Thumb-2: Implementation of the unified start-up and exceptions code

This patch implements the ARM/Thumb-2 unified kernel start-up and
exception handling code.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

9 files changed, 251 insertions, 120 deletions

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 0befd1cabf45..468425f937dd 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -34,7 +34,7 @@
         @
         @ routine called with r0 = irq number, r1 = struct pt_regs *
         @
-        adrne   lr, 1b
+        adrne   lr, BSYM(1b)
         bne     asm_do_IRQ
 
 #ifdef CONFIG_SMP
@@ -46,13 +46,13 @@
          */
         test_for_ipi r0, r6, r5, lr
         movne   r0, sp
-        adrne   lr, 1b
+        adrne   lr, BSYM(1b)
         bne     do_IPI
 
 #ifdef CONFIG_LOCAL_TIMERS
         test_for_ltirq r0, r6, r5, lr
         movne   r0, sp
-        adrne   lr, 1b
+        adrne   lr, BSYM(1b)
         bne     do_local_timer
 #endif
 #endif
@@ -70,7 +70,10 @@
  */
         .macro  inv_entry, reason
         sub     sp, sp, #S_FRAME_SIZE
-        stmib   sp, {r1 - lr}
+ ARM(   stmib   sp, {r1 - lr}           )
+ THUMB( stmia   sp, {r0 - r12}          )
+ THUMB( str     sp, [sp, #S_SP]         )
+ THUMB( str     lr, [sp, #S_LR]         )
         mov     r1, #\reason
         .endm
 
@@ -126,17 +129,24 @@ ENDPROC(__und_invalid)
         .macro  svc_entry, stack_hole=0
  UNWIND(.fnstart                )
  UNWIND(.save {r0 - pc}         )
-        sub     sp, sp, #(S_FRAME_SIZE + \stack_hole)
+        sub     sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
+#ifdef CONFIG_THUMB2_KERNEL
+ SPFIX( str     r0, [sp]        )       @ temporarily saved
+ SPFIX( mov     r0, sp          )
+ SPFIX( tst     r0, #4          )       @ test original stack alignment
+ SPFIX( ldr     r0, [sp]        )       @ restored
+#else
  SPFIX( tst     sp, #4          )
- SPFIX( bicne   sp, sp, #4      )
-        stmib   sp, {r1 - r12}
+#endif
+ SPFIX( subeq   sp, sp, #4      )
+        stmia   sp, {r1 - r12}
 
         ldmia   r0, {r1 - r3}
-        add     r5, sp, #S_SP           @ here for interlock avoidance
+        add     r5, sp, #S_SP - 4       @ here for interlock avoidance
         mov     r4, #-1                 @  ""  ""      ""       ""
-        add     r0, sp, #(S_FRAME_SIZE + \stack_hole)
- SPFIX( addne   r0, r0, #4      )
-        str     r1, [sp]                @ save the "real" r0 copied
+        add     r0, sp, #(S_FRAME_SIZE + \stack_hole - 4)
+ SPFIX( addeq   r0, r0, #4      )
+        str     r1, [sp, #-4]!          @ save the "real" r0 copied
                                         @ from the exception stack
 
         mov     r1, lr
@@ -196,9 +206,8 @@ __dabt_svc:
         @
         @ restore SPSR and restart the instruction
         @
-        ldr     r0, [sp, #S_PSR]
-        msr     spsr_cxsf, r0
-        ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
+        ldr     r2, [sp, #S_PSR]
+        svc_exit r2                             @ return from exception
  UNWIND(.fnend          )
 ENDPROC(__dabt_svc)
 
@@ -225,13 +234,12 @@ __irq_svc:
         tst     r0, #_TIF_NEED_RESCHED
         blne    svc_preempt
 #endif
-        ldr     r0, [sp, #S_PSR]                @ irqs are already disabled
-        msr     spsr_cxsf, r0
+        ldr     r4, [sp, #S_PSR]                @ irqs are already disabled
 #ifdef CONFIG_TRACE_IRQFLAGS
-        tst     r0, #PSR_I_BIT
+        tst     r4, #PSR_I_BIT
         bleq    trace_hardirqs_on
 #endif
-        ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
+        svc_exit r4                             @ return from exception
  UNWIND(.fnend          )
 ENDPROC(__irq_svc)
 
@@ -266,7 +274,7 @@ __und_svc:
         @  r0 - instruction
         @
         ldr     r0, [r2, #-4]
-        adr     r9, 1f
+        adr     r9, BSYM(1f)
         bl      call_fpe
 
         mov     r0, sp                          @ struct pt_regs *regs
@@ -280,9 +288,8 @@ __und_svc:
         @
         @ restore SPSR and restart the instruction
         @
-        ldr     lr, [sp, #S_PSR]                @ Get SVC cpsr
-        msr     spsr_cxsf, lr
-        ldmia   sp, {r0 - pc}^                  @ Restore SVC registers
+        ldr     r2, [sp, #S_PSR]                @ Get SVC cpsr
+        svc_exit r2                             @ return from exception
  UNWIND(.fnend          )
 ENDPROC(__und_svc)
 
@@ -323,9 +330,8 @@ __pabt_svc:
         @
         @ restore SPSR and restart the instruction
         @
-        ldr     r0, [sp, #S_PSR]
-        msr     spsr_cxsf, r0
-        ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
+        ldr     r2, [sp, #S_PSR]
+        svc_exit r2                             @ return from exception
  UNWIND(.fnend          )
 ENDPROC(__pabt_svc)
 
@@ -353,7 +359,8 @@ ENDPROC(__pabt_svc)
  UNWIND(.fnstart        )
  UNWIND(.cantunwind     )       @ don't unwind the user space
         sub     sp, sp, #S_FRAME_SIZE
-        stmib   sp, {r1 - r12}
+ ARM(   stmib   sp, {r1 - r12}  )
+ THUMB( stmia   sp, {r0 - r12}  )
 
         ldmia   r0, {r1 - r3}
         add     r0, sp, #S_PC           @ here for interlock avoidance
@@ -372,7 +379,8 @@ ENDPROC(__pabt_svc)
         @ Also, separately save sp_usr and lr_usr
         @
         stmia   r0, {r2 - r4}
-        stmdb   r0, {sp, lr}^
+ ARM(   stmdb   r0, {sp, lr}^                   )
+ THUMB( store_user_sp_lr r0, r1, S_SP - S_PC    )
 
         @
         @ Enable the alignment trap while in kernel mode
@@ -427,7 +435,7 @@ __dabt_usr:
         @
         enable_irq
         mov     r2, sp
-        adr     lr, ret_from_exception
+        adr     lr, BSYM(ret_from_exception)
         b       do_DataAbort
  UNWIND(.fnend          )
 ENDPROC(__dabt_usr)
@@ -452,7 +460,9 @@ __irq_usr:
         ldr     r0, [tsk, #TI_PREEMPT]
         str     r8, [tsk, #TI_PREEMPT]
         teq     r0, r7
-        strne   r0, [r0, -r0]
+ ARM(   strne   r0, [r0, -r0]   )
+ THUMB( movne   r0, #0          )
+ THUMB( strne   r0, [r0]        )
 #endif
 #ifdef CONFIG_TRACE_IRQFLAGS
         bl      trace_hardirqs_on
@@ -476,9 +486,10 @@ __und_usr:
         @
         @  r0 - instruction
         @
-        adr     r9, ret_from_exception
-        adr     lr, __und_usr_unknown
+        adr     r9, BSYM(ret_from_exception)
+        adr     lr, BSYM(__und_usr_unknown)
         tst     r3, #PSR_T_BIT                  @ Thumb mode?
+        itet    eq                              @ explicit IT needed for the 1f label
         subeq   r4, r2, #4                      @ ARM instr at LR - 4
         subne   r4, r2, #2                      @ Thumb instr at LR - 2
 1:      ldreqt  r0, [r4]
@@ -488,7 +499,10 @@ __und_usr:
         beq     call_fpe
         @ Thumb instruction
 #if __LINUX_ARM_ARCH__ >= 7
-2:      ldrht   r5, [r4], #2
+2:
+ ARM(   ldrht   r5, [r4], #2    )
+ THUMB( ldrht   r5, [r4]        )
+ THUMB( add     r4, r4, #2      )
         and     r0, r5, #0xf800                 @ mask bits 111x x... .... ....
         cmp     r0, #0xe800                     @ 32bit instruction if xx != 0
         blo     __und_usr_unknown
@@ -577,9 +591,11 @@ call_fpe:
         moveq   pc, lr
         get_thread_info r10                     @ get current thread
         and     r8, r0, #0x00000f00             @ mask out CP number
+ THUMB( lsr     r8, r8, #8              )
         mov     r7, #1
         add     r6, r10, #TI_USED_CP
-        strb    r7, [r6, r8, lsr #8]            @ set appropriate used_cp[]
+ ARM(   strb    r7, [r6, r8, lsr #8]    )       @ set appropriate used_cp[]
+ THUMB( strb    r7, [r6, r8]            )       @ set appropriate used_cp[]
 #ifdef CONFIG_IWMMXT
         @ Test if we need to give access to iWMMXt coprocessors
         ldr     r5, [r10, #TI_FLAGS]
@@ -587,36 +603,38 @@ call_fpe:
         movcss  r7, r5, lsr #(TIF_USING_IWMMXT + 1)
         bcs     iwmmxt_task_enable
 #endif
-        add     pc, pc, r8, lsr #6
-        mov     r0, r0
-
-        mov     pc, lr                          @ CP#0
-        b       do_fpe                          @ CP#1 (FPE)
-        b       do_fpe                          @ CP#2 (FPE)
-        mov     pc, lr                          @ CP#3
+ ARM(   add     pc, pc, r8, lsr #6      )
+ THUMB( lsl     r8, r8, #2              )
+ THUMB( add     pc, r8                  )
+        nop
+
+        W(mov)  pc, lr                          @ CP#0
+        W(b)    do_fpe                          @ CP#1 (FPE)
+        W(b)    do_fpe                          @ CP#2 (FPE)
+        W(mov)  pc, lr                          @ CP#3
 #ifdef CONFIG_CRUNCH
         b       crunch_task_enable              @ CP#4 (MaverickCrunch)
         b       crunch_task_enable              @ CP#5 (MaverickCrunch)
         b       crunch_task_enable              @ CP#6 (MaverickCrunch)
 #else
-        mov     pc, lr                          @ CP#4
-        mov     pc, lr                          @ CP#5
-        mov     pc, lr                          @ CP#6
+        W(mov)  pc, lr                          @ CP#4
+        W(mov)  pc, lr                          @ CP#5
+        W(mov)  pc, lr                          @ CP#6
 #endif
-        mov     pc, lr                          @ CP#7
-        mov     pc, lr                          @ CP#8
-        mov     pc, lr                          @ CP#9
+        W(mov)  pc, lr                          @ CP#7
+        W(mov)  pc, lr                          @ CP#8
+        W(mov)  pc, lr                          @ CP#9
 #ifdef CONFIG_VFP
-        b       do_vfp                          @ CP#10 (VFP)
-        b       do_vfp                          @ CP#11 (VFP)
+        W(b)    do_vfp                          @ CP#10 (VFP)
+        W(b)    do_vfp                          @ CP#11 (VFP)
 #else
-        mov     pc, lr                          @ CP#10 (VFP)
-        mov     pc, lr                          @ CP#11 (VFP)
+        W(mov)  pc, lr                          @ CP#10 (VFP)
+        W(mov)  pc, lr                          @ CP#11 (VFP)
 #endif
-        mov     pc, lr                          @ CP#12
-        mov     pc, lr                          @ CP#13
-        mov     pc, lr                          @ CP#14 (Debug)
-        mov     pc, lr                          @ CP#15 (Control)
+        W(mov)  pc, lr                          @ CP#12
+        W(mov)  pc, lr                          @ CP#13
+        W(mov)  pc, lr                          @ CP#14 (Debug)
+        W(mov)  pc, lr                          @ CP#15 (Control)
 
 #ifdef CONFIG_NEON
         .align  6
@@ -667,7 +685,7 @@ no_fp:	mov	pc, lr
 __und_usr_unknown:
         enable_irq
         mov     r0, sp
-        adr     lr, ret_from_exception
+        adr     lr, BSYM(ret_from_exception)
         b       do_undefinstr
 ENDPROC(__und_usr_unknown)
 
@@ -711,7 +729,10 @@ ENTRY(__switch_to)
  UNWIND(.cantunwind     )
         add     ip, r1, #TI_CPU_SAVE
         ldr     r3, [r2, #TI_TP_VALUE]
-        stmia   ip!, {r4 - sl, fp, sp, lr}      @ Store most regs on stack
+ ARM(   stmia   ip!, {r4 - sl, fp, sp, lr} )    @ Store most regs on stack
+ THUMB( stmia   ip!, {r4 - sl, fp}         )    @ Store most regs on stack
+ THUMB( str     sp, [ip], #4               )
+ THUMB( str     lr, [ip], #4               )
 #ifdef CONFIG_MMU
         ldr     r6, [r2, #TI_CPU_DOMAIN]
 #endif
@@ -736,8 +757,12 @@ ENTRY(__switch_to)
         ldr     r0, =thread_notify_head
         mov     r1, #THREAD_NOTIFY_SWITCH
         bl      atomic_notifier_call_chain
+ THUMB( mov     ip, r4                     )
         mov     r0, r5
-        ldmia   r4, {r4 - sl, fp, sp, pc}       @ Load all regs saved previously
+ ARM(   ldmia   r4, {r4 - sl, fp, sp, pc}  )    @ Load all regs saved previously
+ THUMB( ldmia   ip!, {r4 - sl, fp}         )    @ Load all regs saved previously
+ THUMB( ldr     sp, [ip], #4               )
+ THUMB( ldr     pc, [ip]                   )
  UNWIND(.fnend          )
 ENDPROC(__switch_to)
 
@@ -772,6 +797,7 @@ ENDPROC(__switch_to)
  * if your compiled code is not going to use the new instructions for other
  * purpose.
  */
+ THUMB( .arm    )
 
         .macro  usr_ret, reg
 #ifdef CONFIG_ARM_THUMB
@@ -1020,6 +1046,7 @@ __kuser_helper_version:				@ 0xffff0ffc
         .globl  __kuser_helper_end
 __kuser_helper_end:
 
+ THUMB( .thumb  )
 
 /*
  * Vector stubs.
@@ -1054,15 +1081,17 @@ vector_\name:
         @ Prepare for SVC32 mode.  IRQs remain disabled.
         @
         mrs     r0, cpsr
-        eor     r0, r0, #(\mode ^ SVC_MODE)
+        eor     r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE)
         msr     spsr_cxsf, r0
 
         @
         @ the branch table must immediately follow this code
         @
         and     lr, lr, #0x0f
+ THUMB( adr     r0, 1f                  )
+ THUMB( ldr     lr, [r0, lr, lsl #2]    )
         mov     r0, sp
-        ldr     lr, [pc, lr, lsl #2]
+ ARM(   ldr     lr, [pc, lr, lsl #2]    )
         movs    pc, lr                  @ branch to handler in SVC mode
 ENDPROC(vector_\name)
 
@@ -1206,14 +1235,16 @@ __stubs_end:
 
         .globl  __vectors_start
 __vectors_start:
-        swi     SYS_ERROR0
-        b       vector_und + stubs_offset
-        ldr     pc, .LCvswi + stubs_offset
-        b       vector_pabt + stubs_offset
-        b       vector_dabt + stubs_offset
-        b       vector_addrexcptn + stubs_offset
-        b       vector_irq + stubs_offset
-        b       vector_fiq + stubs_offset
+ ARM(   swi     SYS_ERROR0      )
+ THUMB( svc     #0              )
+ THUMB( nop                     )
+        W(b)    vector_und + stubs_offset
+        W(ldr)  pc, .LCvswi + stubs_offset
+        W(b)    vector_pabt + stubs_offset
+        W(b)    vector_dabt + stubs_offset
+        W(b)    vector_addrexcptn + stubs_offset
+        W(b)    vector_irq + stubs_offset
+        W(b)    vector_fiq + stubs_offset
 
         .globl  __vectors_end
 __vectors_end:
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 366e5097a41a..a0540c9f1f0c 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -33,14 +33,7 @@ ret_fast_syscall:
         /* perform architecture specific actions before user return */
         arch_ret_to_user r1, lr
 
-        @ fast_restore_user_regs
-        ldr     r1, [sp, #S_OFF + S_PSR]        @ get calling cpsr
-        ldr     lr, [sp, #S_OFF + S_PC]!        @ get pc
-        msr     spsr_cxsf, r1                   @ save in spsr_svc
-        ldmdb   sp, {r1 - lr}^                  @ get calling r1 - lr
-        mov     r0, r0
-        add     sp, sp, #S_FRAME_SIZE - S_PC
-        movs    pc, lr                          @ return & move spsr_svc into cpsr
+        restore_user_regs fast = 1, offset = S_OFF
  UNWIND(.fnend          )
 
 /*
@@ -73,14 +66,7 @@ no_work_pending:
         /* perform architecture specific actions before user return */
         arch_ret_to_user r1, lr
 
-        @ slow_restore_user_regs
-        ldr     r1, [sp, #S_PSR]                @ get calling cpsr
-        ldr     lr, [sp, #S_PC]!                @ get pc
-        msr     spsr_cxsf, r1                   @ save in spsr_svc
-        ldmdb   sp, {r0 - lr}^                  @ get calling r0 - lr
-        mov     r0, r0
-        add     sp, sp, #S_FRAME_SIZE - S_PC
-        movs    pc, lr                          @ return & move spsr_svc into cpsr
+        restore_user_regs fast = 0, offset = 0
 ENDPROC(ret_to_user)
 
 /*
@@ -182,8 +168,10 @@ ftrace_stub:
 ENTRY(vector_swi)
         sub     sp, sp, #S_FRAME_SIZE
         stmia   sp, {r0 - r12}                  @ Calling r0 - r12
-        add     r8, sp, #S_PC
-        stmdb   r8, {sp, lr}^                   @ Calling sp, lr
+ ARM(   add     r8, sp, #S_PC           )
+ ARM(   stmdb   r8, {sp, lr}^           )       @ Calling sp, lr
+ THUMB( mov     r8, sp                  )
+ THUMB( store_user_sp_lr r8, r10, S_SP  )       @ calling sp, lr
         mrs     r8, spsr                        @ called from non-FIQ mode, so ok.
         str     lr, [sp, #S_PC]                 @ Save calling PC
         str     r8, [sp, #S_PSR]                @ Save CPSR
@@ -272,7 +260,7 @@ ENTRY(vector_swi)
         bne     __sys_trace
 
         cmp     scno, #NR_syscalls              @ check upper syscall limit
-        adr     lr, ret_fast_syscall            @ return address
+        adr     lr, BSYM(ret_fast_syscall)      @ return address
         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 
         add     r1, sp, #S_OFF
@@ -293,7 +281,7 @@ __sys_trace:
         mov     r0, #0                          @ trace entry [IP = 0]
         bl      syscall_trace
 
-        adr     lr, __sys_trace_return          @ return address
+        adr     lr, BSYM(__sys_trace_return)    @ return address
         mov     scno, r0                        @ syscall number (possibly new)
         add     r1, sp, #S_R0 + S_OFF           @ pointer to regs
         cmp     scno, #NR_syscalls              @ check upper syscall limit
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 87ab4e157997..a4eaf4f920c5 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -36,11 +36,6 @@
 #endif
         .endm
 
-        .macro  get_thread_info, rd
-        mov     \rd, sp, lsr #13
-        mov     \rd, \rd, lsl #13
-        .endm
-
         .macro  alignment_trap, rtemp
 #ifdef CONFIG_ALIGNMENT_TRAP
         ldr     \rtemp, .LCcralign
@@ -49,6 +44,93 @@
 #endif
         .endm
 
+        @
+        @ 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
+
+#ifndef CONFIG_THUMB2_KERNEL
+        .macro  svc_exit, rpsr
+        msr     spsr_cxsf, \rpsr
+        ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
+        .endm
+
+        .macro  restore_user_regs, fast = 0, offset = 0
+        ldr     r1, [sp, #\offset + S_PSR]      @ get calling cpsr
+        ldr     lr, [sp, #\offset + S_PC]!      @ get pc
+        msr     spsr_cxsf, r1                   @ save in spsr_svc
+        .if     \fast
+        ldmdb   sp, {r1 - lr}^                  @ get calling r1 - lr
+        .else
+        ldmdb   sp, {r0 - lr}^                  @ get calling r0 - lr
+        .endif
+        add     sp, sp, #S_FRAME_SIZE - S_PC
+        movs    pc, lr                          @ return & move spsr_svc into cpsr
+        .endm
+
+        .macro  get_thread_info, rd
+        mov     \rd, sp, lsr #13
+        mov     \rd, \rd, lsl #13
+        .endm
+#else   /* CONFIG_THUMB2_KERNEL */
+        .macro  svc_exit, rpsr
+        ldr     r0, [sp, #S_SP]                 @ top of the stack
+        ldr     r1, [sp, #S_PC]                 @ return address
+        tst     r0, #4                          @ orig stack 8-byte aligned?
+        stmdb   r0, {r1, \rpsr}                 @ rfe context
+        ldmia   sp, {r0 - r12}
+        ldr     lr, [sp, #S_LR]
+        addeq   sp, sp, #S_FRAME_SIZE - 8       @ aligned
+        addne   sp, sp, #S_FRAME_SIZE - 4       @ not aligned
+        rfeia   sp!
+        .endm
+
+        .macro  restore_user_regs, fast = 0, offset = 0
+        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
+        msr     spsr_cxsf, r1                   @ save in spsr_svc
+        .if     \fast
+        ldmdb   sp, {r1 - r12}                  @ get calling r1 - r12
+        .else
+        ldmdb   sp, {r0 - r12}                  @ get calling r0 - r12
+        .endif
+        add     sp, sp, #S_FRAME_SIZE - S_SP
+        movs    pc, lr                          @ return & move spsr_svc into cpsr
+        .endm
+
+        .macro  get_thread_info, rd
+        mov     \rd, sp
+        lsr     \rd, \rd, #13
+        mov     \rd, \rd, lsl #13
+        .endm
+#endif  /* !CONFIG_THUMB2_KERNEL */
 
 /*
  * These are the registers used in the syscall handler, and allow us to
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index dbfaef07a1f4..93ad576b2d74 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -52,7 +52,9 @@ __mmap_switched:
         strcc   fp, [r6],#4
         bcc     1b
 
-        ldmia   r3, {r4, r5, r6, r7, sp}
+ ARM(   ldmia   r3, {r4, r5, r6, r7, sp})
+ THUMB( ldmia   r3, {r4, r5, r6, r7}    )
+ THUMB( ldr     sp, [r3, #16]           )
         str     r9, [r4]                        @ Save processor ID
         str     r1, [r5]                        @ Save machine type
         str     r2, [r6]                        @ Save atags pointer
@@ -156,7 +158,8 @@ ENDPROC(__error)
  */
 __lookup_processor_type:
         adr     r3, 3f
-        ldmda   r3, {r5 - r7}
+        ldmia   r3, {r5 - r7}
+        add     r3, r3, #8
         sub     r3, r3, r7                      @ get offset between virt&phys
         add     r5, r5, r3                      @ convert virt addresses to
         add     r6, r6, r3                      @ physical address space
@@ -187,9 +190,9 @@ ENDPROC(lookup_processor_type)
  * more information about the __proc_info and __arch_info structures.
  */
         .align  2
-        .long   __proc_info_begin
+3:      .long   __proc_info_begin
         .long   __proc_info_end
-3:      .long   .
+4:      .long   .
         .long   __arch_info_begin
         .long   __arch_info_end
 
@@ -205,7 +208,7 @@ ENDPROC(lookup_processor_type)
  *  r5 = mach_info pointer in physical address space
  */
 __lookup_machine_type:
-        adr     r3, 3b
+        adr     r3, 4b
         ldmia   r3, {r4, r5, r6}
         sub     r3, r3, r4                      @ get offset between virt&phys
         add     r5, r5, r3                      @ convert virt addresses to
diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S
index cc87e1765ed2..b16393d2b71e 100644
--- a/arch/arm/kernel/head-nommu.S
+++ b/arch/arm/kernel/head-nommu.S
@@ -34,7 +34,7 @@
  */
         .section ".text.head", "ax"
 ENTRY(stext)
-        msr     cpsr_c, #PSR_F_BIT | PSR_I_BIT | SVC_MODE @ ensure svc mode
+        setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode
                                                 @ and irqs disabled
 #ifndef CONFIG_CPU_CP15
         ldr     r9, =CONFIG_PROCESSOR_ID
@@ -50,8 +50,10 @@ ENTRY(stext)
 
         ldr     r13, __switch_data              @ address to jump to after
                                                 @ the initialization is done
-        adr     lr, __after_proc_init           @ return (PIC) address
-        add     pc, r10, #PROCINFO_INITFUNC
+        adr     lr, BSYM(__after_proc_init)     @ return (PIC) address
+ ARM(   add     pc, r10, #PROCINFO_INITFUNC     )
+ THUMB( add     r12, r10, #PROCINFO_INITFUNC    )
+ THUMB( mov     pc, r12                         )
 ENDPROC(stext)
 
 /*
@@ -82,7 +84,8 @@ __after_proc_init:
         mcr     p15, 0, r0, c1, c0, 0           @ write control reg
 #endif /* CONFIG_CPU_CP15 */
 
-        mov     pc, r13                         @ clear the BSS and jump
+        mov     r3, r13
+        mov     pc, r3                          @ clear the BSS and jump
                                                 @ to start_kernel
 ENDPROC(__after_proc_init)
         .ltorg
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 21e17dc94cb5..38ccbe1d3b2c 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -76,7 +76,7 @@
  */
         .section ".text.head", "ax"
 ENTRY(stext)
-        msr     cpsr_c, #PSR_F_BIT | PSR_I_BIT | SVC_MODE @ ensure svc mode
+        setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode
                                                 @ and irqs disabled
         mrc     p15, 0, r9, c0, c0              @ get processor id
         bl      __lookup_processor_type         @ r5=procinfo r9=cpuid
@@ -97,8 +97,10 @@ ENTRY(stext)
          */
         ldr     r13, __switch_data              @ address to jump to after
                                                 @ mmu has been enabled
-        adr     lr, __enable_mmu                @ return (PIC) address
-        add     pc, r10, #PROCINFO_INITFUNC
+        adr     lr, BSYM(__enable_mmu)          @ return (PIC) address
+ ARM(   add     pc, r10, #PROCINFO_INITFUNC     )
+ THUMB( add     r12, r10, #PROCINFO_INITFUNC    )
+ THUMB( mov     pc, r12                         )
 ENDPROC(stext)
 
 #if defined(CONFIG_SMP)
@@ -110,7 +112,7 @@ ENTRY(secondary_startup)
          * the processor type - there is no need to check the machine type
          * as it has already been validated by the primary processor.
          */
-        msr     cpsr_c, #PSR_F_BIT | PSR_I_BIT | SVC_MODE
+        setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9
         mrc     p15, 0, r9, c0, c0              @ get processor id
         bl      __lookup_processor_type
         movs    r10, r5                         @ invalid processor?
@@ -121,12 +123,15 @@ ENTRY(secondary_startup)
          * Use the page tables supplied from  __cpu_up.
          */
         adr     r4, __secondary_data
-        ldmia   r4, {r5, r7, r13}               @ address to jump to after
+        ldmia   r4, {r5, r7, r12}               @ address to jump to after
         sub     r4, r4, r5                      @ mmu has been enabled
         ldr     r4, [r7, r4]                    @ get secondary_data.pgdir
-        adr     lr, __enable_mmu                @ return address
-        add     pc, r10, #PROCINFO_INITFUNC     @ initialise processor
-                                                @ (return control reg)
+        adr     lr, BSYM(__enable_mmu)          @ return address
+        mov     r13, r12                        @ __secondary_switched address
+ ARM(   add     pc, r10, #PROCINFO_INITFUNC     ) @ initialise processor
+                                                  @ (return control reg)
+ THUMB( add     r12, r10, #PROCINFO_INITFUNC    )
+ THUMB( mov     pc, r12                         )
 ENDPROC(secondary_startup)
 
         /*
@@ -193,8 +198,8 @@ __turn_mmu_on:
         mcr     p15, 0, r0, c1, c0, 0           @ write control reg
         mrc     p15, 0, r3, c0, c0, 0           @ read id reg
         mov     r3, r3
-        mov     r3, r3
-        mov     pc, r13
+        mov     r3, r13
+        mov     pc, r3
 ENDPROC(__turn_mmu_on)
 
 
@@ -235,7 +240,8 @@ __create_page_tables:
          * will be removed by paging_init().  We use our current program
          * counter to determine corresponding section base address.
          */
-        mov     r6, pc, lsr #20                 @ start of kernel section
+        mov     r6, pc
+        mov     r6, r6, lsr #20                 @ start of kernel section
         orr     r3, r7, r6, lsl #20             @ flags + kernel base
         str     r3, [r4, r6, lsl #2]            @ identity mapping
 
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 39196dff478c..790fbee92ec5 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -388,7 +388,7 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
         regs.ARM_r2 = (unsigned long)fn;
         regs.ARM_r3 = (unsigned long)kernel_thread_exit;
         regs.ARM_pc = (unsigned long)kernel_thread_helper;
-        regs.ARM_cpsr = SVC_MODE | PSR_ENDSTATE;
+        regs.ARM_cpsr = SVC_MODE | PSR_ENDSTATE | PSR_ISETSTATE;
 
         return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 }
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index bc5e4128f9f3..d4d4f77c91b2 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -25,6 +25,7 @@
 #include <linux/smp.h>
 #include <linux/fs.h>
 
+#include <asm/unified.h>
 #include <asm/cpu.h>
 #include <asm/cputype.h>
 #include <asm/elf.h>
@@ -327,25 +328,38 @@ void cpu_init(void)
         }
 
         /*
+         * Define the placement constraint for the inline asm directive below.
+         * In Thumb-2, msr with an immediate value is not allowed.
+         */
+#ifdef CONFIG_THUMB2_KERNEL
+#define PLC     "r"
+#else
+#define PLC     "I"
+#endif
+
+        /*
          * setup stacks for re-entrant exception handlers
          */
         __asm__ (
         "msr    cpsr_c, %1\n\t"
-        "add    sp, %0, %2\n\t"
+        "add    r14, %0, %2\n\t"
+        "mov    sp, r14\n\t"
         "msr    cpsr_c, %3\n\t"
-        "add    sp, %0, %4\n\t"
+        "add    r14, %0, %4\n\t"
+        "mov    sp, r14\n\t"
         "msr    cpsr_c, %5\n\t"
-        "add    sp, %0, %6\n\t"
+        "add    r14, %0, %6\n\t"
+        "mov    sp, r14\n\t"
         "msr    cpsr_c, %7"
             :
             : "r" (stk),
-              "I" (PSR_F_BIT | PSR_I_BIT | IRQ_MODE),
+              PLC (PSR_F_BIT | PSR_I_BIT | IRQ_MODE),
               "I" (offsetof(struct stack, irq[0])),
-              "I" (PSR_F_BIT | PSR_I_BIT | ABT_MODE),
+              PLC (PSR_F_BIT | PSR_I_BIT | ABT_MODE),
               "I" (offsetof(struct stack, abt[0])),
-              "I" (PSR_F_BIT | PSR_I_BIT | UND_MODE),
+              PLC (PSR_F_BIT | PSR_I_BIT | UND_MODE),
               "I" (offsetof(struct stack, und[0])),
-              "I" (PSR_F_BIT | PSR_I_BIT | SVC_MODE)
+              PLC (PSR_F_BIT | PSR_I_BIT | SVC_MODE)
             : "r14");
 }
 
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index dd56e11f339a..39baf1128bfa 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -62,7 +62,11 @@ struct unwind_ctrl_block {
 };
 
 enum regs {
+#ifdef CONFIG_THUMB2_KERNEL
+        FP = 7,
+#else
         FP = 11,
+#endif
         SP = 13,
         LR = 14,
         PC = 15