s390/kexec_file: Add kexec_file_load system call (71406883) · Commits · e / devices / android_kernel_fairphone_FP5

arch/s390/Kconfig

+13 −0

Original line number	Diff line number	Diff line
		@@ -51,6 +51,19 @@ config KEXEC
		def_bool y
		select KEXEC_CORE

		config KEXEC_FILE
		bool "kexec file based system call"
		select KEXEC_CORE
		select BUILD_BIN2C
		depends on CRYPTO
		depends on CRYPTO_SHA256
		depends on CRYPTO_SHA256_S390
		---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 ARCH_HAS_KEXEC_PURGATORY
		def_bool y
		depends on KEXEC_FILE

arch/s390/configs/default_defconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -719,3 +719,4 @@ CONFIG_APPLDATA_BASE=y
		CONFIG_KVM=m
		CONFIG_KVM_S390_UCONTROL=y
		CONFIG_VHOST_NET=m
		CONFIG_KEXEC_FILE=y

arch/s390/kernel/Makefile

+2 −0

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		@@ -82,6 +82,8 @@ obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o
		obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
		obj-$(CONFIG_UPROBES) += uprobes.o

		obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file.o

		obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_cpum_cf.o perf_cpum_sf.o
		obj-$(CONFIG_PERF_EVENTS) += perf_cpum_cf_events.o perf_regs.o

arch/s390/kernel/compat_wrapper.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -182,3 +182,4 @@ COMPAT_SYSCALL_WRAP6(copy_file_range, int, fd_in, loff_t __user *, off_in, int,
		COMPAT_SYSCALL_WRAP2(s390_guarded_storage, int, command, struct gs_cb *, gs_cb);
		COMPAT_SYSCALL_WRAP5(statx, int, dfd, const char __user , path, unsigned, flags, unsigned, mask, struct statx __user , buffer);
		COMPAT_SYSCALL_WRAP4(s390_sthyi, unsigned long, code, void __user , info, u64 __user , rc, unsigned long, flags);
		COMPAT_SYSCALL_WRAP5(kexec_file_load, int, kernel_fd, int, initrd_fd, unsigned long, cmdline_len, const char __user *, cmdline_ptr, unsigned long, flags)

arch/s390/kernel/machine_kexec_file.c

0 → 100644

+126 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		/*
		* s390 code for kexec_file_load system call
		*
		* Copyright IBM Corp. 2018
		*
		* Author(s): Philipp Rudo <prudo@linux.vnet.ibm.com>
		*/

		#include <linux/elf.h>
		#include <linux/kexec.h>
		#include <asm/setup.h>

		const struct kexec_file_ops * const kexec_file_loaders[] = {
		NULL,
		};

		/*
		* The kernel is loaded to a fixed location. Turn off kexec_locate_mem_hole
		* and provide kbuf->mem by hand.
		*/
		int arch_kexec_walk_mem(struct kexec_buf *kbuf,
		int (func)(struct resource , void *))
		{
		return 1;
		}

		int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
		Elf_Shdr *section,
		const Elf_Shdr *relsec,
		const Elf_Shdr *symtab)
		{
		Elf_Rela *relas;
		int i;

		relas = (void *)pi->ehdr + relsec->sh_offset;

		for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
		const Elf_Sym sym; / symbol to relocate */
		unsigned long addr; /* final location after relocation */
		unsigned long val; /* relocated symbol value */
		void loc; / tmp location to modify */

		sym = (void *)pi->ehdr + symtab->sh_offset;
		sym += ELF64_R_SYM(relas[i].r_info);

		if (sym->st_shndx == SHN_UNDEF)
		return -ENOEXEC;

		if (sym->st_shndx == SHN_COMMON)
		return -ENOEXEC;

		if (sym->st_shndx >= pi->ehdr->e_shnum &&
		sym->st_shndx != SHN_ABS)
		return -ENOEXEC;

		loc = pi->purgatory_buf;
		loc += section->sh_offset;
		loc += relas[i].r_offset;

		val = sym->st_value;
		if (sym->st_shndx != SHN_ABS)
		val += pi->sechdrs[sym->st_shndx].sh_addr;
		val += relas[i].r_addend;

		addr = section->sh_addr + relas[i].r_offset;

		switch (ELF64_R_TYPE(relas[i].r_info)) {
		case R_390_8: /* Direct 8 bit. */
		(u8 )loc = val;
		break;
		case R_390_12: /* Direct 12 bit. */
		(u16 )loc &= 0xf000;
		(u16 )loc \|= val & 0xfff;
		break;
		case R_390_16: /* Direct 16 bit. */
		(u16 )loc = val;
		break;
		case R_390_20: /* Direct 20 bit. */
		(u32 )loc &= 0xf00000ff;
		(u32 )loc \|= (val & 0xfff) << 16; /* DL */
		(u32 )loc \|= (val & 0xff000) >> 4; /* DH */
		break;
		case R_390_32: /* Direct 32 bit. */
		(u32 )loc = val;
		break;
		case R_390_64: /* Direct 64 bit. */
		(u64 )loc = val;
		break;
		case R_390_PC16: /* PC relative 16 bit. */
		(u16 )loc = (val - addr);
		break;
		case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
		(u16 )loc = (val - addr) >> 1;
		break;
		case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
		(u32 )loc = (val - addr) >> 1;
		break;
		case R_390_PC32: /* PC relative 32 bit. */
		(u32 )loc = (val - addr);
		break;
		case R_390_PC64: /* PC relative 64 bit. */
		(u64 )loc = (val - addr);
		break;
		default:
		break;
		}
		}
		return 0;
		}

		int arch_kexec_kernel_image_probe(struct kimage image, void buf,
		unsigned long buf_len)
		{
		/* A kernel must be at least large enough to contain head.S. During
		* load memory in head.S will be accessed, e.g. to register the next
		* command line. If the next kernel were smaller the current kernel
		* will panic at load.
		*
		* 0x11000 = sizeof(head.S)
		*/
		if (buf_len < 0x11000)
		return -ENOEXEC;

		return kexec_image_probe_default(image, buf, buf_len);
		}