RISC-V: Add kexec support
This patch adds support for kexec on RISC-V. On SMP systems it depends on HOTPLUG_CPU in order to be able to bring up all harts after kexec. It also needs a recent OpenSBI version that supports the HSM extension. I tested it on riscv64 QEMU on both an smp and a non-smp system. Signed-off-by: Nick Kossifidis <mick@ics.forth.gr> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Nick Kossifidis
Palmer Dabbelt
parent
d83e682e30
commit
fba8a8674f
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@ -391,6 +391,21 @@ config RISCV_SBI_V01
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help
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This config allows kernel to use SBI v0.1 APIs. This will be
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deprecated in future once legacy M-mode software are no longer in use.
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config KEXEC
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bool "Kexec system call"
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select KEXEC_CORE
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select HOTPLUG_CPU if SMP
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depends on MMU
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help
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kexec is a system call that implements the ability to shutdown your
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current kernel, and to start another kernel. It is like a reboot
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but it is independent of the system firmware. And like a reboot
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you can start any kernel with it, not just Linux.
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The name comes from the similarity to the exec system call.
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endmenu
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menu "Boot options"
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@ -0,0 +1,49 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2019 FORTH-ICS/CARV
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* Nick Kossifidis <mick@ics.forth.gr>
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*/
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#ifndef _RISCV_KEXEC_H
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#define _RISCV_KEXEC_H
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#include <asm/page.h> /* For PAGE_SIZE */
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/* Maximum physical address we can use pages from */
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#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
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/* Maximum address we can reach in physical address mode */
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#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
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/* Maximum address we can use for the control code buffer */
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#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
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/* Reserve a page for the control code buffer */
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#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
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#define KEXEC_ARCH KEXEC_ARCH_RISCV
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static inline void
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crash_setup_regs(struct pt_regs *newregs,
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struct pt_regs *oldregs)
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{
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/* Dummy implementation for now */
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}
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#define ARCH_HAS_KIMAGE_ARCH
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struct kimage_arch {
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unsigned long fdt_addr;
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};
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const extern unsigned char riscv_kexec_relocate[];
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const extern unsigned int riscv_kexec_relocate_size;
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typedef void (*riscv_kexec_do_relocate)(unsigned long first_ind_entry,
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unsigned long jump_addr,
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unsigned long fdt_addr,
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unsigned long hartid,
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unsigned long va_pa_off);
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#endif
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@ -9,6 +9,10 @@ CFLAGS_REMOVE_patch.o = $(CC_FLAGS_FTRACE)
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CFLAGS_REMOVE_sbi.o = $(CC_FLAGS_FTRACE)
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endif
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ifdef CONFIG_KEXEC
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AFLAGS_kexec_relocate.o := -mcmodel=medany -mno-relax
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endif
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extra-y += head.o
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extra-y += vmlinux.lds
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@ -54,6 +58,7 @@ obj-$(CONFIG_SMP) += cpu_ops_sbi.o
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endif
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obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
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obj-$(CONFIG_KGDB) += kgdb.o
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obj-$(CONFIG_KEXEC) += kexec_relocate.o machine_kexec.o
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obj-$(CONFIG_JUMP_LABEL) += jump_label.o
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@ -0,0 +1,157 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2019 FORTH-ICS/CARV
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* Nick Kossifidis <mick@ics.forth.gr>
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*/
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#include <asm/asm.h> /* For RISCV_* and REG_* macros */
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#include <asm/csr.h> /* For CSR_* macros */
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#include <asm/page.h> /* For PAGE_SIZE */
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#include <linux/linkage.h> /* For SYM_* macros */
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.section ".rodata"
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SYM_CODE_START(riscv_kexec_relocate)
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/*
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* s0: Pointer to the current entry
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* s1: (const) Phys address to jump to after relocation
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* s2: (const) Phys address of the FDT image
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* s3: (const) The hartid of the current hart
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* s4: Pointer to the destination address for the relocation
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* s5: (const) Number of words per page
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* s6: (const) 1, used for subtraction
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* s7: (const) va_pa_offset, used when switching MMU off
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* s8: (const) Physical address of the main loop
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* s9: (debug) indirection page counter
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* s10: (debug) entry counter
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* s11: (debug) copied words counter
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*/
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mv s0, a0
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mv s1, a1
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mv s2, a2
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mv s3, a3
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mv s4, zero
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li s5, (PAGE_SIZE / RISCV_SZPTR)
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li s6, 1
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mv s7, a4
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mv s8, zero
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mv s9, zero
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mv s10, zero
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mv s11, zero
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/* Disable / cleanup interrupts */
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csrw CSR_SIE, zero
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csrw CSR_SIP, zero
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/*
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* When we switch SATP.MODE to "Bare" we'll only
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* play with physical addresses. However the first time
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* we try to jump somewhere, the offset on the jump
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* will be relative to pc which will still be on VA. To
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* deal with this we set stvec to the physical address at
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* the start of the loop below so that we jump there in
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* any case.
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*/
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la s8, 1f
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sub s8, s8, s7
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csrw CSR_STVEC, s8
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/* Process entries in a loop */
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.align 2
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1:
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addi s10, s10, 1
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REG_L t0, 0(s0) /* t0 = *image->entry */
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addi s0, s0, RISCV_SZPTR /* image->entry++ */
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/* IND_DESTINATION entry ? -> save destination address */
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andi t1, t0, 0x1
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beqz t1, 2f
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andi s4, t0, ~0x1
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j 1b
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2:
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/* IND_INDIRECTION entry ? -> update next entry ptr (PA) */
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andi t1, t0, 0x2
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beqz t1, 2f
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andi s0, t0, ~0x2
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addi s9, s9, 1
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csrw CSR_SATP, zero
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jalr zero, s8, 0
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2:
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/* IND_DONE entry ? -> jump to done label */
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andi t1, t0, 0x4
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beqz t1, 2f
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j 4f
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2:
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/*
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* IND_SOURCE entry ? -> copy page word by word to the
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* destination address we got from IND_DESTINATION
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*/
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andi t1, t0, 0x8
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beqz t1, 1b /* Unknown entry type, ignore it */
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andi t0, t0, ~0x8
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mv t3, s5 /* i = num words per page */
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3: /* copy loop */
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REG_L t1, (t0) /* t1 = *src_ptr */
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REG_S t1, (s4) /* *dst_ptr = *src_ptr */
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addi t0, t0, RISCV_SZPTR /* stc_ptr++ */
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addi s4, s4, RISCV_SZPTR /* dst_ptr++ */
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sub t3, t3, s6 /* i-- */
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addi s11, s11, 1 /* c++ */
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beqz t3, 1b /* copy done ? */
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j 3b
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4:
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/* Pass the arguments to the next kernel / Cleanup*/
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mv a0, s3
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mv a1, s2
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mv a2, s1
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/* Cleanup */
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mv a3, zero
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mv a4, zero
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mv a5, zero
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mv a6, zero
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mv a7, zero
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mv s0, zero
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mv s1, zero
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mv s2, zero
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mv s3, zero
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mv s4, zero
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mv s5, zero
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mv s6, zero
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mv s7, zero
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mv s8, zero
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mv s9, zero
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mv s10, zero
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mv s11, zero
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mv t0, zero
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mv t1, zero
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mv t2, zero
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mv t3, zero
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mv t4, zero
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mv t5, zero
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mv t6, zero
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csrw CSR_SEPC, zero
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csrw CSR_SCAUSE, zero
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csrw CSR_SSCRATCH, zero
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/*
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* Make sure the relocated code is visible
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* and jump to the new kernel
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*/
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fence.i
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jalr zero, a2, 0
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SYM_CODE_END(riscv_kexec_relocate)
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riscv_kexec_relocate_end:
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.section ".rodata"
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SYM_DATA(riscv_kexec_relocate_size,
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.long riscv_kexec_relocate_end - riscv_kexec_relocate)
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@ -0,0 +1,186 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2019 FORTH-ICS/CARV
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* Nick Kossifidis <mick@ics.forth.gr>
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*/
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#include <linux/kexec.h>
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#include <asm/kexec.h> /* For riscv_kexec_* symbol defines */
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#include <linux/smp.h> /* For smp_send_stop () */
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#include <asm/cacheflush.h> /* For local_flush_icache_all() */
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#include <asm/barrier.h> /* For smp_wmb() */
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#include <asm/page.h> /* For PAGE_MASK */
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#include <linux/libfdt.h> /* For fdt_check_header() */
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#include <asm/set_memory.h> /* For set_memory_x() */
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#include <linux/compiler.h> /* For unreachable() */
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#include <linux/cpu.h> /* For cpu_down() */
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/**
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* kexec_image_info - Print received image details
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*/
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static void
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kexec_image_info(const struct kimage *image)
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{
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unsigned long i;
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pr_debug("Kexec image info:\n");
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pr_debug("\ttype: %d\n", image->type);
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pr_debug("\tstart: %lx\n", image->start);
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pr_debug("\thead: %lx\n", image->head);
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pr_debug("\tnr_segments: %lu\n", image->nr_segments);
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for (i = 0; i < image->nr_segments; i++) {
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pr_debug("\t segment[%lu]: %016lx - %016lx", i,
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image->segment[i].mem,
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image->segment[i].mem + image->segment[i].memsz);
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pr_debug("\t\t0x%lx bytes, %lu pages\n",
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(unsigned long) image->segment[i].memsz,
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(unsigned long) image->segment[i].memsz / PAGE_SIZE);
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}
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}
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/**
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* machine_kexec_prepare - Initialize kexec
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*
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* This function is called from do_kexec_load, when the user has
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* provided us with an image to be loaded. Its goal is to validate
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* the image and prepare the control code buffer as needed.
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* Note that kimage_alloc_init has already been called and the
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* control buffer has already been allocated.
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*/
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int
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machine_kexec_prepare(struct kimage *image)
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{
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struct kimage_arch *internal = &image->arch;
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struct fdt_header fdt = {0};
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void *control_code_buffer = NULL;
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unsigned int control_code_buffer_sz = 0;
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int i = 0;
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kexec_image_info(image);
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if (image->type == KEXEC_TYPE_CRASH) {
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pr_warn("Loading a crash kernel is unsupported for now.\n");
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return -EINVAL;
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}
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/* Find the Flattened Device Tree and save its physical address */
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for (i = 0; i < image->nr_segments; i++) {
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if (image->segment[i].memsz <= sizeof(fdt))
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continue;
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if (copy_from_user(&fdt, image->segment[i].buf, sizeof(fdt)))
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continue;
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if (fdt_check_header(&fdt))
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continue;
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internal->fdt_addr = (unsigned long) image->segment[i].mem;
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break;
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}
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if (!internal->fdt_addr) {
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pr_err("Device tree not included in the provided image\n");
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return -EINVAL;
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}
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/* Copy the assembler code for relocation to the control page */
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control_code_buffer = page_address(image->control_code_page);
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control_code_buffer_sz = page_size(image->control_code_page);
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if (unlikely(riscv_kexec_relocate_size > control_code_buffer_sz)) {
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pr_err("Relocation code doesn't fit within a control page\n");
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return -EINVAL;
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}
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memcpy(control_code_buffer, riscv_kexec_relocate,
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riscv_kexec_relocate_size);
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/* Mark the control page executable */
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set_memory_x((unsigned long) control_code_buffer, 1);
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return 0;
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}
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/**
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* machine_kexec_cleanup - Cleanup any leftovers from
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* machine_kexec_prepare
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*
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* This function is called by kimage_free to handle any arch-specific
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* allocations done on machine_kexec_prepare. Since we didn't do any
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* allocations there, this is just an empty function. Note that the
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* control buffer is freed by kimage_free.
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*/
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void
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machine_kexec_cleanup(struct kimage *image)
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{
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}
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/*
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* machine_shutdown - Prepare for a kexec reboot
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*
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* This function is called by kernel_kexec just before machine_kexec
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* below. Its goal is to prepare the rest of the system (the other
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* harts and possibly devices etc) for a kexec reboot.
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*/
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void machine_shutdown(void)
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{
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/*
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* No more interrupts on this hart
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* until we are back up.
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*/
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local_irq_disable();
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#if defined(CONFIG_HOTPLUG_CPU)
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smp_shutdown_nonboot_cpus(smp_processor_id());
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#endif
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}
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/**
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* machine_crash_shutdown - Prepare to kexec after a kernel crash
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*
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* This function is called by crash_kexec just before machine_kexec
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* below and its goal is similar to machine_shutdown, but in case of
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* a kernel crash. Since we don't handle such cases yet, this function
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* is empty.
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*/
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void
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machine_crash_shutdown(struct pt_regs *regs)
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{
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}
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/**
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* machine_kexec - Jump to the loaded kimage
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*
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* This function is called by kernel_kexec which is called by the
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* reboot system call when the reboot cmd is LINUX_REBOOT_CMD_KEXEC,
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* or by crash_kernel which is called by the kernel's arch-specific
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* trap handler in case of a kernel panic. It's the final stage of
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* the kexec process where the pre-loaded kimage is ready to be
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* executed. We assume at this point that all other harts are
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* suspended and this hart will be the new boot hart.
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*/
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void __noreturn
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machine_kexec(struct kimage *image)
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{
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struct kimage_arch *internal = &image->arch;
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unsigned long jump_addr = (unsigned long) image->start;
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unsigned long first_ind_entry = (unsigned long) &image->head;
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unsigned long this_hart_id = raw_smp_processor_id();
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unsigned long fdt_addr = internal->fdt_addr;
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void *control_code_buffer = page_address(image->control_code_page);
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riscv_kexec_do_relocate do_relocate = control_code_buffer;
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pr_notice("Will call new kernel at %08lx from hart id %lx\n",
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jump_addr, this_hart_id);
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pr_notice("FDT image at %08lx\n", fdt_addr);
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/* Make sure the relocation code is visible to the hart */
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local_flush_icache_all();
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/* Jump to the relocation code */
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pr_notice("Bye...\n");
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do_relocate(first_ind_entry, jump_addr, fdt_addr,
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this_hart_id, va_pa_offset);
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unreachable();
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}
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