arch/hexagon/kernel/vm_entry.S

   1 /*
   2  * Event entry/exit for Hexagon
   3  *
   4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #include <asm/asm-offsets.h>  /*  assembly-safer versions of C defines */
  22 #include <asm/mem-layout.h>   /*  sigh, except for page_offset  */
  23 #include <asm/hexagon_vm.h>
  24 #include <asm/thread_info.h>
  25
  26 /*
  27  * Entry into guest-mode Linux under Hexagon Virtual Machine.
  28  * Stack pointer points to event record - build pt_regs on top of it,
  29  * set up a plausible C stack frame, and dispatch to the C handler.
  30  * On return, do vmrte virtual instruction with SP where we started.
  31  *
  32  * VM Spec 0.5 uses a trap to fetch HVM record now.
  33  */
  34
  35 /*
  36  * Save full register state, while setting up thread_info struct
  37  * pointer derived from kernel stack pointer in THREADINFO_REG
  38  * register, putting prior thread_info.regs pointer in a callee-save
  39  * register (R24, which had better not ever be assigned to THREADINFO_REG),
  40  * and updating thread_info.regs to point to current stack frame,
  41  * so as to support nested events in kernel mode.
  42  *
  43  * As this is common code, we set the pt_regs system call number
  44  * to -1 for all events.  It will be replaced with the system call
  45  * number in the case where we decode a system call (trap0(#1)).
  46  */
  47
  48 #define save_pt_regs()\
  49         memd(R0 + #_PT_R3130) = R31:30; \
  50         { memw(R0 + #_PT_R2928) = R28; \
  51           R31 = memw(R0 + #_PT_ER_VMPSP); }\
  52         { memw(R0 + #(_PT_R2928 + 4)) = R31; \
  53           R31 = ugp; } \
  54         { memd(R0 + #_PT_R2726) = R27:26; \
  55           R30 = gp ; } \
  56         memd(R0 + #_PT_R2524) = R25:24; \
  57         memd(R0 + #_PT_R2322) = R23:22; \
  58         memd(R0 + #_PT_R2120) = R21:20; \
  59         memd(R0 + #_PT_R1918) = R19:18; \
  60         memd(R0 + #_PT_R1716) = R17:16; \
  61         memd(R0 + #_PT_R1514) = R15:14; \
  62         memd(R0 + #_PT_R1312) = R13:12; \
  63         { memd(R0 + #_PT_R1110) = R11:10; \
  64           R15 = lc0; } \
  65         { memd(R0 + #_PT_R0908) = R9:8; \
  66           R14 = sa0; } \
  67         { memd(R0 + #_PT_R0706) = R7:6; \
  68           R13 = lc1; } \
  69         { memd(R0 + #_PT_R0504) = R5:4; \
  70           R12 = sa1; } \
  71         { memd(R0 + #_PT_UGPGP) = R31:30; \
  72           R11 = m1; \
  73           R2.H = #HI(_THREAD_SIZE); } \
  74         { memd(R0 + #_PT_LC0SA0) = R15:14; \
  75           R10 = m0; \
  76           R2.L = #LO(_THREAD_SIZE); } \
  77         { memd(R0 + #_PT_LC1SA1) = R13:12; \
  78           R15 = p3:0; \
  79           R2 = neg(R2); } \
  80         { memd(R0 + #_PT_M1M0) = R11:10; \
  81           R14  = usr; \
  82           R2 = and(R0,R2); } \
  83         { memd(R0 + #_PT_PREDSUSR) =  R15:14; \
  84           THREADINFO_REG = R2; } \
  85         { r24 = memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS); \
  86           memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS) = R0; \
  87           R2 = #-1; } \
  88         { memw(R0 + #_PT_SYSCALL_NR) = R2; \
  89           R30 = #0; }
  90
  91 /*
  92  * Restore registers and thread_info.regs state. THREADINFO_REG
  93  * is assumed to still be sane, and R24 to have been correctly
  94  * preserved. Don't restore R29 (SP) until later.
  95  */
  96
  97 #define restore_pt_regs() \
  98         { memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS) = R24; \
  99           R15:14 = memd(R0 + #_PT_PREDSUSR); } \
 100         { R11:10 = memd(R0 + #_PT_M1M0); \
 101           p3:0 = R15; } \
 102         { R13:12 = memd(R0 + #_PT_LC1SA1); \
 103           usr = R14; } \
 104         { R15:14 = memd(R0 + #_PT_LC0SA0); \
 105           m1 = R11; } \
 106         { R3:2 = memd(R0 + #_PT_R0302); \
 107           m0 = R10; } \
 108         { R5:4 = memd(R0 + #_PT_R0504); \
 109           lc1 = R13; } \
 110         { R7:6 = memd(R0 + #_PT_R0706); \
 111           sa1 = R12; } \
 112         { R9:8 = memd(R0 + #_PT_R0908); \
 113           lc0 = R15; } \
 114         { R11:10 = memd(R0 + #_PT_R1110); \
 115           sa0 = R14; } \
 116         { R13:12 = memd(R0 + #_PT_R1312); \
 117           R15:14 = memd(R0 + #_PT_R1514); } \
 118         { R17:16 = memd(R0 + #_PT_R1716); \
 119           R19:18 = memd(R0 + #_PT_R1918); } \
 120         { R21:20 = memd(R0 + #_PT_R2120); \
 121           R23:22 = memd(R0 + #_PT_R2322); } \
 122         { R25:24 = memd(R0 + #_PT_R2524); \
 123           R27:26 = memd(R0 + #_PT_R2726); } \
 124         R31:30 = memd(R0 + #_PT_UGPGP); \
 125         { R28 = memw(R0 + #_PT_R2928); \
 126           ugp = R31; } \
 127         { R31:30 = memd(R0 + #_PT_R3130); \
 128           gp = R30; }
 129
 130         /*
 131          * Clears off enough space for the rest of pt_regs; evrec is a part
 132          * of pt_regs in HVM mode.  Save R0/R1, set handler's address in R1.
 133          * R0 is the address of pt_regs and is the parameter to save_pt_regs.
 134          */
 135
 136 /*
 137  * Since the HVM isn't automagically pushing the EVREC onto the stack anymore,
 138  * we'll subract the entire size out and then fill it in ourselves.
 139  * Need to save off R0, R1, R2, R3 immediately.
 140  */
 141
 142 #define vm_event_entry(CHandler) \
 143         { \
 144                 R29 = add(R29, #-(_PT_REGS_SIZE)); \
 145                 memd(R29 + #(_PT_R0100 + -_PT_REGS_SIZE)) = R1:0; \
 146         } \
 147         { \
 148                 memd(R29 +#_PT_R0302) = R3:2; \
 149         } \
 150         trap1(#HVM_TRAP1_VMGETREGS); \
 151         { \
 152                 memd(R29 + #_PT_ER_VMEL) = R1:0; \
 153                 R0 = R29; \
 154                 R1.L = #LO(CHandler); \
 155         } \
 156         { \
 157                 memd(R29 + #_PT_ER_VMPSP) = R3:2; \
 158                 R1.H = #HI(CHandler); \
 159                 jump event_dispatch; \
 160         }
 161
 162 .text
 163         /*
 164          * Do bulk save/restore in one place.
 165          * Adds a jump to dispatch latency, but
 166          * saves hundreds of bytes.
 167          */
 168
 169 event_dispatch:
 170         save_pt_regs()
 171         callr   r1
 172
 173         /*
 174          * If we were in kernel mode, we don't need to check scheduler
 175          * or signals if CONFIG_PREEMPT is not set.  If set, then it has
 176          * to jump to a need_resched kind of block.
 177          * BTW, CONFIG_PREEMPT is not supported yet.
 178          */
 179
 180 #ifdef CONFIG_PREEMPT
 181         R0 = #VM_INT_DISABLE
 182         trap1(#HVM_TRAP1_VMSETIE)
 183 #endif
 184
 185         /*  "Nested control path" -- if the previous mode was kernel  */
 186         R0 = memw(R29 + #_PT_ER_VMEST);
 187         P0 = tstbit(R0, #HVM_VMEST_UM_SFT);
 188         if !P0 jump restore_all;
 189         /*
 190          * Returning from system call, normally coming back from user mode
 191          */
 192 return_from_syscall:
 193         /*  Disable interrupts while checking TIF  */
 194         R0 = #VM_INT_DISABLE
 195         trap1(#HVM_TRAP1_VMSETIE)
 196
 197         /*
 198          * Coming back from the C-world, our thread info pointer
 199          * should be in the designated register (usually R19)
 200          */
 201         R1.L = #LO(_TIF_ALLWORK_MASK)
 202         {
 203                 R1.H = #HI(_TIF_ALLWORK_MASK);
 204                 R0 = memw(THREADINFO_REG + #_THREAD_INFO_FLAGS);
 205         }
 206
 207         /*
 208          * Compare against the "return to userspace" _TIF_WORK_MASK
 209          */
 210         R1 = and(R1,R0);
 211         { P0 = cmp.eq(R1,#0); if (!P0.new) jump:t work_pending;}
 212         jump restore_all;  /*  we're outta here!  */
 213
 214 work_pending:
 215         {
 216                 P0 = tstbit(R1, #TIF_NEED_RESCHED);
 217                 if (!P0.new) jump:nt work_notifysig;
 218         }
 219         call schedule
 220         jump return_from_syscall;  /*  check for more work  */
 221
 222 work_notifysig:
 223         /*  this is the part that's kind of fuzzy.  */
 224         R1 = and(R0, #(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME));
 225         P0 = cmp.eq(R1, #0);
 226         if P0 jump restore_all
 227         R1 = R0;        /* unsigned long thread_info_flags */
 228         R0 = R29;       /* regs should still be at top of stack  */
 229         call do_notify_resume
 230
 231 restore_all:
 232         /* Disable interrupts, if they weren't already, before reg restore.  */
 233         R0 = #VM_INT_DISABLE
 234         trap1(#HVM_TRAP1_VMSETIE)
 235
 236         /*  do the setregs here for VM 0.5  */
 237         /*  R29 here should already be pointing at pt_regs  */
 238         R1:0 = memd(R29 + #_PT_ER_VMEL);
 239         R3:2 = memd(R29 + #_PT_ER_VMPSP);
 240         trap1(#HVM_TRAP1_VMSETREGS);
 241
 242         R0 = R29
 243         restore_pt_regs()
 244         R1:0 = memd(R29 + #_PT_R0100);
 245         R29 = add(R29, #_PT_REGS_SIZE);
 246         trap1(#HVM_TRAP1_VMRTE)
 247         /* Notreached */
 248
 249         .globl _K_enter_genex
 250 _K_enter_genex:
 251         vm_event_entry(do_genex)
 252
 253         .globl _K_enter_interrupt
 254 _K_enter_interrupt:
 255         vm_event_entry(arch_do_IRQ)
 256
 257         .globl _K_enter_trap0
 258 _K_enter_trap0:
 259         vm_event_entry(do_trap0)
 260
 261         .globl _K_enter_machcheck
 262 _K_enter_machcheck:
 263         vm_event_entry(do_machcheck)
 264
 265
 266         .globl ret_from_fork
 267 ret_from_fork:
 268         call schedule_tail
 269         jump return_from_syscall