diff options
| -rw-r--r-- | arch/arm/include/asm/assembler.h | 28 | ||||
| -rw-r--r-- | arch/arm/include/asm/ptrace.h | 1 | ||||
| -rw-r--r-- | arch/arm/include/asm/virt.h | 52 | ||||
| -rw-r--r-- | arch/arm/kernel/Makefile | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/head.S | 14 | ||||
| -rw-r--r-- | arch/arm/kernel/hyp-stub.S | 192 |
6 files changed, 286 insertions, 3 deletions
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index 03fb936..658a15d 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -22,6 +22,7 @@ #include <asm/ptrace.h> #include <asm/domain.h> +#include <asm/opcodes-virt.h> #define IOMEM(x) (x) @@ -240,6 +241,33 @@ #endif /* + * Helper macro to enter SVC mode cleanly and mask interrupts. reg is + * a scratch register for the macro to overwrite. + * + * This macro is intended for forcing the CPU into SVC mode at boot time. + * you cannot return to the original mode. + * + * Beware, it also clobers LR. + */ +.macro safe_svcmode_maskall reg:req + mrs \reg , cpsr + mov lr , \reg + and lr , lr , #MODE_MASK + cmp lr , #HYP_MODE + orr \reg , \reg , #PSR_A_BIT | PSR_I_BIT | PSR_F_BIT + bic \reg , \reg , #MODE_MASK + orr \reg , \reg , #SVC_MODE +THUMB( orr \reg , \reg , #PSR_T_BIT ) + msr spsr_cxsf, \reg + adr lr, BSYM(2f) + bne 1f + __MSR_ELR_HYP(14) + __ERET +1: movs pc, lr +2: +.endm + +/* * STRT/LDRT access macros with ARM and Thumb-2 variants */ #ifdef CONFIG_THUMB2_KERNEL diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h index 355ece5..91ef6c2 100644 --- a/arch/arm/include/asm/ptrace.h +++ b/arch/arm/include/asm/ptrace.h @@ -44,6 +44,7 @@ #define IRQ_MODE 0x00000012 #define SVC_MODE 0x00000013 #define ABT_MODE 0x00000017 +#define HYP_MODE 0x0000001a #define UND_MODE 0x0000001b #define SYSTEM_MODE 0x0000001f #define MODE32_BIT 0x00000010 diff --git a/arch/arm/include/asm/virt.h b/arch/arm/include/asm/virt.h new file mode 100644 index 0000000..0a99723e --- /dev/null +++ b/arch/arm/include/asm/virt.h @@ -0,0 +1,52 @@ +/* + * Copyright (c) 2012 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#ifndef VIRT_H +#define VIRT_H + +#include <asm/ptrace.h> + +/* + * Flag indicating that the kernel was not entered in the same mode on every + * CPU. The zImage loader stashes this value in an SPSR, so we need an + * architecturally defined flag bit here (the N flag, as it happens) + */ +#define BOOT_CPU_MODE_MISMATCH (1<<31) + +#ifndef __ASSEMBLY__ + +#ifdef CONFIG_ARM_VIRT_EXT +/* + * __boot_cpu_mode records what mode the primary CPU was booted in. + * A correctly-implemented bootloader must start all CPUs in the same mode: + * if it fails to do this, the flag BOOT_CPU_MODE_MISMATCH is set to indicate + * that some CPU(s) were booted in a different mode. + * + * This allows the kernel to flag an error when the secondaries have come up. + */ +extern int __boot_cpu_mode; + +void __hyp_set_vectors(unsigned long phys_vector_base); +unsigned long __hyp_get_vectors(void); +#else +#define __boot_cpu_mode (SVC_MODE) +#endif + +#endif /* __ASSEMBLY__ */ + +#endif /* ! VIRT_H */ diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 7ad2d5c..49b61a3 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -82,4 +82,6 @@ head-y := head$(MMUEXT).o obj-$(CONFIG_DEBUG_LL) += debug.o obj-$(CONFIG_EARLY_PRINTK) += early_printk.o +obj-$(CONFIG_ARM_VIRT_EXT) += hyp-stub.o + extra-y := $(head-y) vmlinux.lds diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index 3db960e..27093e4 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -83,8 +83,12 @@ ENTRY(stext) THUMB( .thumb ) @ switch to Thumb now. THUMB(1: ) - setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode - @ and irqs disabled +#ifdef CONFIG_ARM_VIRT_EXT + bl __hyp_stub_install +#endif + @ ensure svc mode and all interrupts masked + safe_svcmode_maskall r9 + mrc p15, 0, r9, c0, c0 @ get processor id bl __lookup_processor_type @ r5=procinfo r9=cpuid movs r10, r5 @ invalid processor (r5=0)? @@ -326,7 +330,11 @@ ENTRY(secondary_startup) * the processor type - there is no need to check the machine type * as it has already been validated by the primary processor. */ - setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 +#ifdef CONFIG_ARM_VIRT_EXT + bl __hyp_stub_install +#endif + safe_svcmode_maskall r9 + mrc p15, 0, r9, c0, c0 @ get processor id bl __lookup_processor_type movs r10, r5 @ invalid processor? diff --git a/arch/arm/kernel/hyp-stub.S b/arch/arm/kernel/hyp-stub.S new file mode 100644 index 0000000..b03e924 --- /dev/null +++ b/arch/arm/kernel/hyp-stub.S @@ -0,0 +1,192 @@ +/* + * Copyright (c) 2012 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#include <linux/init.h> +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/virt.h> + +/* + * 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 +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 r7, r7, #BOOT_CPU_MODE_MISMATCH + strne r7, [r5, r6] @ record what happened and give up + .endm + +/* + * 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 + bxne 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 + bxne 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. + */ + @ Now install the hypervisor stub: + 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 +#ifdef CONFIG_CPU_BIG_ENDIAN + orr r7, #(1 << 9) @ HSCTLR.EE +#endif + 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 + + bic r7, r4, #MODE_MASK + orr r7, r7, #SVC_MODE +THUMB( orr r7, r7, #PSR_T_BIT ) + msr spsr_cxsf, r7 @ This is SPSR_hyp. + + __MSR_ELR_HYP(14) @ msr elr_hyp, lr + __ERET @ return, switching to SVC mode + @ The boot CPU mode is left in r4. +ENDPROC(__hyp_stub_install_secondary) + +__hyp_stub_do_trap: + cmp r0, #-1 + mrceq p15, 4, r0, c12, c0, 0 @ get HVBAR + mcrne p15, 4, r0, c12, c0, 0 @ set HVBAR + __ERET +ENDPROC(__hyp_stub_do_trap) + +/* + * __hyp_set_vectors: Call this after boot to set the initial hypervisor + * vectors as part of hypervisor installation. On an SMP system, this should + * be called on each CPU. + * + * r0 must be the physical address of the new vector table (which must lie in + * the bottom 4GB of physical address space. + * + * r0 must be 32-byte aligned. + * + * Before calling this, you must check that the stub hypervisor is installed + * everywhere, by waiting for any secondary CPUs to be brought up and then + * checking that BOOT_CPU_MODE_HAVE_HYP(__boot_cpu_mode) is true. + * + * If not, there is a pre-existing hypervisor, some CPUs failed to boot, or + * something else went wrong... in such cases, trying to install a new + * hypervisor is unlikely to work as desired. + * + * When you call into your shiny new hypervisor, sp_hyp will contain junk, + * so you will need to set that to something sensible at the new hypervisor's + * initialisation entry point. + */ +ENTRY(__hyp_get_vectors) + mov r0, #-1 +ENDPROC(__hyp_get_vectors) + @ fall through +ENTRY(__hyp_set_vectors) + __HVC(0) + bx lr +ENDPROC(__hyp_set_vectors) + +.align 2 +.L__boot_cpu_mode_offset: + .long __boot_cpu_mode - . + +.align 5 +__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) + |
