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-rw-r--r--arch/mips/kernel/relocate.c466
1 files changed, 466 insertions, 0 deletions
diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c
new file mode 100644
index 0000000000..58fc8d0894
--- /dev/null
+++ b/arch/mips/kernel/relocate.c
@@ -0,0 +1,466 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Support for Kernel relocation at boot time
+ *
+ * Copyright (C) 2015, Imagination Technologies Ltd.
+ * Authors: Matt Redfearn (matt.redfearn@mips.com)
+ */
+#include <asm/bootinfo.h>
+#include <asm/cacheflush.h>
+#include <asm/fw/fw.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+#include <asm/timex.h>
+#include <linux/elf.h>
+#include <linux/kernel.h>
+#include <linux/libfdt.h>
+#include <linux/of_fdt.h>
+#include <linux/panic_notifier.h>
+#include <linux/sched/task.h>
+#include <linux/start_kernel.h>
+#include <linux/string.h>
+#include <linux/printk.h>
+
+#define RELOCATED(x) ((void *)((long)x + offset))
+
+extern u32 _relocation_start[]; /* End kernel image / start relocation table */
+extern u32 _relocation_end[]; /* End relocation table */
+
+extern long __start___ex_table; /* Start exception table */
+extern long __stop___ex_table; /* End exception table */
+
+extern void __weak plat_fdt_relocated(void *new_location);
+
+/*
+ * This function may be defined for a platform to perform any post-relocation
+ * fixup necessary.
+ * Return non-zero to abort relocation
+ */
+int __weak plat_post_relocation(long offset)
+{
+ return 0;
+}
+
+static inline u32 __init get_synci_step(void)
+{
+ u32 res;
+
+ __asm__("rdhwr %0, $1" : "=r" (res));
+
+ return res;
+}
+
+static void __init sync_icache(void *kbase, unsigned long kernel_length)
+{
+ void *kend = kbase + kernel_length;
+ u32 step = get_synci_step();
+
+ do {
+ __asm__ __volatile__(
+ "synci 0(%0)"
+ : /* no output */
+ : "r" (kbase));
+
+ kbase += step;
+ } while (step && kbase < kend);
+
+ /* Completion barrier */
+ __sync();
+}
+
+static void __init apply_r_mips_64_rel(u32 *loc_new, long offset)
+{
+ *(u64 *)loc_new += offset;
+}
+
+static void __init apply_r_mips_32_rel(u32 *loc_new, long offset)
+{
+ *loc_new += offset;
+}
+
+static int __init apply_r_mips_26_rel(u32 *loc_orig, u32 *loc_new, long offset)
+{
+ unsigned long target_addr = (*loc_orig) & 0x03ffffff;
+
+ if (offset % 4) {
+ pr_err("Dangerous R_MIPS_26 REL relocation\n");
+ return -ENOEXEC;
+ }
+
+ /* Original target address */
+ target_addr <<= 2;
+ target_addr += (unsigned long)loc_orig & 0xf0000000;
+
+ /* Get the new target address */
+ target_addr += offset;
+
+ if ((target_addr & 0xf0000000) != ((unsigned long)loc_new & 0xf0000000)) {
+ pr_err("R_MIPS_26 REL relocation overflow\n");
+ return -ENOEXEC;
+ }
+
+ target_addr -= (unsigned long)loc_new & 0xf0000000;
+ target_addr >>= 2;
+
+ *loc_new = (*loc_new & ~0x03ffffff) | (target_addr & 0x03ffffff);
+
+ return 0;
+}
+
+
+static void __init apply_r_mips_hi16_rel(u32 *loc_orig, u32 *loc_new,
+ long offset)
+{
+ unsigned long insn = *loc_orig;
+ unsigned long target = (insn & 0xffff) << 16; /* high 16bits of target */
+
+ target += offset;
+
+ *loc_new = (insn & ~0xffff) | ((target >> 16) & 0xffff);
+}
+
+static int __init reloc_handler(u32 type, u32 *loc_orig, u32 *loc_new,
+ long offset)
+{
+ switch (type) {
+ case R_MIPS_64:
+ apply_r_mips_64_rel(loc_new, offset);
+ break;
+ case R_MIPS_32:
+ apply_r_mips_32_rel(loc_new, offset);
+ break;
+ case R_MIPS_26:
+ return apply_r_mips_26_rel(loc_orig, loc_new, offset);
+ case R_MIPS_HI16:
+ apply_r_mips_hi16_rel(loc_orig, loc_new, offset);
+ break;
+ default:
+ pr_err("Unhandled relocation type %d at 0x%pK\n", type,
+ loc_orig);
+ return -ENOEXEC;
+ }
+
+ return 0;
+}
+
+static int __init do_relocations(void *kbase_old, void *kbase_new, long offset)
+{
+ u32 *r;
+ u32 *loc_orig;
+ u32 *loc_new;
+ int type;
+ int res;
+
+ for (r = _relocation_start; r < _relocation_end; r++) {
+ /* Sentinel for last relocation */
+ if (*r == 0)
+ break;
+
+ type = (*r >> 24) & 0xff;
+ loc_orig = kbase_old + ((*r & 0x00ffffff) << 2);
+ loc_new = RELOCATED(loc_orig);
+
+ res = reloc_handler(type, loc_orig, loc_new, offset);
+ if (res)
+ return res;
+ }
+
+ return 0;
+}
+
+/*
+ * The exception table is filled in by the relocs tool after vmlinux is linked.
+ * It must be relocated separately since there will not be any relocation
+ * information for it filled in by the linker.
+ */
+static int __init relocate_exception_table(long offset)
+{
+ unsigned long *etable_start, *etable_end, *e;
+
+ etable_start = RELOCATED(&__start___ex_table);
+ etable_end = RELOCATED(&__stop___ex_table);
+
+ for (e = etable_start; e < etable_end; e++)
+ *e += offset;
+
+ return 0;
+}
+
+#ifdef CONFIG_RANDOMIZE_BASE
+
+static inline __init unsigned long rotate_xor(unsigned long hash,
+ const void *area, size_t size)
+{
+ const typeof(hash) *ptr = PTR_ALIGN(area, sizeof(hash));
+ size_t diff, i;
+
+ diff = (void *)ptr - area;
+ if (unlikely(size < diff + sizeof(hash)))
+ return hash;
+
+ size = ALIGN_DOWN(size - diff, sizeof(hash));
+
+ for (i = 0; i < size / sizeof(hash); i++) {
+ /* Rotate by odd number of bits and XOR. */
+ hash = (hash << ((sizeof(hash) * 8) - 7)) | (hash >> 7);
+ hash ^= ptr[i];
+ }
+
+ return hash;
+}
+
+static inline __init unsigned long get_random_boot(void)
+{
+ unsigned long entropy = random_get_entropy();
+ unsigned long hash = 0;
+
+ /* Attempt to create a simple but unpredictable starting entropy. */
+ hash = rotate_xor(hash, linux_banner, strlen(linux_banner));
+
+ /* Add in any runtime entropy we can get */
+ hash = rotate_xor(hash, &entropy, sizeof(entropy));
+
+#if defined(CONFIG_USE_OF)
+ /* Get any additional entropy passed in device tree */
+ if (initial_boot_params) {
+ int node, len;
+ u64 *prop;
+
+ node = fdt_path_offset(initial_boot_params, "/chosen");
+ if (node >= 0) {
+ prop = fdt_getprop_w(initial_boot_params, node,
+ "kaslr-seed", &len);
+ if (prop && (len == sizeof(u64)))
+ hash = rotate_xor(hash, prop, sizeof(*prop));
+ }
+ }
+#endif /* CONFIG_USE_OF */
+
+ return hash;
+}
+
+static inline __init bool kaslr_disabled(void)
+{
+ char *str;
+
+#if defined(CONFIG_CMDLINE_BOOL)
+ const char *builtin_cmdline = CONFIG_CMDLINE;
+
+ str = strstr(builtin_cmdline, "nokaslr");
+ if (str == builtin_cmdline ||
+ (str > builtin_cmdline && *(str - 1) == ' '))
+ return true;
+#endif
+ str = strstr(arcs_cmdline, "nokaslr");
+ if (str == arcs_cmdline || (str > arcs_cmdline && *(str - 1) == ' '))
+ return true;
+
+ return false;
+}
+
+static inline void __init *determine_relocation_address(void)
+{
+ /* Choose a new address for the kernel */
+ unsigned long kernel_length;
+ void *dest = &_text;
+ unsigned long offset;
+
+ if (kaslr_disabled())
+ return dest;
+
+ kernel_length = (long)_end - (long)(&_text);
+
+ offset = get_random_boot() << 16;
+ offset &= (CONFIG_RANDOMIZE_BASE_MAX_OFFSET - 1);
+ if (offset < kernel_length)
+ offset += ALIGN(kernel_length, 0xffff);
+
+ return RELOCATED(dest);
+}
+
+#else
+
+static inline void __init *determine_relocation_address(void)
+{
+ /*
+ * Choose a new address for the kernel
+ * For now we'll hard code the destination
+ */
+ return (void *)0xffffffff81000000;
+}
+
+#endif
+
+static inline int __init relocation_addr_valid(void *loc_new)
+{
+ if ((unsigned long)loc_new & 0x0000ffff) {
+ /* Inappropriately aligned new location */
+ return 0;
+ }
+ if ((unsigned long)loc_new < (unsigned long)&_end) {
+ /* New location overlaps original kernel */
+ return 0;
+ }
+ return 1;
+}
+
+static inline void __init update_kaslr_offset(unsigned long *addr, long offset)
+{
+ unsigned long *new_addr = (unsigned long *)RELOCATED(addr);
+
+ *new_addr = (unsigned long)offset;
+}
+
+#if defined(CONFIG_USE_OF)
+void __weak *plat_get_fdt(void)
+{
+ return NULL;
+}
+#endif
+
+void *__init relocate_kernel(void)
+{
+ void *loc_new;
+ unsigned long kernel_length;
+ unsigned long bss_length;
+ long offset = 0;
+ int res = 1;
+ /* Default to original kernel entry point */
+ void *kernel_entry = start_kernel;
+ void *fdt = NULL;
+
+ /* Get the command line */
+ fw_init_cmdline();
+#if defined(CONFIG_USE_OF)
+ /* Deal with the device tree */
+ fdt = plat_get_fdt();
+ early_init_dt_scan(fdt);
+ if (boot_command_line[0]) {
+ /* Boot command line was passed in device tree */
+ strscpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE);
+ }
+#endif /* CONFIG_USE_OF */
+
+ kernel_length = (long)(&_relocation_start) - (long)(&_text);
+ bss_length = (long)&__bss_stop - (long)&__bss_start;
+
+ loc_new = determine_relocation_address();
+
+ /* Sanity check relocation address */
+ if (relocation_addr_valid(loc_new))
+ offset = (unsigned long)loc_new - (unsigned long)(&_text);
+
+ /* Reset the command line now so we don't end up with a duplicate */
+ arcs_cmdline[0] = '\0';
+
+ if (offset) {
+ void (*fdt_relocated_)(void *) = NULL;
+#if defined(CONFIG_USE_OF)
+ unsigned long fdt_phys = virt_to_phys(fdt);
+
+ /*
+ * If built-in dtb is used then it will have been relocated
+ * during kernel _text relocation. If appended DTB is used
+ * then it will not be relocated, but it should remain
+ * intact in the original location. If dtb is loaded by
+ * the bootloader then it may need to be moved if it crosses
+ * the target memory area
+ */
+
+ if (fdt_phys >= virt_to_phys(RELOCATED(&_text)) &&
+ fdt_phys <= virt_to_phys(RELOCATED(&_end))) {
+ void *fdt_relocated =
+ RELOCATED(ALIGN((long)&_end, PAGE_SIZE));
+ memcpy(fdt_relocated, fdt, fdt_totalsize(fdt));
+ fdt = fdt_relocated;
+ fdt_relocated_ = RELOCATED(&plat_fdt_relocated);
+ }
+#endif /* CONFIG_USE_OF */
+
+ /* Copy the kernel to it's new location */
+ memcpy(loc_new, &_text, kernel_length);
+
+ /* Perform relocations on the new kernel */
+ res = do_relocations(&_text, loc_new, offset);
+ if (res < 0)
+ goto out;
+
+ /* Sync the caches ready for execution of new kernel */
+ sync_icache(loc_new, kernel_length);
+
+ res = relocate_exception_table(offset);
+ if (res < 0)
+ goto out;
+
+ /*
+ * The original .bss has already been cleared, and
+ * some variables such as command line parameters
+ * stored to it so make a copy in the new location.
+ */
+ memcpy(RELOCATED(&__bss_start), &__bss_start, bss_length);
+
+ /*
+ * If fdt was stored outside of the kernel image and
+ * had to be moved then update platform's state data
+ * with the new fdt location
+ */
+ if (fdt_relocated_)
+ fdt_relocated_(fdt);
+
+ /*
+ * Last chance for the platform to abort relocation.
+ * This may also be used by the platform to perform any
+ * initialisation required now that the new kernel is
+ * resident in memory and ready to be executed.
+ */
+ if (plat_post_relocation(offset))
+ goto out;
+
+ /* The current thread is now within the relocated image */
+ __current_thread_info = RELOCATED(&init_thread_union);
+
+ /* Return the new kernel's entry point */
+ kernel_entry = RELOCATED(start_kernel);
+
+ /* Error may occur before, so keep it at last */
+ update_kaslr_offset(&__kaslr_offset, offset);
+ }
+out:
+ return kernel_entry;
+}
+
+/*
+ * Show relocation information on panic.
+ */
+static void show_kernel_relocation(const char *level)
+{
+ if (__kaslr_offset > 0) {
+ printk(level);
+ pr_cont("Kernel relocated by 0x%pK\n", (void *)__kaslr_offset);
+ pr_cont(" .text @ 0x%pK\n", _text);
+ pr_cont(" .data @ 0x%pK\n", _sdata);
+ pr_cont(" .bss @ 0x%pK\n", __bss_start);
+ }
+}
+
+static int kernel_location_notifier_fn(struct notifier_block *self,
+ unsigned long v, void *p)
+{
+ show_kernel_relocation(KERN_EMERG);
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block kernel_location_notifier = {
+ .notifier_call = kernel_location_notifier_fn
+};
+
+static int __init register_kernel_offset_dumper(void)
+{
+ atomic_notifier_chain_register(&panic_notifier_list,
+ &kernel_location_notifier);
+ return 0;
+}
+__initcall(register_kernel_offset_dumper);