On Fri, Oct 24, 2014 at 12:10:58AM +0100, Geoff Levand wrote:
> When a CPU is reset it needs to be put into the exception level it had when it
> entered the kernel. Update cpu_reset() to accept an argument el2_switch which
> signals cpu_reset() to enter the soft reset address at EL2. If el2_switch is
> not set the soft reset address will be entered at EL1.
>
> Update cpu_soft_restart() and soft_restart() to pass the return of
> is_hyp_mode_available() as the el2_switch value to cpu_reset(). Also update the
> comments of cpu_reset(), cpu_soft_restart() and soft_restart() to reflect this
> change.
This will blow up without warning with KVM, and I think we need to
address that first.
Mark.
> Signed-off-by: Geoff Levand <geoff at infradead.org>
> ---
> arch/arm64/include/asm/proc-fns.h | 4 ++--
> arch/arm64/kernel/process.c | 6 ++++-
> arch/arm64/mm/proc.S | 47 +++++++++++++++++++++++++++++----------
> 3 files changed, 42 insertions(+), 15 deletions(-)
>
> diff --git a/arch/arm64/include/asm/proc-fns.h b/arch/arm64/include/asm/proc-fns.h
> index 9a8fd84..339394d 100644
> --- a/arch/arm64/include/asm/proc-fns.h
> +++ b/arch/arm64/include/asm/proc-fns.h
> @@ -32,8 +32,8 @@ extern void cpu_cache_off(void);
> extern void cpu_do_idle(void);
> extern void cpu_do_switch_mm(unsigned long pgd_phys, struct mm_struct *mm);
> extern void cpu_reset(unsigned long addr) __attribute__((noreturn));
> -void cpu_soft_restart(phys_addr_t cpu_reset,
> - unsigned long addr) __attribute__((noreturn));
> +void cpu_soft_restart(phys_addr_t cpu_reset, unsigned long el2_switch,
> + unsigned long addr) __attribute__((noreturn));
> extern void cpu_do_suspend(struct cpu_suspend_ctx *ptr);
> extern u64 cpu_do_resume(phys_addr_t ptr, u64 idmap_ttbr);
>
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index bf66922..0a3414b 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -50,6 +50,7 @@
> #include <asm/mmu_context.h>
> #include <asm/processor.h>
> #include <asm/stacktrace.h>
> +#include <asm/virt.h>
>
> #ifdef CONFIG_CC_STACKPROTECTOR
> #include <linux/stackprotector.h>
> @@ -60,7 +61,10 @@ EXPORT_SYMBOL(__stack_chk_guard);
> void soft_restart(unsigned long addr)
> {
> setup_mm_for_reboot();
> - cpu_soft_restart(virt_to_phys(cpu_reset), addr);
> +
> + cpu_soft_restart(virt_to_phys(cpu_reset), is_hyp_mode_available(),
> + addr);
> +
> /* Should never get here */
> BUG();
> }
> diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
> index 4e778b1..7467199 100644
> --- a/arch/arm64/mm/proc.S
> +++ b/arch/arm64/mm/proc.S
> @@ -25,6 +25,7 @@
> #include <asm/hwcap.h>
> #include <asm/pgtable-hwdef.h>
> #include <asm/pgtable.h>
> +#include <asm/virt.h>
>
> #include "proc-macros.S"
>
> @@ -59,27 +60,48 @@ ENTRY(cpu_cache_off)
> ENDPROC(cpu_cache_off)
>
> /*
> - * cpu_reset(loc)
> + * cpu_reset(el2_switch, loc) - Helper for cpu_soft_restart.
> *
> - * Perform a soft reset of the system. Put the CPU into the same state
> - * as it would be if it had been reset, and branch to what would be the
> - * reset vector. It must be executed with the flat identity mapping.
> + * @cpu_reset: Physical address of the cpu_reset routine.
> + * @el2_switch: Flag to indicate a swich to EL2 is needed.
> + * @addr: Location to jump to for soft reset.
> *
> - * - loc - location to jump to for soft reset
> + * Put the CPU into the same state as it would be if it had been reset, and
> + * branch to what would be the reset vector. It must be executed with the
> + * flat identity mapping.
> */
> +
> .align 5
> +
> ENTRY(cpu_reset)
> - mrs x1, sctlr_el1
> - bic x1, x1, #1
> - msr sctlr_el1, x1 // disable the MMU
> + mrs x2, sctlr_el1
> + bic x2, x2, #1
> + msr sctlr_el1, x2 // disable the MMU
> isb
> - ret x0
> +
> + cbz x0, 1f // el2_switch?
> + mov x0, x1
> + mov x1, xzr
> + mov x2, xzr
> + mov x3, xzr
> + hvc #HVC_CALL_FUNC // no return
> +
> +1: ret x1
> ENDPROC(cpu_reset)
>
> +/*
> + * cpu_soft_restart(cpu_reset, el2_switch, addr) - Perform a cpu soft reset.
> + *
> + * @cpu_reset: Physical address of the cpu_reset routine.
> + * @el2_switch: Flag to indicate a swich to EL2 is needed, passed to cpu_reset.
> + * @addr: Location to jump to for soft reset, passed to cpu_reset.
> + *
> + */
> +
> ENTRY(cpu_soft_restart)
> - /* Save address of cpu_reset() and reset address */
> - mov x19, x0
> - mov x20, x1
> + mov x19, x0 // cpu_reset
> + mov x20, x1 // el2_switch
> + mov x21, x2 // addr
>
> /* Turn D-cache off */
> bl cpu_cache_off
> @@ -88,6 +110,7 @@ ENTRY(cpu_soft_restart)
> bl flush_cache_all
>
> mov x0, x20
> + mov x1, x21
> ret x19
> ENDPROC(cpu_soft_restart)
>
> --
> 1.9.1
>
>
>
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