arm64: Add back cpu reset routines

Commit 68234df4ea79 ("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 back a simplified version of
cpu_soft_restart() 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_soft_restart() to accept an argument
which signals if the reset address should be entered at EL1 or EL2, and
add a new hypercall HVC_SOFT_RESTART which is used for the EL2 switch.

Signed-off-by: Geoff Levand <geoff@infradead.org>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index dcbcf8dcbefbf7a41542941dcad3c3950bb9da2e..bbc6a8cf83f1f5e123b309e31f3bf9ff6445fb43 100644 (file)
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -34,6 +34,11 @@
  */
 #define HVC_SET_VECTORS 1
 
+/*
+ * HVC_SOFT_RESTART - CPU soft reset, used by the cpu_soft_restart routine.
+ */
+#define HVC_SOFT_RESTART 2
+
 #define BOOT_CPU_MODE_EL1      (0xe11)
 #define BOOT_CPU_MODE_EL2      (0xe12)
 

diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
new file mode 100644 (file)
index 0000000..65f42d2
--- /dev/null
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -0,0 +1,54 @@
+/*
+ * 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/sysreg.h>
+#include <asm/virt.h>
+
+.text
+.pushsection    .idmap.text, "ax"
+
+/*
+ * __cpu_soft_restart(el2_switch, entry, arg0, arg1, arg2) - 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.
+ * arg2: Third 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_soft_restart)
+       /* 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, #HVC_SOFT_RESTART
+       hvc     #0                              // no return
+
+1:     mov     x18, x1                         // entry
+       mov     x0, x2                          // arg0
+       mov     x1, x3                          // arg1
+       mov     x2, x4                          // arg2
+       br      x18
+ENDPROC(__cpu_soft_restart)
+
+.popsection

diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h
new file mode 100644 (file)
index 0000000..d4e9ecb
--- /dev/null
+++ b/arch/arm64/kernel/cpu-reset.h
@@ -0,0 +1,34 @@
+/*
+ * 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.
+ */
+
+#ifndef _ARM64_CPU_RESET_H
+#define _ARM64_CPU_RESET_H
+
+#include <asm/virt.h>
+
+void __cpu_soft_restart(unsigned long el2_switch, unsigned long entry,
+       unsigned long arg0, unsigned long arg1, unsigned long arg2);
+
+static inline void __noreturn cpu_soft_restart(unsigned long el2_switch,
+       unsigned long entry, unsigned long arg0, unsigned long arg1,
+       unsigned long arg2)
+{
+       typeof(__cpu_soft_restart) *restart;
+
+       el2_switch = el2_switch && !is_kernel_in_hyp_mode() &&
+               is_hyp_mode_available();
+       restart = (void *)virt_to_phys(__cpu_soft_restart);
+
+       cpu_install_idmap();
+       restart(el2_switch, entry, arg0, arg1, arg2);
+       unreachable();
+}
+
+#endif

diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 8727f44907725445efd25735b9638672a2599cb0..d3b5f75e652efce050f8c0c7d5cdef69e0351dfd 100644 (file)
--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -71,8 +71,16 @@ el1_sync:
        msr     vbar_el2, x1
        b       9f
 
+2:     cmp     x0, #HVC_SOFT_RESTART
+       b.ne    3f
+       mov     x0, x2
+       mov     x2, x4
+       mov     x4, x1
+       mov     x1, x3
+       br      x4                              // no return
+
        /* Someone called kvm_call_hyp() against the hyp-stub... */
-2:     mov     x0, #ARM_EXCEPTION_HYP_GONE
+3:     mov     x0, #ARM_EXCEPTION_HYP_GONE
 
 9:     eret
 ENDPROC(el1_sync)