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Diffstat (limited to 'arch/arm/kernel/hyp-stub.S')
| -rw-r--r-- | arch/arm/kernel/hyp-stub.S | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/arch/arm/kernel/hyp-stub.S b/arch/arm/kernel/hyp-stub.S new file mode 100644 index 000000000..26d8e03b1 --- /dev/null +++ b/arch/arm/kernel/hyp-stub.S @@ -0,0 +1,248 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (c) 2012 Linaro Limited. + */ + +#include <linux/init.h> +#include <linux/irqchip/arm-gic-v3.h> +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/virt.h> + +#ifndef ZIMAGE +/* + * For the kernel proper, we need to find out the CPU boot mode long after + * boot, so we need to store it in a writable variable. + * + * This is not in .bss, because we set it sufficiently early that the boot-time + * zeroing of .bss would clobber it. + */ +.data + .align 2 +ENTRY(__boot_cpu_mode) + .long 0 +.text + + /* + * Save the primary CPU boot mode. Requires 3 scratch registers. + */ + .macro store_primary_cpu_mode reg1, reg2, reg3 + mrs \reg1, cpsr + and \reg1, \reg1, #MODE_MASK + adr \reg2, .L__boot_cpu_mode_offset + ldr \reg3, [\reg2] + str \reg1, [\reg2, \reg3] + .endm + + /* + * Compare the current mode with the one saved on the primary CPU. + * If they don't match, record that fact. The Z bit indicates + * if there's a match or not. + * Requires 3 additionnal scratch registers. + */ + .macro compare_cpu_mode_with_primary mode, reg1, reg2, reg3 + adr \reg2, .L__boot_cpu_mode_offset + ldr \reg3, [\reg2] + ldr \reg1, [\reg2, \reg3] + cmp \mode, \reg1 @ matches primary CPU boot mode? + orrne \reg1, \reg1, #BOOT_CPU_MODE_MISMATCH + strne \reg1, [\reg2, \reg3] @ record what happened and give up + .endm + +#else /* ZIMAGE */ + + .macro store_primary_cpu_mode reg1:req, reg2:req, reg3:req + .endm + +/* + * The zImage loader only runs on one CPU, so we don't bother with mult-CPU + * consistency checking: + */ + .macro compare_cpu_mode_with_primary mode, reg1, reg2, reg3 + cmp \mode, \mode + .endm + +#endif /* ZIMAGE */ + +/* + * Hypervisor stub installation functions. + * + * These must be called with the MMU and D-cache off. + * They are not ABI compliant and are only intended to be called from the kernel + * entry points in head.S. + */ +@ Call this from the primary CPU +ENTRY(__hyp_stub_install) + store_primary_cpu_mode r4, r5, r6 +ENDPROC(__hyp_stub_install) + + @ fall through... + +@ Secondary CPUs should call here +ENTRY(__hyp_stub_install_secondary) + mrs r4, cpsr + and r4, r4, #MODE_MASK + + /* + * If the secondary has booted with a different mode, give up + * immediately. + */ + compare_cpu_mode_with_primary r4, r5, r6, r7 + retne lr + + /* + * Once we have given up on one CPU, we do not try to install the + * stub hypervisor on the remaining ones: because the saved boot mode + * is modified, it can't compare equal to the CPSR mode field any + * more. + * + * Otherwise... + */ + + cmp r4, #HYP_MODE + retne lr @ give up if the CPU is not in HYP mode + +/* + * Configure HSCTLR to set correct exception endianness/instruction set + * state etc. + * Turn off all traps + * Eventually, CPU-specific code might be needed -- assume not for now + * + * This code relies on the "eret" instruction to synchronize the + * various coprocessor accesses. This is done when we switch to SVC + * (see safe_svcmode_maskall). + */ + @ Now install the hypervisor stub: + W(adr) r7, __hyp_stub_vectors + mcr p15, 4, r7, c12, c0, 0 @ set hypervisor vector base (HVBAR) + + @ Disable all traps, so we don't get any nasty surprise + mov r7, #0 + mcr p15, 4, r7, c1, c1, 0 @ HCR + mcr p15, 4, r7, c1, c1, 2 @ HCPTR + mcr p15, 4, r7, c1, c1, 3 @ HSTR + +THUMB( orr r7, #(1 << 30) ) @ HSCTLR.TE +ARM_BE8(orr r7, r7, #(1 << 25)) @ HSCTLR.EE + mcr p15, 4, r7, c1, c0, 0 @ HSCTLR + + mrc p15, 4, r7, c1, c1, 1 @ HDCR + and r7, #0x1f @ Preserve HPMN + mcr p15, 4, r7, c1, c1, 1 @ HDCR + + @ Make sure NS-SVC is initialised appropriately + mrc p15, 0, r7, c1, c0, 0 @ SCTLR + orr r7, #(1 << 5) @ CP15 barriers enabled + bic r7, #(3 << 7) @ Clear SED/ITD for v8 (RES0 for v7) + bic r7, #(3 << 19) @ WXN and UWXN disabled + mcr p15, 0, r7, c1, c0, 0 @ SCTLR + + mrc p15, 0, r7, c0, c0, 0 @ MIDR + mcr p15, 4, r7, c0, c0, 0 @ VPIDR + + mrc p15, 0, r7, c0, c0, 5 @ MPIDR + mcr p15, 4, r7, c0, c0, 5 @ VMPIDR + +#if !defined(ZIMAGE) && defined(CONFIG_ARM_ARCH_TIMER) + @ make CNTP_* and CNTPCT accessible from PL1 + mrc p15, 0, r7, c0, c1, 1 @ ID_PFR1 + ubfx r7, r7, #16, #4 + teq r7, #0 + beq 1f + mrc p15, 4, r7, c14, c1, 0 @ CNTHCTL + orr r7, r7, #3 @ PL1PCEN | PL1PCTEN + mcr p15, 4, r7, c14, c1, 0 @ CNTHCTL + mov r7, #0 + mcrr p15, 4, r7, r7, c14 @ CNTVOFF + + @ Disable virtual timer in case it was counting + mrc p15, 0, r7, c14, c3, 1 @ CNTV_CTL + bic r7, #1 @ Clear ENABLE + mcr p15, 0, r7, c14, c3, 1 @ CNTV_CTL +1: +#endif + +#ifdef CONFIG_ARM_GIC_V3 + @ Check whether GICv3 system registers are available + mrc p15, 0, r7, c0, c1, 1 @ ID_PFR1 + ubfx r7, r7, #28, #4 + teq r7, #0 + beq 2f + + @ Enable system register accesses + mrc p15, 4, r7, c12, c9, 5 @ ICC_HSRE + orr r7, r7, #(ICC_SRE_EL2_ENABLE | ICC_SRE_EL2_SRE) + mcr p15, 4, r7, c12, c9, 5 @ ICC_HSRE + isb + + @ SRE bit could be forced to 0 by firmware. + @ Check whether it sticks before accessing any other sysreg + mrc p15, 4, r7, c12, c9, 5 @ ICC_HSRE + tst r7, #ICC_SRE_EL2_SRE + beq 2f + mov r7, #0 + mcr p15, 4, r7, c12, c11, 0 @ ICH_HCR +2: +#endif + + bx lr @ The boot CPU mode is left in r4. +ENDPROC(__hyp_stub_install_secondary) + +__hyp_stub_do_trap: +#ifdef ZIMAGE + teq r0, #HVC_SET_VECTORS + bne 1f + /* Only the ZIMAGE stubs can change the HYP vectors */ + mcr p15, 4, r1, c12, c0, 0 @ set HVBAR + b __hyp_stub_exit +#endif + +1: teq r0, #HVC_SOFT_RESTART + bne 2f + bx r1 + +2: ldr r0, =HVC_STUB_ERR + __ERET + +__hyp_stub_exit: + mov r0, #0 + __ERET +ENDPROC(__hyp_stub_do_trap) + +/* + * __hyp_set_vectors is only used when ZIMAGE must bounce between HYP + * and SVC. For the kernel itself, the vectors are set once and for + * all by the stubs. + */ +ENTRY(__hyp_set_vectors) + mov r1, r0 + mov r0, #HVC_SET_VECTORS + __HVC(0) + ret lr +ENDPROC(__hyp_set_vectors) + +ENTRY(__hyp_soft_restart) + mov r1, r0 + mov r0, #HVC_SOFT_RESTART + __HVC(0) + ret lr +ENDPROC(__hyp_soft_restart) + +#ifndef ZIMAGE +.align 2 +.L__boot_cpu_mode_offset: + .long __boot_cpu_mode - . +#endif + +.align 5 +ENTRY(__hyp_stub_vectors) +__hyp_stub_reset: W(b) . +__hyp_stub_und: W(b) . +__hyp_stub_svc: W(b) . +__hyp_stub_pabort: W(b) . +__hyp_stub_dabort: W(b) . +__hyp_stub_trap: W(b) __hyp_stub_do_trap +__hyp_stub_irq: W(b) . +__hyp_stub_fiq: W(b) . +ENDPROC(__hyp_stub_vectors) + |