arch/arm/kernel/entry-header.S

   1 #include <linux/init.h>
   2 #include <linux/linkage.h>
   3
   4 #include <asm/assembler.h>
   5 #include <asm/asm-offsets.h>
   6 #include <asm/errno.h>
   7 #include <asm/thread_info.h>
   8
   9 @ Bad Abort numbers
  10 @ -----------------
  11 @
  12 #define BAD_PREFETCH    0
  13 #define BAD_DATA        1
  14 #define BAD_ADDREXCPTN  2
  15 #define BAD_IRQ         3
  16 #define BAD_UNDEFINSTR  4
  17
  18 @
  19 @ Most of the stack format comes from struct pt_regs, but with
  20 @ the addition of 8 bytes for storing syscall args 5 and 6.
  21 @ This _must_ remain a multiple of 8 for EABI.
  22 @
  23 #define S_OFF           8
  24
  25 /*
  26  * The SWI code relies on the fact that R0 is at the bottom of the stack
  27  * (due to slow/fast restore user regs).
  28  */
  29 #if S_R0 != 0
  30 #error "Please fix"
  31 #endif
  32
  33         .macro  zero_fp
  34 #ifdef CONFIG_FRAME_POINTER
  35         mov     fp, #0
  36 #endif
  37         .endm
  38
  39         .macro  alignment_trap, rtemp
  40 #ifdef CONFIG_ALIGNMENT_TRAP
  41         ldr     \rtemp, .LCcralign
  42         ldr     \rtemp, [\rtemp]
  43         mcr     p15, 0, \rtemp, c1, c0
  44 #endif
  45         .endm
  46
  47         @
  48         @ Store/load the USER SP and LR registers by switching to the SYS
  49         @ mode. Useful in Thumb-2 mode where "stm/ldm rd, {sp, lr}^" is not
  50         @ available. Should only be called from SVC mode
  51         @
  52         .macro  store_user_sp_lr, rd, rtemp, offset = 0
  53         mrs     \rtemp, cpsr
  54         eor     \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
  55         msr     cpsr_c, \rtemp                  @ switch to the SYS mode
  56
  57         str     sp, [\rd, #\offset]             @ save sp_usr
  58         str     lr, [\rd, #\offset + 4]         @ save lr_usr
  59
  60         eor     \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
  61         msr     cpsr_c, \rtemp                  @ switch back to the SVC mode
  62         .endm
  63
  64         .macro  load_user_sp_lr, rd, rtemp, offset = 0
  65         mrs     \rtemp, cpsr
  66         eor     \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
  67         msr     cpsr_c, \rtemp                  @ switch to the SYS mode
  68
  69         ldr     sp, [\rd, #\offset]             @ load sp_usr
  70         ldr     lr, [\rd, #\offset + 4]         @ load lr_usr
  71
  72         eor     \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
  73         msr     cpsr_c, \rtemp                  @ switch back to the SVC mode
  74         .endm
  75
  76 #ifndef CONFIG_THUMB2_KERNEL
  77         .macro  svc_exit, rpsr, irq = 0
  78         .if     \irq != 0
  79         @ IRQs already off
  80 #ifdef CONFIG_TRACE_IRQFLAGS
  81         @ The parent context IRQs must have been enabled to get here in
  82         @ the first place, so there's no point checking the PSR I bit.
  83         bl      trace_hardirqs_on
  84 #endif
  85         .else
  86         @ IRQs off again before pulling preserved data off the stack
  87         disable_irq_notrace
  88 #ifdef CONFIG_TRACE_IRQFLAGS
  89         tst     \rpsr, #PSR_I_BIT
  90         bleq    trace_hardirqs_on
  91         tst     \rpsr, #PSR_I_BIT
  92         blne    trace_hardirqs_off
  93 #endif
  94         .endif
  95         msr     spsr_cxsf, \rpsr
  96 #if defined(CONFIG_CPU_V6)
  97         ldr     r0, [sp]
  98         strex   r1, r2, [sp]                    @ clear the exclusive monitor
  99         ldmib   sp, {r1 - pc}^                  @ load r1 - pc, cpsr
 100 #elif defined(CONFIG_CPU_32v6K)
 101         clrex                                   @ clear the exclusive monitor
 102         ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
 103 #else
 104         ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
 105 #endif
 106         .endm
 107
 108         .macro  restore_user_regs, fast = 0, offset = 0
 109         ldr     r1, [sp, #\offset + S_PSR]      @ get calling cpsr
 110         ldr     lr, [sp, #\offset + S_PC]!      @ get pc
 111         msr     spsr_cxsf, r1                   @ save in spsr_svc
 112 #if defined(CONFIG_CPU_V6)
 113         strex   r1, r2, [sp]                    @ clear the exclusive monitor
 114 #elif defined(CONFIG_CPU_32v6K)
 115         clrex                                   @ clear the exclusive monitor
 116 #endif
 117         .if     \fast
 118         ldmdb   sp, {r1 - lr}^                  @ get calling r1 - lr
 119         .else
 120         ldmdb   sp, {r0 - lr}^                  @ get calling r0 - lr
 121         .endif
 122         mov     r0, r0                          @ ARMv5T and earlier require a nop
 123                                                 @ after ldm {}^
 124         add     sp, sp, #S_FRAME_SIZE - S_PC
 125         movs    pc, lr                          @ return & move spsr_svc into cpsr
 126         .endm
 127
 128         .macro  get_thread_info, rd
 129         mov     \rd, sp, lsr #13
 130         mov     \rd, \rd, lsl #13
 131         .endm
 132
 133         @
 134         @ 32-bit wide "mov pc, reg"
 135         @
 136         .macro  movw_pc, reg
 137         mov     pc, \reg
 138         .endm
 139 #else   /* CONFIG_THUMB2_KERNEL */
 140         .macro  svc_exit, rpsr, irq = 0
 141         .if     \irq != 0
 142         @ IRQs already off
 143 #ifdef CONFIG_TRACE_IRQFLAGS
 144         @ The parent context IRQs must have been enabled to get here in
 145         @ the first place, so there's no point checking the PSR I bit.
 146         bl      trace_hardirqs_on
 147 #endif
 148         .else
 149         @ IRQs off again before pulling preserved data off the stack
 150         disable_irq_notrace
 151 #ifdef CONFIG_TRACE_IRQFLAGS
 152         tst     \rpsr, #PSR_I_BIT
 153         bleq    trace_hardirqs_on
 154         tst     \rpsr, #PSR_I_BIT
 155         blne    trace_hardirqs_off
 156 #endif
 157         .endif
 158         ldr     lr, [sp, #S_SP]                 @ top of the stack
 159         ldrd    r0, r1, [sp, #S_LR]             @ calling lr and pc
 160         clrex                                   @ clear the exclusive monitor
 161         stmdb   lr!, {r0, r1, \rpsr}            @ calling lr and rfe context
 162         ldmia   sp, {r0 - r12}
 163         mov     sp, lr
 164         ldr     lr, [sp], #4
 165         rfeia   sp!
 166         .endm
 167
 168         .macro  restore_user_regs, fast = 0, offset = 0
 169         clrex                                   @ clear the exclusive monitor
 170         mov     r2, sp
 171         load_user_sp_lr r2, r3, \offset + S_SP  @ calling sp, lr
 172         ldr     r1, [sp, #\offset + S_PSR]      @ get calling cpsr
 173         ldr     lr, [sp, #\offset + S_PC]       @ get pc
 174         add     sp, sp, #\offset + S_SP
 175         msr     spsr_cxsf, r1                   @ save in spsr_svc
 176         .if     \fast
 177         ldmdb   sp, {r1 - r12}                  @ get calling r1 - r12
 178         .else
 179         ldmdb   sp, {r0 - r12}                  @ get calling r0 - r12
 180         .endif
 181         add     sp, sp, #S_FRAME_SIZE - S_SP
 182         movs    pc, lr                          @ return & move spsr_svc into cpsr
 183         .endm
 184
 185         .macro  get_thread_info, rd
 186         mov     \rd, sp
 187         lsr     \rd, \rd, #13
 188         mov     \rd, \rd, lsl #13
 189         .endm
 190
 191         @
 192         @ 32-bit wide "mov pc, reg"
 193         @
 194         .macro  movw_pc, reg
 195         mov     pc, \reg
 196         nop
 197         .endm
 198 #endif  /* !CONFIG_THUMB2_KERNEL */
 199
 200 /*
 201  * Context tracking subsystem.  Used to instrument transitions
 202  * between user and kernel mode.
 203  */
 204         .macro ct_user_exit, save = 1
 205 #ifdef CONFIG_CONTEXT_TRACKING
 206         .if     \save
 207         stmdb   sp!, {r0-r3, ip, lr}
 208         bl      user_exit
 209         ldmia   sp!, {r0-r3, ip, lr}
 210         .else
 211         bl      user_exit
 212         .endif
 213 #endif
 214         .endm
 215
 216         .macro ct_user_enter, save = 1
 217 #ifdef CONFIG_CONTEXT_TRACKING
 218         .if     \save
 219         stmdb   sp!, {r0-r3, ip, lr}
 220         bl      user_enter
 221         ldmia   sp!, {r0-r3, ip, lr}
 222         .else
 223         bl      user_enter
 224         .endif
 225 #endif
 226         .endm
 227
 228 /*
 229  * These are the registers used in the syscall handler, and allow us to
 230  * have in theory up to 7 arguments to a function - r0 to r6.
 231  *
 232  * r7 is reserved for the system call number for thumb mode.
 233  *
 234  * Note that tbl == why is intentional.
 235  *
 236  * We must set at least "tsk" and "why" when calling ret_with_reschedule.
 237  */
 238 scno    .req    r7              @ syscall number
 239 tbl     .req    r8              @ syscall table pointer
 240 why     .req    r8              @ Linux syscall (!= 0)
 241 tsk     .req    r9              @ current thread_info