arch/arm/kernel/hyp-stub.S

   1 /*
   2  * Copyright (c) 2012 Linaro Limited.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #include <linux/init.h>
  20 #include <linux/irqchip/arm-gic-v3.h>
  21 #include <linux/linkage.h>
  22 #include <asm/assembler.h>
  23 #include <asm/virt.h>
  24
  25 #ifndef ZIMAGE
  26 /*
  27  * For the kernel proper, we need to find out the CPU boot mode long after
  28  * boot, so we need to store it in a writable variable.
  29  *
  30  * This is not in .bss, because we set it sufficiently early that the boot-time
  31  * zeroing of .bss would clobber it.
  32  */
  33 .data
  34 ENTRY(__boot_cpu_mode)
  35         .long   0
  36 .text
  37
  38         /*
  39          * Save the primary CPU boot mode. Requires 3 scratch registers.
  40          */
  41         .macro  store_primary_cpu_mode  reg1, reg2, reg3
  42         mrs     \reg1, cpsr
  43         and     \reg1, \reg1, #MODE_MASK
  44         adr     \reg2, .L__boot_cpu_mode_offset
  45         ldr     \reg3, [\reg2]
  46         str     \reg1, [\reg2, \reg3]
  47         .endm
  48
  49         /*
  50          * Compare the current mode with the one saved on the primary CPU.
  51          * If they don't match, record that fact. The Z bit indicates
  52          * if there's a match or not.
  53          * Requires 3 additionnal scratch registers.
  54          */
  55         .macro  compare_cpu_mode_with_primary mode, reg1, reg2, reg3
  56         adr     \reg2, .L__boot_cpu_mode_offset
  57         ldr     \reg3, [\reg2]
  58         ldr     \reg1, [\reg2, \reg3]
  59         cmp     \mode, \reg1            @ matches primary CPU boot mode?
  60         orrne   \reg1, \reg1, #BOOT_CPU_MODE_MISMATCH
  61         strne   \reg1, [\reg2, \reg3]   @ record what happened and give up
  62         .endm
  63
  64 #else   /* ZIMAGE */
  65
  66         .macro  store_primary_cpu_mode  reg1:req, reg2:req, reg3:req
  67         .endm
  68
  69 /*
  70  * The zImage loader only runs on one CPU, so we don't bother with mult-CPU
  71  * consistency checking:
  72  */
  73         .macro  compare_cpu_mode_with_primary mode, reg1, reg2, reg3
  74         cmp     \mode, \mode
  75         .endm
  76
  77 #endif /* ZIMAGE */
  78
  79 /*
  80  * Hypervisor stub installation functions.
  81  *
  82  * These must be called with the MMU and D-cache off.
  83  * They are not ABI compliant and are only intended to be called from the kernel
  84  * entry points in head.S.
  85  */
  86 @ Call this from the primary CPU
  87 ENTRY(__hyp_stub_install)
  88         store_primary_cpu_mode  r4, r5, r6
  89 ENDPROC(__hyp_stub_install)
  90
  91         @ fall through...
  92
  93 @ Secondary CPUs should call here
  94 ENTRY(__hyp_stub_install_secondary)
  95         mrs     r4, cpsr
  96         and     r4, r4, #MODE_MASK
  97
  98         /*
  99          * If the secondary has booted with a different mode, give up
 100          * immediately.
 101          */
 102         compare_cpu_mode_with_primary   r4, r5, r6, r7
 103         retne   lr
 104
 105         /*
 106          * Once we have given up on one CPU, we do not try to install the
 107          * stub hypervisor on the remaining ones: because the saved boot mode
 108          * is modified, it can't compare equal to the CPSR mode field any
 109          * more.
 110          *
 111          * Otherwise...
 112          */
 113
 114         cmp     r4, #HYP_MODE
 115         retne   lr                      @ give up if the CPU is not in HYP mode
 116
 117 /*
 118  * Configure HSCTLR to set correct exception endianness/instruction set
 119  * state etc.
 120  * Turn off all traps
 121  * Eventually, CPU-specific code might be needed -- assume not for now
 122  *
 123  * This code relies on the "eret" instruction to synchronize the
 124  * various coprocessor accesses. This is done when we switch to SVC
 125  * (see safe_svcmode_maskall).
 126  */
 127         @ Now install the hypervisor stub:
 128         adr     r7, __hyp_stub_vectors
 129         mcr     p15, 4, r7, c12, c0, 0  @ set hypervisor vector base (HVBAR)
 130
 131         @ Disable all traps, so we don't get any nasty surprise
 132         mov     r7, #0
 133         mcr     p15, 4, r7, c1, c1, 0   @ HCR
 134         mcr     p15, 4, r7, c1, c1, 2   @ HCPTR
 135         mcr     p15, 4, r7, c1, c1, 3   @ HSTR
 136
 137 THUMB(  orr     r7, #(1 << 30)  )       @ HSCTLR.TE
 138 ARM_BE8(orr     r7, r7, #(1 << 25))     @ HSCTLR.EE
 139         mcr     p15, 4, r7, c1, c0, 0   @ HSCTLR
 140
 141         mrc     p15, 4, r7, c1, c1, 1   @ HDCR
 142         and     r7, #0x1f               @ Preserve HPMN
 143         mcr     p15, 4, r7, c1, c1, 1   @ HDCR
 144
 145 #if !defined(ZIMAGE) && defined(CONFIG_ARM_ARCH_TIMER)
 146         @ make CNTP_* and CNTPCT accessible from PL1
 147         mrc     p15, 0, r7, c0, c1, 1   @ ID_PFR1
 148         lsr     r7, #16
 149         and     r7, #0xf
 150         cmp     r7, #1
 151         bne     1f
 152         mrc     p15, 4, r7, c14, c1, 0  @ CNTHCTL
 153         orr     r7, r7, #3              @ PL1PCEN | PL1PCTEN
 154         mcr     p15, 4, r7, c14, c1, 0  @ CNTHCTL
 155         mov     r7, #0
 156         mcrr    p15, 4, r7, r7, c14     @ CNTVOFF
 157
 158         @ Disable virtual timer in case it was counting
 159         mrc     p15, 0, r7, c14, c3, 1  @ CNTV_CTL
 160         bic     r7, #1                  @ Clear ENABLE
 161         mcr     p15, 0, r7, c14, c3, 1  @ CNTV_CTL
 162 1:
 163 #endif
 164
 165 #ifdef CONFIG_ARM_GIC_V3
 166         @ Check whether GICv3 system registers are available
 167         mrc     p15, 0, r7, c0, c1, 1   @ ID_PFR1
 168         ubfx    r7, r7, #28, #4
 169         cmp     r7, #1
 170         bne     2f
 171
 172         @ Enable system register accesses
 173         mrc     p15, 4, r7, c12, c9, 5  @ ICC_HSRE
 174         orr     r7, r7, #(ICC_SRE_EL2_ENABLE | ICC_SRE_EL2_SRE)
 175         mcr     p15, 4, r7, c12, c9, 5  @ ICC_HSRE
 176         isb
 177
 178         @ SRE bit could be forced to 0 by firmware.
 179         @ Check whether it sticks before accessing any other sysreg
 180         mrc     p15, 4, r7, c12, c9, 5  @ ICC_HSRE
 181         tst     r7, #ICC_SRE_EL2_SRE
 182         beq     2f
 183         mov     r7, #0
 184         mcr     p15, 4, r7, c12, c11, 0 @ ICH_HCR
 185 2:
 186 #endif
 187
 188         bx      lr                      @ The boot CPU mode is left in r4.
 189 ENDPROC(__hyp_stub_install_secondary)
 190
 191 __hyp_stub_do_trap:
 192         cmp     r0, #-1
 193         mrceq   p15, 4, r0, c12, c0, 0  @ get HVBAR
 194         mcrne   p15, 4, r0, c12, c0, 0  @ set HVBAR
 195         __ERET
 196 ENDPROC(__hyp_stub_do_trap)
 197
 198 /*
 199  * __hyp_set_vectors: Call this after boot to set the initial hypervisor
 200  * vectors as part of hypervisor installation.  On an SMP system, this should
 201  * be called on each CPU.
 202  *
 203  * r0 must be the physical address of the new vector table (which must lie in
 204  * the bottom 4GB of physical address space.
 205  *
 206  * r0 must be 32-byte aligned.
 207  *
 208  * Before calling this, you must check that the stub hypervisor is installed
 209  * everywhere, by waiting for any secondary CPUs to be brought up and then
 210  * checking that BOOT_CPU_MODE_HAVE_HYP(__boot_cpu_mode) is true.
 211  *
 212  * If not, there is a pre-existing hypervisor, some CPUs failed to boot, or
 213  * something else went wrong... in such cases, trying to install a new
 214  * hypervisor is unlikely to work as desired.
 215  *
 216  * When you call into your shiny new hypervisor, sp_hyp will contain junk,
 217  * so you will need to set that to something sensible at the new hypervisor's
 218  * initialisation entry point.
 219  */
 220 ENTRY(__hyp_get_vectors)
 221         mov     r0, #-1
 222 ENDPROC(__hyp_get_vectors)
 223         @ fall through
 224 ENTRY(__hyp_set_vectors)
 225         __HVC(0)
 226         ret     lr
 227 ENDPROC(__hyp_set_vectors)
 228
 229 #ifndef ZIMAGE
 230 .align 2
 231 .L__boot_cpu_mode_offset:
 232         .long   __boot_cpu_mode - .
 233 #endif
 234
 235 .align 5
 236 __hyp_stub_vectors:
 237 __hyp_stub_reset:       W(b)    .
 238 __hyp_stub_und:         W(b)    .
 239 __hyp_stub_svc:         W(b)    .
 240 __hyp_stub_pabort:      W(b)    .
 241 __hyp_stub_dabort:      W(b)    .
 242 __hyp_stub_trap:        W(b)    __hyp_stub_do_trap
 243 __hyp_stub_irq:         W(b)    .
 244 __hyp_stub_fiq:         W(b)    .
 245 ENDPROC(__hyp_stub_vectors)
 246