[PATCH 3/3] RISC-V: Add kexec_file support
Liao Chang
liaochang1 at huawei.com
Fri Oct 29 20:18:32 PDT 2021
This patch adds support for kexec_file on RISC-V. I tested it on riscv64
QEMU with busybear-linux and single core along with the OpenSBI firmware
fw_jump.bin for generic platform.
On SMP system, it depends on CONFIG_{HOTPLUG_CPU, RISCV_SBI} to
resume/stop hart through OpenSBI firmware, it also needs a OpenSBI that
support the HSM extension.
Signed-off-by: Liao Chang <liaochang1 at huawei.com>
---
arch/riscv/Kconfig | 11 ++
arch/riscv/include/asm/kexec.h | 4 +
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/elf_kexec.c | 180 +++++++++++++++++++++++++
arch/riscv/kernel/machine_kexec_file.c | 14 ++
5 files changed, 210 insertions(+)
create mode 100644 arch/riscv/kernel/elf_kexec.c
create mode 100644 arch/riscv/kernel/machine_kexec_file.c
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 301a54233c7e..5ebe8272dec7 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -410,6 +410,17 @@ config KEXEC
The name comes from the similarity to the exec system call.
+config KEXEC_FILE
+ bool "kexec file based systmem call"
+ select KEXEC_CORE
+ select KEXEC_ELF
+ select HAVE_IMA_KEXEC if IMA
+ help
+ This is new version of kexec system call. This system call is
+ file based and takes file descriptors as system call argument
+ for kernel and initramfs as opposed to list of segments as
+ accepted by previous system call.
+
config CRASH_DUMP
bool "Build kdump crash kernel"
help
diff --git a/arch/riscv/include/asm/kexec.h b/arch/riscv/include/asm/kexec.h
index e4e291d40759..206217b23301 100644
--- a/arch/riscv/include/asm/kexec.h
+++ b/arch/riscv/include/asm/kexec.h
@@ -53,4 +53,8 @@ typedef void (*riscv_kexec_method)(unsigned long first_ind_entry,
extern riscv_kexec_method riscv_kexec_norelocate;
+#ifdef CONFIG_KEXEC_FILE
+extern const struct kexec_file_ops elf_kexec_ops;
+#endif
+
#endif
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 3397ddac1a30..8a27639d512a 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -60,6 +60,7 @@ endif
obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
obj-$(CONFIG_KGDB) += kgdb.o
obj-$(CONFIG_KEXEC) += kexec_relocate.o crash_save_regs.o machine_kexec.o
+obj-$(CONFIG_KEXEC_FILE) += elf_kexec.o machine_kexec_file.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o
diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c
new file mode 100644
index 000000000000..269be9f9edb8
--- /dev/null
+++ b/arch/riscv/kernel/elf_kexec.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Load ELF vmlinux file for the kexec_file_load syscall.
+ *
+ * Copyright (C) 2021 Huawei Technologies Co, Ltd.
+ *
+ * Author: Liao Chang (liaochang1 at huawei.com)
+ *
+ * Based on kexec-tools' kexec-elf-riscv.c, heavily modified
+ * for kernel.
+ */
+
+#define pr_fmt(fmt) "kexec_image: " fmt
+
+#include <linux/elf.h>
+#include <linux/kexec.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/libfdt.h>
+#include <linux/types.h>
+
+static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
+ struct kexec_elf_info *elf_info, unsigned long old_pbase,
+ unsigned long new_pbase)
+{
+ int i;
+ int ret = 0;
+ size_t size;
+ struct kexec_buf kbuf;
+ const struct elf_phdr *phdr;
+
+ kbuf.image = image;
+
+ for (i = 0; i < ehdr->e_phnum; i++) {
+ phdr = &elf_info->proghdrs[i];
+ if (phdr->p_type != PT_LOAD)
+ continue;
+
+ size = phdr->p_filesz;
+ if (size > phdr->p_memsz)
+ size = phdr->p_memsz;
+
+ kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
+ kbuf.bufsz = size;
+ kbuf.buf_align = phdr->p_align;
+ kbuf.mem = phdr->p_paddr - old_pbase + new_pbase;
+ kbuf.memsz = phdr->p_memsz;
+ kbuf.top_down = false;
+ ret = kexec_add_buffer(&kbuf);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+/*
+ * Go through the available phsyical memory regions and find one that hold
+ * an image of the specified size.
+ */
+static int elf_find_pbase(struct kimage *image, unsigned long kernel_len,
+ struct elfhdr *ehdr, struct kexec_elf_info *elf_info,
+ unsigned long *old_pbase, unsigned long *new_pbase)
+{
+ int i;
+ int ret;
+ struct kexec_buf kbuf;
+ const struct elf_phdr *phdr;
+ unsigned long lowest_paddr = ULONG_MAX;
+ unsigned long lowest_vaddr = ULONG_MAX;
+
+ for (i = 0; i < ehdr->e_phnum; i++) {
+ phdr = &elf_info->proghdrs[i];
+ if (phdr->p_type != PT_LOAD)
+ continue;
+
+ if (lowest_paddr > phdr->p_paddr)
+ lowest_paddr = phdr->p_paddr;
+
+ if (lowest_vaddr > phdr->p_vaddr)
+ lowest_vaddr = phdr->p_vaddr;
+ }
+
+ kbuf.image = image;
+ kbuf.buf_min = lowest_paddr;
+ kbuf.buf_max = ULONG_MAX;
+ kbuf.buf_align = PAGE_SIZE;
+ kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+ kbuf.memsz = ALIGN(kernel_len, PAGE_SIZE);
+ kbuf.top_down = false;
+ ret = arch_kexec_locate_mem_hole(&kbuf);
+ if (!ret) {
+ *old_pbase = lowest_paddr;
+ *new_pbase = kbuf.mem;
+ image->start = ehdr->e_entry - lowest_vaddr + kbuf.mem;
+ }
+ return ret;
+}
+
+static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
+ unsigned long kernel_len, char *initrd,
+ unsigned long initrd_len, char *cmdline,
+ unsigned long cmdline_len)
+{
+ int ret;
+ unsigned long old_kernel_pbase = ULONG_MAX;
+ unsigned long new_kernel_pbase = 0UL;
+ unsigned long initrd_pbase = 0UL;
+ void *fdt;
+ struct elfhdr ehdr;
+ struct kexec_buf kbuf;
+ struct kexec_elf_info elf_info;
+
+ ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
+ if (ret)
+ return ERR_PTR(ret);
+
+ ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
+ &old_kernel_pbase, &new_kernel_pbase);
+ if (ret)
+ goto out;
+ pr_notice("The entry point of kernel at 0x%lx\n", image->start);
+
+ /* Add the kernel binary to the image */
+ ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
+ old_kernel_pbase, new_kernel_pbase);
+ if (ret)
+ goto out;
+
+ kbuf.image = image;
+ kbuf.buf_min = new_kernel_pbase + kernel_len;
+ kbuf.buf_max = ULONG_MAX;
+ /* Add the initrd to the image */
+ if (initrd != NULL) {
+ kbuf.buffer = initrd;
+ kbuf.bufsz = kbuf.memsz = initrd_len;
+ kbuf.buf_align = PAGE_SIZE;
+ kbuf.top_down = false;
+ kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+ ret = kexec_add_buffer(&kbuf);
+ if (ret)
+ goto out;
+ initrd_pbase = kbuf.mem;
+ pr_notice("Loaded initrd at 0x%lx\n", initrd_pbase);
+ }
+
+ /* Add the DTB to the image */
+ fdt = of_kexec_alloc_and_setup_fdt(image, initrd_pbase,
+ initrd_len, cmdline, 0);
+ if (!fdt) {
+ pr_err("Error setting up the new device tree.\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ fdt_pack(fdt);
+ kbuf.buffer = fdt;
+ kbuf.bufsz = kbuf.memsz = fdt_totalsize(fdt);
+ kbuf.buf_align = PAGE_SIZE;
+ kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+ kbuf.top_down = true;
+ ret = kexec_add_buffer(&kbuf);
+ if (ret) {
+ pr_err("Error add DTB kbuf ret=%d\n", ret);
+ goto out_free_fdt;
+ }
+ pr_notice("Loaded device tree at 0x%lx\n", kbuf.mem);
+ goto out;
+
+out_free_fdt:
+ kvfree(fdt);
+out:
+ kexec_free_elf_info(&elf_info);
+ return ret ? ERR_PTR(ret) : NULL;
+}
+
+const struct kexec_file_ops elf_kexec_ops = {
+ .probe = kexec_elf_probe,
+ .load = elf_kexec_load,
+};
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
new file mode 100644
index 000000000000..b0bf8c1722c0
--- /dev/null
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * kexec_file for riscv, use vmlinux as the dump-capture kernel image.
+ *
+ * Copyright (C) 2021 Huawei Technologies Co, Ltd.
+ *
+ * Author: Liao Chang (liaochang1 at huawei.com)
+ */
+#include <linux/kexec.h>
+
+const struct kexec_file_ops * const kexec_file_loaders[] = {
+ &elf_kexec_ops,
+ NULL
+};
--
2.17.1
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