point checking the PSR I bit.
+ bl trace_hardirqs_on
+#endif
+ .else
+ @ IRQs off again before pulling preserved data off the stack
+ disable_irq_notrace
+#ifdef CONFIG_TRACE_IRQFLAGS
+ tst \rpsr, #PSR_I_BIT
+ bleq trace_hardirqs_on
+ tst \rpsr, #PSR_I_BIT
+ blne trace_hardirqs_off
+#endif
+ .endif
+ ldr r1, [sp, #SVC_ADDR_LIMIT]
+ uaccess_restore
+ str r1, [tsk, #TI_ADDR_LIMIT]
+
+#ifndef CONFIG_THUMB2_KERNEL
+ @ ARM mode SVC restore
+ msr spsr_cxsf, \rpsr
+#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
+ @ We must avoid clrex due to Cortex-A15 erratum #830321
+ sub r0, sp, #4 @ uninhabited address
+ strex r1, r2, [r0] @ clear the exclusive monitor
+#endif
+ ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
+#else
+ @ Thumb mode SVC restore
+ ldr lr, [sp, #S_SP] @ top of the stack
+ ldrd r0, r1, [sp, #S_LR] @ calling lr and pc
+
+ @ We must avoid clrex due to Cortex-A15 erratum #830321
+ strex r2, r1, [sp, #S_LR] @ clear the exclusive monitor
+
+ stmdb lr!, {r0, r1, \rpsr} @ calling lr and rfe context
+ ldmia sp, {r0 - r12}
+ mov sp, lr
+ ldr lr, [sp], #4
+ rfeia sp!
+#endif
+ .endm
+
+ @
+ @ svc_exit_via_fiq - like svc_exit but switches to FIQ mode before exit
+ @
+ @ This macro acts in a similar manner to svc_exit but switches to FIQ
+ @ mode to restore the final part of the register state.
+ @
+ @ We cannot use the normal svc_exit procedure because that would
+ @ clobber spsr_svc (FIQ could be delivered during the first few
+ @ instructions of vector_swi meaning its contents have not been
+ @ saved anywhere).
+ @
+ @ Note that, unlike svc_exit, this macro also does not allow a caller
+ @ supplied rpsr. This is because the FIQ exceptions are not re-entrant
+ @ and the handlers cannot call into the scheduler (meaning the value
+ @ on the stack remains correct).
+ @
+ .macro svc_exit_via_fiq
+ ldr r1, [sp, #SVC_ADDR_LIMIT]
+ uaccess_restore
+ str r1, [tsk, #TI_ADDR_LIMIT]
+#ifndef CONFIG_THUMB2_KERNEL
+ @ ARM mode restore
+ mov r0, sp
+ ldmib r0, {r1 - r14} @ abort is deadly from here onward (it will
+ @ clobber state restored below)
+ msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
+ add r8, r0, #S_PC
+ ldr r9, [r0, #S_PSR]
+ msr spsr_cxsf, r9
+ ldr r0, [r0, #S_R0]
+ ldmia r8, {pc}^
+#else
+ @ Thumb mode restore
+ add r0, sp, #S_R2
+ ldr lr, [sp, #S_LR]
+ ldr sp, [sp, #S_SP] @ abort is deadly from here onward (it will
+ @ clobber state restored below)
+ ldmia r0, {r2 - r12}
+ mov r1, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
+ msr cpsr_c, r1
+ sub r0, #S_R2
+ add r8, r0, #S_PC
+ ldmia r0, {r0 - r1}
+ rfeia r8
+#endif
+ .endm
+
+
+ .macro restore_user_regs, fast = 0, offset = 0
+ uaccess_enable r1, isb=0
+#ifndef CONFIG_THUMB2_KERNEL
+ @ ARM mode restore
+ mov r2, sp
+ ldr r1, [r2, #\offset + S_PSR] @ get calling cpsr
+ ldr lr, [r2, #\offset + S_PC]! @ get pc
+ tst r1, #PSR_I_BIT | 0x0f
+ bne 1f
+ msr spsr_cxsf, r1 @ save in spsr_svc
+#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
+ @ We must avoid clrex due to Cortex-A15 erratum #830321
+ strex r1, r2, [r2] @ clear the exclusive monitor
+#endif
+ .if \fast
+ ldmdb r2, {r1 - lr}^ @ get calling r1 - lr
+ .else
+ ldmdb r2, {r0 - lr}^ @ get calling r0 - lr
+ .endif
+ mov r0, r0 @ ARMv5T and earlier require a nop
+ @ after ldm {}^
+ add sp, sp, #\offset + PT_REGS_SIZE
+ movs pc, lr @ return & move spsr_svc into cpsr
+1: bug "Returning to usermode but unexpected PSR bits set?", \@
+#elif defined(CONFIG_CPU_V7M)
+ @ V7M restore.
+ @ Note that we don't need to do clrex here as clearing the local
+ @ monitor is part of the exception entry and exit sequence.
+ .if \offset
+ add sp, #\offset
+ .endif
+ v7m_exception_slow_exit ret_r0 = \fast
+#else
+ @ Thumb mode restore
+ mov r2, sp
+ load_user_sp_lr r2, r3, \offset + S_SP @ calling sp, lr
+ ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
+ ldr lr, [sp, #\offset + S_PC] @ get pc
+ add sp, sp, #\offset + S_SP
+ tst r1, #PSR_I_BIT | 0x0f
+ bne 1f
+ msr spsr_cxsf, r1 @ save in spsr_svc
+
+ @ We must avoid clrex due to Cortex-A15 erratum #830321
+ strex r1, r2, [sp] @ clear the exclusive monitor
+
+ .if \fast
+ ldmdb sp, {r1 - r12} @ get calling r1 - r12
+ .else
+ ldmdb sp, {r0 - r12} @ get calling r0 - r12
+ .endif
+ add sp, sp, #PT_REGS_SIZE - S_SP
+ movs pc, lr @ return & move spsr_svc into cpsr
+1: bug "Returning to usermode but unexpected PSR bits set?", \@
+#endif /* !CONFIG_THUMB2_KERNEL */
+ .endm
+
+/*
+ * Context tracking subsystem. Used to instrument transitions
+ * between user and kernel mode.
+ */
+ .macro ct_user_exit, save = 1
+#ifdef CONFIG_CONTEXT_TRACKING
+ .if \save
+ stmdb sp!, {r0-r3, ip, lr}
+ bl context_tracking_user_exit
+ ldmia sp!, {r0-r3, ip, lr}
+ .else
+ bl context_tracking_user_exit
+ .endif
+#endif
+ .endm
+
+ .macro ct_user_enter, save = 1
+#ifdef CONFIG_CONTEXT_TRACKING
+ .if \save
+ stmdb sp!, {r0-r3, ip, lr}
+ bl context_tracking_user_enter
+ ldmia sp!, {r0-r3, ip, lr}
+ .else
+ bl context_tracking_user_enter
+ .endif
+#endif
+ .endm
+
+ .macro invoke_syscall, table, nr, tmp, ret, reload=0
+#ifdef CONFIG_CPU_SPECTRE
+ mov \tmp, \nr
+ cmp \tmp, #NR_syscalls @ check upper syscall limit
+ movcs \tmp, #0
+ csdb
+ badr lr, \ret @ return address
+ .if \reload
+ add r1, sp, #S_R0 + S_OFF @ pointer to regs
+ ldmccia r1, {r0 - r6} @ reload r0-r6
+ stmccia sp, {r4, r5} @ update stack arguments
+ .endif
+ ldrcc pc, [\table, \tmp, lsl #2] @ call sys_* routine
+#else
+ cmp \nr, #NR_syscalls @ check upper syscall limit
+ badr lr, \ret @ return address
+ .if \reload
+ add r1, sp, #S_R0 + S_OFF @ pointer to regs
+ ldmccia r1, {r0 - r6} @ reload r0-r6
+ stmccia sp, {r4, r5} @ update stack arguments
+ .endif
+ ldrcc pc, [\table, \nr, lsl #2] @ call sys_* routine
+#endif
+ .endm
+
+/*
+ * These are the registers used in the syscall handler, and allow us to
+ * have in theory up to 7 arguments to a function - r0 to r6.
+ *
+ * r7 is reserved for the system call number for thumb mode.
+ *
+ * Note that tbl == why is intentional.
+ *
+ * We must set at least "tsk" and "why" when calling ret_with_reschedule.
+ */
+scno .req r7 @ syscall number
+tbl .req r8 @ syscall table pointer
+why .req r8 @ Linux syscall (!= 0)
+tsk .req r9 @ current thread_info