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
  78         msr     spsr_cxsf, \rpsr
  79         ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
  80         .endm
  81
  82         .macro  restore_user_regs, fast = 0, offset = 0
  83         ldr     r1, [sp, #\offset + S_PSR]      @ get calling cpsr
  84         ldr     lr, [sp, #\offset + S_PC]!      @ get pc
  85         msr     spsr_cxsf, r1                   @ save in spsr_svc
  86         .if     \fast
  87         ldmdb   sp, {r1 - lr}^                  @ get calling r1 - lr
  88         .else
  89         ldmdb   sp, {r0 - lr}^                  @ get calling r0 - lr
  90         .endif
  91         add     sp, sp, #S_FRAME_SIZE - S_PC
  92         movs    pc, lr                          @ return & move spsr_svc into cpsr
  93         .endm
  94
  95         .macro  get_thread_info, rd
  96         mov     \rd, sp, lsr #13
  97         mov     \rd, \rd, lsl #13
  98         .endm
  99 #else   /* CONFIG_THUMB2_KERNEL */
 100         .macro  svc_exit, rpsr
 101         ldr     r0, [sp, #S_SP]                 @ top of the stack
 102         ldr     r1, [sp, #S_PC]                 @ return address
 103         tst     r0, #4                          @ orig stack 8-byte aligned?
 104         stmdb   r0, {r1, \rpsr}                 @ rfe context
 105         ldmia   sp, {r0 - r12}
 106         ldr     lr, [sp, #S_LR]
 107         addeq   sp, sp, #S_FRAME_SIZE - 8       @ aligned
 108         addne   sp, sp, #S_FRAME_SIZE - 4       @ not aligned
 109         rfeia   sp!
 110         .endm
 111
 112         .macro  restore_user_regs, fast = 0, offset = 0
 113         mov     r2, sp
 114         load_user_sp_lr r2, r3, \offset + S_SP  @ calling sp, lr
 115         ldr     r1, [sp, #\offset + S_PSR]      @ get calling cpsr
 116         ldr     lr, [sp, #\offset + S_PC]       @ get pc
 117         add     sp, sp, #\offset + S_SP
 118         msr     spsr_cxsf, r1                   @ save in spsr_svc
 119         .if     \fast
 120         ldmdb   sp, {r1 - r12}                  @ get calling r1 - r12
 121         .else
 122         ldmdb   sp, {r0 - r12}                  @ get calling r0 - r12
 123         .endif
 124         add     sp, sp, #S_FRAME_SIZE - S_SP
 125         movs    pc, lr                          @ return & move spsr_svc into cpsr
 126         .endm
 127
 128         .macro  get_thread_info, rd
 129         mov     \rd, sp
 130         lsr     \rd, \rd, #13
 131         mov     \rd, \rd, lsl #13
 132         .endm
 133 #endif  /* !CONFIG_THUMB2_KERNEL */
 134
 135 /*
 136  * These are the registers used in the syscall handler, and allow us to
 137  * have in theory up to 7 arguments to a function - r0 to r6.
 138  *
 139  * r7 is reserved for the system call number for thumb mode.
 140  *
 141  * Note that tbl == why is intentional.
 142  *
 143  * We must set at least "tsk" and "why" when calling ret_with_reschedule.
 144  */
 145 scno    .req    r7              @ syscall number
 146 tbl     .req    r8              @ syscall table pointer
 147 why     .req    r8              @ Linux syscall (!= 0)
 148 tsk     .req    r9              @ current thread_info