[PATCH 4/4] parisc: add support for kexec_file_load() syscall

[Sven Schnelle <svens@stackframe.org>]

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 arch/parisc/Kconfig             | 10 ++++
 arch/parisc/kernel/Makefile     |  1 +
 arch/parisc/kernel/kexec.c      |  7 +++
 arch/parisc/kernel/kexec_file.c | 86 +++++++++++++++++++++++++++++++++
 4 files changed, 104 insertions(+)
 create mode 100644 arch/parisc/kernel/kexec_file.c

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 548c767f4358..2e757c785239 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -359,6 +359,16 @@ config KEXEC
 	  shutdown, so do not be surprised if this code does not
 	  initially work for you.
 
+config KEXEC_FILE
+	bool "kexec file based system call"
+	select KEXEC_CORE
+	select KEXEC_ELF
+	help
+	  This enables the kexec_file_load() System call. This 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.
+
 endmenu
 
 
diff --git a/arch/parisc/kernel/Makefile b/arch/parisc/kernel/Makefile
index 487cf88866a8..2663c8f8be11 100644
--- a/arch/parisc/kernel/Makefile
+++ b/arch/parisc/kernel/Makefile
@@ -38,3 +38,4 @@ obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
 obj-$(CONFIG_KGDB)			+= kgdb.o
 obj-$(CONFIG_KPROBES)			+= kprobes.o
 obj-$(CONFIG_KEXEC)			+= kexec.o relocate_kernel.o
+obj-$(CONFIG_KEXEC_FILE)		+= kexec_file.o
diff --git a/arch/parisc/kernel/kexec.c b/arch/parisc/kernel/kexec.c
index deeb0466d359..3d0716ded552 100644
--- a/arch/parisc/kernel/kexec.c
+++ b/arch/parisc/kernel/kexec.c
@@ -37,6 +37,13 @@ static void kexec_image_info(const struct kimage *kimage)
 
 	for (i = 0; i < kimage->nr_segments; i++)
 		kexec_show_segment_info(kimage, i);
+
+#ifdef CONFIG_KEXEC_FILE
+	if (kimage->file_mode) {
+		pr_debug("cmdline: %.*s\n", (int)kimage->cmdline_buf_len,
+			 kimage->cmdline_buf);
+	}
+#endif
 }
 
 void machine_kexec_cleanup(struct kimage *kimage)
diff --git a/arch/parisc/kernel/kexec_file.c b/arch/parisc/kernel/kexec_file.c
new file mode 100644
index 000000000000..f87c26e5e735
--- /dev/null
+++ b/arch/parisc/kernel/kexec_file.c
@@ -0,0 +1,86 @@
+/*
+ * Load ELF vmlinux file for the kexec_file_load syscall.
+ *
+ * Copyright (c) 2019 Sven Schnelle <svens@stackframe.org>
+ *
+ */
+#include <linux/elf.h>
+#include <linux/kexec.h>
+#include <linux/libfdt.h>
+#include <linux/module.h>
+#include <linux/of_fdt.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+static void *elf_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, i;
+	unsigned long kernel_load_addr;
+	struct elfhdr ehdr;
+	struct kexec_elf_info elf_info;
+	struct kexec_buf kbuf = { .image = image, .buf_min = 0,
+				  .buf_max = -1UL, };
+
+	ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
+	if (ret)
+		goto out;
+
+	ret = kexec_elf_load(image, &ehdr, &elf_info, &kbuf, &kernel_load_addr);
+	if (ret)
+		goto out;
+
+	image->start = __pa(elf_info.ehdr->e_entry);
+
+	for(i = 0; i < image->nr_segments; i++)
+		image->segment[i].mem = __pa(image->segment[i].mem);
+
+	pr_debug("Loaded the kernel at 0x%lx, entry at 0x%lx\n",
+		 kernel_load_addr, image->start);
+
+	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;
+
+		pr_debug("Loaded initrd at 0x%lx\n", kbuf.mem);
+		image->arch.initrd_start = kbuf.mem;
+		image->arch.initrd_end = kbuf.mem + initrd_len;
+	}
+
+	if (cmdline != NULL) {
+		kbuf.buffer = cmdline;
+		kbuf.bufsz = kbuf.memsz = ALIGN(cmdline_len, 8);
+		kbuf.buf_align = PAGE_SIZE;
+		kbuf.top_down = false;
+		kbuf.buf_min = PAGE0->mem_free + PAGE_SIZE;
+		kbuf.buf_max = kernel_load_addr;
+		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+		ret = kexec_add_buffer(&kbuf);
+		if (ret)
+			goto out;
+
+		pr_debug("Loaded cmdline at 0x%lx\n", kbuf.mem);
+		image->arch.cmdline = kbuf.mem;
+	}
+out:
+	return NULL;
+}
+
+const struct kexec_file_ops kexec_elf_ops = {
+	.probe = kexec_elf_probe,
+	.load = elf_load,
+};
+
+const struct kexec_file_ops * const kexec_file_loaders[] = {
+	&kexec_elf_ops,
+	NULL
+};
+
-- 
2.23.0.rc1