On 24/11/15 22:25, Geoff Levand wrote:
> Commit 68234df4ea7939f98431aa81113fbdce10c4a84b (arm64: kill
> flush_cache_all())
> removed the global arm64 routines cpu_reset() and cpu_soft_restart() needed by
> the arm64 kexec and kdump support. Add simplified versions of those two
> routines back with some changes needed for kexec in the new files cpu_reset.S,
> and cpu_reset.h.
>
> 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
> which signals if the reset address needs to be entered at EL1 or EL2.
>
> Signed-off-by: Geoff Levand <[email protected]>
> ---
> arch/arm64/kernel/cpu-reset.S | 84
> +++++++++++++++++++++++++++++++++++++++++++
> arch/arm64/kernel/cpu-reset.h | 22 ++++++++++++
> 2 files changed, 106 insertions(+)
> create mode 100644 arch/arm64/kernel/cpu-reset.S
> create mode 100644 arch/arm64/kernel/cpu-reset.h
>
> diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
> new file mode 100644
> index 0000000..0423f27
> --- /dev/null
> +++ b/arch/arm64/kernel/cpu-reset.S
> @@ -0,0 +1,84 @@
> +/*
> + * cpu reset routines
> + *
> + * Copyright (C) 2001 Deep Blue Solutions Ltd.
> + * Copyright (C) 2012 ARM Ltd.
> + * Copyright (C) 2015 Huawei Futurewei Technologies.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/linkage.h>
> +#include <asm/assembler.h>
> +#include <asm/virt.h>
> +
> +#define SCTLR_ELx_I (1 << 12)
> +#define SCTLR_ELx_SA (1 << 3)
> +#define SCTLR_ELx_C (1 << 2)
> +#define SCTLR_ELx_A (1 << 1)
> +#define SCTLR_ELx_M 1
kvm_arm.h already has some of these defined, and sysreg.h has another
bunch. Can you please consolidate this into a single place (probably
sysreg.h)?
> +#define SCTLR_ELx_FLAGS (SCTLR_ELx_M | SCTLR_ELx_A | SCTLR_ELx_C |
> \
> + SCTLR_ELx_SA | SCTLR_ELx_I)
> +
> +.text
> +.pushsection .idmap.text, "ax"
> +
> +.align 5
Why is this .align directive required?
> +
> +/*
> + * cpu_soft_restart(cpu_reset, el2_switch, entry, arg0, arg1) - 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.
> + * @entry: Location to jump to for soft reset, passed to cpu_reset.
> + * arg0: First argument passed to @entry.
> + * arg1: Second argument passed to @entry.
> + */
> +
> +ENTRY(cpu_soft_restart)
> + mov x18, x0 // cpu_reset
> + mov x0, x1 // el2_switch
> + mov x1, x2 // entry
> + mov x2, x3 // arg0
> + mov x3, x4 // arg1
> + ret x18
> +ENDPROC(cpu_soft_restart)
Grepping through the tree, I can only find a single use of
cpu_soft_restart, with cpu_reset as its first parameter.
Why do we need this indirection? Having
void cpu_soft_restart(el2_switch, entry, arg0, arg1);
should be enough...
> +
> +/*
> + * cpu_reset(el2_switch, entry, arg0, arg1) - Helper for cpu_soft_restart.
> + *
> + * @el2_switch: Flag to indicate a swich to EL2 is needed.
> + * @entry: Location to jump to for soft reset.
> + * arg0: First argument passed to @entry.
> + * arg1: Second argument passed to @entry.
> + *
> + * 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.
> + */
> +
> +ENTRY(cpu_reset)
> + /* Clear sctlr_el1 flags. */
> + mrs x12, sctlr_el1
> + ldr x13, =SCTLR_ELx_FLAGS
> + bic x12, x12, x13
> + msr sctlr_el1, x12
> + isb
> +
> + cbz x0, 1f // el2_switch?
> +
> + mov x0, x1 // entry
> + mov x1, x2 // arg0
> + mov x2, x3 // arg1
> + hvc #HVC_CALL_FUNC // no return
> +
> +1: mov x18, x1 // entry
> + mov x0, x2 // arg0
> + mov x1, x3 // arg1
> + ret x18
> +ENDPROC(cpu_reset)
And this can be an actual part of cpu_soft_reset.
> +
> +.popsection
> diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h
> new file mode 100644
> index 0000000..79816b6
> --- /dev/null
> +++ b/arch/arm64/kernel/cpu-reset.h
> @@ -0,0 +1,22 @@
> +/*
> + * cpu reset routines
> + *
> + * Copyright (C) 2015 Huawei Futurewei Technologies.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#if !defined(_ARM64_CPU_RESET_H)
The usual idiom is "#ifndef __BLAH_H".
> +#define _ARM64_CPU_RESET_H
> +
> +#include <asm/virt.h>
> +
> +void __attribute__((noreturn)) cpu_reset(unsigned long el2_switch,
> + unsigned long entry, unsigned long arg0, unsigned long arg1);
> +void __attribute__((noreturn)) cpu_soft_restart(phys_addr_t cpu_reset,
> + unsigned long el2_switch, unsigned long entry, unsigned long arg0,
> + unsigned long arg1);
> +
> +#endif
>
There is a __noreturn attribute already defined.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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