/*
   *  Copyright (C) 2001 Ben. Herrenschmidt (benh@kernel.crashing.org)
   *
   *  Modifications for ppc64:
   *      Copyright (C) 2003 Dave Engebretsen <engebret@us.ibm.com>
   *
   *  Copyright 2008 Michael Ellerman, IBM Corporation.
   *
   *  This program is free software; you can redistribute it and/or
   *  modify it under the terms of the GNU General Public License
   *  as published by the Free Software Foundation; either version
   *  2 of the License, or (at your option) any later version.
   */
  
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/string.h>
  #include <linux/init.h>
  #include <asm/cputable.h>
  #include <asm/code-patching.h>
  #include <asm/page.h>
  #include <asm/sections.h>
  
  
  struct fixup_entry {
  	unsigned long	mask;
  	unsigned long	value;
  	long		start_off;
  	long		end_off;
  	long		alt_start_off;
  	long		alt_end_off;
  };
  
  static unsigned int *calc_addr(struct fixup_entry *fcur, long offset)
  {
  	/*
  	 * We store the offset to the code as a negative offset from
  	 * the start of the alt_entry, to support the VDSO. This
  	 * routine converts that back into an actual address.
  	 */
  	return (unsigned int *)((unsigned long)fcur + offset);
  }
  
  static int patch_alt_instruction(unsigned int *src, unsigned int *dest,
  				 unsigned int *alt_start, unsigned int *alt_end)
  {
  	unsigned int instr;
  
  	instr = *src;
  
  	if (instr_is_relative_branch(*src)) {
  		unsigned int *target = (unsigned int *)branch_target(src);
  
  		/* Branch within the section doesn't need translating */
  		if (target < alt_start || target >= alt_end) {
  			instr = translate_branch(dest, src);
  			if (!instr)
  				return 1;
  		}
  	}
  
  	patch_instruction(dest, instr);
  
  	return 0;
  }
  
  static int patch_feature_section(unsigned long value, struct fixup_entry *fcur)
  {
  	unsigned int *start, *end, *alt_start, *alt_end, *src, *dest;
  
  	start = calc_addr(fcur, fcur->start_off);
  	end = calc_addr(fcur, fcur->end_off);
  	alt_start = calc_addr(fcur, fcur->alt_start_off);
  	alt_end = calc_addr(fcur, fcur->alt_end_off);
  
  	if ((alt_end - alt_start) > (end - start))
  		return 1;
  
  	if ((value & fcur->mask) == fcur->value)
  		return 0;
  
  	src = alt_start;
  	dest = start;
  
  	for (; src < alt_end; src++, dest++) {
  		if (patch_alt_instruction(src, dest, alt_start, alt_end))
  			return 1;
  	}
  
  	for (; dest < end; dest++)
  		patch_instruction(dest, PPC_INST_NOP);
  
  	return 0;
  }
  
  void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
  {
  	struct fixup_entry *fcur, *fend;
  
  	fcur = fixup_start;
  	fend = fixup_end;
  
  	for (; fcur < fend; fcur++) {
  		if (patch_feature_section(value, fcur)) {
  			WARN_ON(1);
  			printk("Unable to patch feature section at %p - %p" \
  				" with %p - %p
  ",
  				calc_addr(fcur, fcur->start_off),
  				calc_addr(fcur, fcur->end_off),
  				calc_addr(fcur, fcur->alt_start_off),
  				calc_addr(fcur, fcur->alt_end_off));
  		}
  	}
  }
  
  void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
  {
  	long *start, *end;
  	unsigned int *dest;
  
  	if (!(value & CPU_FTR_LWSYNC))
  		return ;
  
  	start = fixup_start;
  	end = fixup_end;
  
  	for (; start < end; start++) {
  		dest = (void *)start + *start;
  		patch_instruction(dest, PPC_INST_LWSYNC);
  	}
  }
  
  void do_final_fixups(void)
  {
  #if defined(CONFIG_PPC64) && defined(CONFIG_RELOCATABLE)
  	int *src, *dest;
  	unsigned long length;
  
  	if (PHYSICAL_START == 0)
  		return;
  
  	src = (int *)(KERNELBASE + PHYSICAL_START);
  	dest = (int *)KERNELBASE;
  	length = (__end_interrupts - _stext) / sizeof(int);
  
  	while (length--) {
  		patch_instruction(dest, *src);
  		src++;
  		dest++;
  	}
  #endif
  }
  
  #ifdef CONFIG_FTR_FIXUP_SELFTEST
  
  #define check(x)	\
  	if (!(x)) printk("feature-fixups: test failed at line %d
  ", __LINE__);
  
  /* This must be after the text it fixes up, vmlinux.lds.S enforces that atm */
  static struct fixup_entry fixup;
  
  static long calc_offset(struct fixup_entry *entry, unsigned int *p)
  {
  	return (unsigned long)p - (unsigned long)entry;
  }
  
  void test_basic_patching(void)
  {
  	extern unsigned int ftr_fixup_test1;
  	extern unsigned int end_ftr_fixup_test1;
  	extern unsigned int ftr_fixup_test1_orig;
  	extern unsigned int ftr_fixup_test1_expected;
  	int size = &end_ftr_fixup_test1 - &ftr_fixup_test1;
  
  	fixup.value = fixup.mask = 8;
  	fixup.start_off = calc_offset(&fixup, &ftr_fixup_test1 + 1);
  	fixup.end_off = calc_offset(&fixup, &ftr_fixup_test1 + 2);
  	fixup.alt_start_off = fixup.alt_end_off = 0;
  
  	/* Sanity check */
  	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
  
  	/* Check we don't patch if the value matches */
  	patch_feature_section(8, &fixup);
  	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
  
  	/* Check we do patch if the value doesn't match */
  	patch_feature_section(0, &fixup);
  	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
  
  	/* Check we do patch if the mask doesn't match */
  	memcpy(&ftr_fixup_test1, &ftr_fixup_test1_orig, size);
  	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
  	patch_feature_section(~8, &fixup);
  	check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
  }
  
  static void test_alternative_patching(void)
  {
  	extern unsigned int ftr_fixup_test2;
  	extern unsigned int end_ftr_fixup_test2;
  	extern unsigned int ftr_fixup_test2_orig;
  	extern unsigned int ftr_fixup_test2_alt;
  	extern unsigned int ftr_fixup_test2_expected;
  	int size = &end_ftr_fixup_test2 - &ftr_fixup_test2;
  
  	fixup.value = fixup.mask = 0xF;
  	fixup.start_off = calc_offset(&fixup, &ftr_fixup_test2 + 1);
  	fixup.end_off = calc_offset(&fixup, &ftr_fixup_test2 + 2);
  	fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test2_alt);
  	fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test2_alt + 1);
  
  	/* Sanity check */
  	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
  
  	/* Check we don't patch if the value matches */
  	patch_feature_section(0xF, &fixup);
  	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
  
  	/* Check we do patch if the value doesn't match */
  	patch_feature_section(0, &fixup);
  	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
  
  	/* Check we do patch if the mask doesn't match */
  	memcpy(&ftr_fixup_test2, &ftr_fixup_test2_orig, size);
  	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
  	patch_feature_section(~0xF, &fixup);
  	check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
  }
  
  static void test_alternative_case_too_big(void)
  {
  	extern unsigned int ftr_fixup_test3;
  	extern unsigned int end_ftr_fixup_test3;
  	extern unsigned int ftr_fixup_test3_orig;
  	extern unsigned int ftr_fixup_test3_alt;
  	int size = &end_ftr_fixup_test3 - &ftr_fixup_test3;
  
  	fixup.value = fixup.mask = 0xC;
  	fixup.start_off = calc_offset(&fixup, &ftr_fixup_test3 + 1);
  	fixup.end_off = calc_offset(&fixup, &ftr_fixup_test3 + 2);
  	fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test3_alt);
  	fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test3_alt + 2);
  
  	/* Sanity check */
  	check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
  
  	/* Expect nothing to be patched, and the error returned to us */
  	check(patch_feature_section(0xF, &fixup) == 1);
  	check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
  	check(patch_feature_section(0, &fixup) == 1);
  	check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
  	check(patch_feature_section(~0xF, &fixup) == 1);
  	check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
  }
  
  static void test_alternative_case_too_small(void)
  {
  	extern unsigned int ftr_fixup_test4;
  	extern unsigned int end_ftr_fixup_test4;
  	extern unsigned int ftr_fixup_test4_orig;
  	extern unsigned int ftr_fixup_test4_alt;
  	extern unsigned int ftr_fixup_test4_expected;
  	int size = &end_ftr_fixup_test4 - &ftr_fixup_test4;
  	unsigned long flag;
  
  	/* Check a high-bit flag */
  	flag = 1UL << ((sizeof(unsigned long) - 1) * 8);
  	fixup.value = fixup.mask = flag;
  	fixup.start_off = calc_offset(&fixup, &ftr_fixup_test4 + 1);
  	fixup.end_off = calc_offset(&fixup, &ftr_fixup_test4 + 5);
  	fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test4_alt);
  	fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test4_alt + 2);
  
  	/* Sanity check */
  	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
  
  	/* Check we don't patch if the value matches */
  	patch_feature_section(flag, &fixup);
  	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
  
  	/* Check we do patch if the value doesn't match */
  	patch_feature_section(0, &fixup);
  	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
  
  	/* Check we do patch if the mask doesn't match */
  	memcpy(&ftr_fixup_test4, &ftr_fixup_test4_orig, size);
  	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
  	patch_feature_section(~flag, &fixup);
  	check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
  }
  
  static void test_alternative_case_with_branch(void)
  {
  	extern unsigned int ftr_fixup_test5;
  	extern unsigned int end_ftr_fixup_test5;
  	extern unsigned int ftr_fixup_test5_expected;
  	int size = &end_ftr_fixup_test5 - &ftr_fixup_test5;
  
  	check(memcmp(&ftr_fixup_test5, &ftr_fixup_test5_expected, size) == 0);
  }
  
  static void test_alternative_case_with_external_branch(void)
  {
  	extern unsigned int ftr_fixup_test6;
  	extern unsigned int end_ftr_fixup_test6;
  	extern unsigned int ftr_fixup_test6_expected;
  	int size = &end_ftr_fixup_test6 - &ftr_fixup_test6;
  
  	check(memcmp(&ftr_fixup_test6, &ftr_fixup_test6_expected, size) == 0);
  }
  
  static void test_cpu_macros(void)
  {
  	extern u8 ftr_fixup_test_FTR_macros;
  	extern u8 ftr_fixup_test_FTR_macros_expected;
  	unsigned long size = &ftr_fixup_test_FTR_macros_expected -
  			     &ftr_fixup_test_FTR_macros;
  
  	/* The fixups have already been done for us during boot */
  	check(memcmp(&ftr_fixup_test_FTR_macros,
  		     &ftr_fixup_test_FTR_macros_expected, size) == 0);
  }
  
  static void test_fw_macros(void)
  {
  #ifdef CONFIG_PPC64
  	extern u8 ftr_fixup_test_FW_FTR_macros;
  	extern u8 ftr_fixup_test_FW_FTR_macros_expected;
  	unsigned long size = &ftr_fixup_test_FW_FTR_macros_expected -
  			     &ftr_fixup_test_FW_FTR_macros;
  
  	/* The fixups have already been done for us during boot */
  	check(memcmp(&ftr_fixup_test_FW_FTR_macros,
  		     &ftr_fixup_test_FW_FTR_macros_expected, size) == 0);
  #endif
  }
  
  static void test_lwsync_macros(void)
  {
  	extern u8 lwsync_fixup_test;
  	extern u8 end_lwsync_fixup_test;
  	extern u8 lwsync_fixup_test_expected_LWSYNC;
  	extern u8 lwsync_fixup_test_expected_SYNC;
  	unsigned long size = &end_lwsync_fixup_test -
  			     &lwsync_fixup_test;
  
  	/* The fixups have already been done for us during boot */
  	if (cur_cpu_spec->cpu_features & CPU_FTR_LWSYNC) {
  		check(memcmp(&lwsync_fixup_test,
  			     &lwsync_fixup_test_expected_LWSYNC, size) == 0);
  	} else {
  		check(memcmp(&lwsync_fixup_test,
  			     &lwsync_fixup_test_expected_SYNC, size) == 0);
  	}
  }
  
  static int __init test_feature_fixups(void)
  {
  	printk(KERN_DEBUG "Running feature fixup self-tests ...
  ");
  
  	test_basic_patching();
  	test_alternative_patching();
  	test_alternative_case_too_big();
  	test_alternative_case_too_small();
  	test_alternative_case_with_branch();
  	test_alternative_case_with_external_branch();
  	test_cpu_macros();
  	test_fw_macros();
  	test_lwsync_macros();
  
  	return 0;
  }
  late_initcall(test_feature_fixups);
  
  #endif /* CONFIG_FTR_FIXUP_SELFTEST */