Revert "s390: introduce CPU alternatives"

BugLink: http://bugs.launchpad.net/bugs/1768474

This reverts commit 008e2cfd to be
replaced by the upstream patch set from 4.4.130.
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/s390/include/asm/alternative.h

-#ifndef _ASM_S390_ALTERNATIVE_H
-#define _ASM_S390_ALTERNATIVE_H
-
-#ifndef __ASSEMBLY__
-
-#include <linux/types.h>
-#include <linux/stddef.h>
-#include <linux/stringify.h>
-
-struct alt_instr {
-	s32 instr_offset;	/* original instruction */
-	s32 repl_offset;	/* offset to replacement instruction */
-	u16 facility;		/* facility bit set for replacement */
-	u8  instrlen;		/* length of original instruction */
-	u8  replacementlen;	/* length of new instruction */
-} __packed;
-
-extern void apply_alternative_instructions(void);
-extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
-
-/*
- * |661:       |662:      |6620      |663:
- * +-----------+---------------------+
- * | oldinstr  | oldinstr_padding    |
- * |           +----------+----------+
- * |           |          |          |
- * |           | >6 bytes |6/4/2 nops|
- * |           |6 bytes jg----------->
- * +-----------+---------------------+
- *               ^^ static padding ^^
- *
- * .altinstr_replacement section
- * +---------------------+-----------+
- * |6641:                            |6651:
- * | alternative instr 1             |
- * +-----------+---------+- - - - - -+
- * |6642:                |6652:      |
- * | alternative instr 2 | padding
- * +---------------------+- - - - - -+
- *                        ^ runtime ^
- *
- * .altinstructions section
- * +---------------------------------+
- * | alt_instr entries for each      |
- * | alternative instr               |
- * +---------------------------------+
- */
-
-#define b_altinstr(num)	"664"#num
-#define e_altinstr(num)	"665"#num
-
-#define e_oldinstr_pad_end	"663"
-#define oldinstr_len		"662b-661b"
-#define oldinstr_total_len	e_oldinstr_pad_end"b-661b"
-#define altinstr_len(num)	e_altinstr(num)"b-"b_altinstr(num)"b"
-#define oldinstr_pad_len(num) \
-	"-(((" altinstr_len(num) ")-(" oldinstr_len ")) > 0) * " \
-	"((" altinstr_len(num) ")-(" oldinstr_len "))"
-
-#define INSTR_LEN_SANITY_CHECK(len)					\
-	".if " len " > 254\n"						\
-	"\t.error \"cpu alternatives does not support instructions "	\
-		"blocks > 254 bytes\"\n"				\
-	".endif\n"							\
-	".if (" len ") %% 2\n"						\
-	"\t.error \"cpu alternatives instructions length is odd\"\n"	\
-	".endif\n"
-
-#define OLDINSTR_PADDING(oldinstr, num)					\
-	".if " oldinstr_pad_len(num) " > 6\n"				\
-	"\tjg " e_oldinstr_pad_end "f\n"				\
-	"6620:\n"							\
-	"\t.fill (" oldinstr_pad_len(num) " - (6620b-662b)) / 2, 2, 0x0700\n" \
-	".else\n"							\
-	"\t.fill " oldinstr_pad_len(num) " / 6, 6, 0xc0040000\n"	\
-	"\t.fill " oldinstr_pad_len(num) " %% 6 / 4, 4, 0x47000000\n"	\
-	"\t.fill " oldinstr_pad_len(num) " %% 6 %% 4 / 2, 2, 0x0700\n"	\
-	".endif\n"
-
-#define OLDINSTR(oldinstr, num)						\
-	"661:\n\t" oldinstr "\n662:\n"					\
-	OLDINSTR_PADDING(oldinstr, num)					\
-	e_oldinstr_pad_end ":\n"					\
-	INSTR_LEN_SANITY_CHECK(oldinstr_len)
-
-#define OLDINSTR_2(oldinstr, num1, num2)				\
-	"661:\n\t" oldinstr "\n662:\n"					\
-	".if " altinstr_len(num1) " < " altinstr_len(num2) "\n"		\
-	OLDINSTR_PADDING(oldinstr, num2)				\
-	".else\n"							\
-	OLDINSTR_PADDING(oldinstr, num1)				\
-	".endif\n"							\
-	e_oldinstr_pad_end ":\n"					\
-	INSTR_LEN_SANITY_CHECK(oldinstr_len)
-
-#define ALTINSTR_ENTRY(facility, num)					\
-	"\t.long 661b - .\n"			/* old instruction */	\
-	"\t.long " b_altinstr(num)"b - .\n"	/* alt instruction */	\
-	"\t.word " __stringify(facility) "\n"	/* facility bit    */	\
-	"\t.byte " oldinstr_total_len "\n"	/* source len      */	\
-	"\t.byte " altinstr_len(num) "\n"	/* alt instruction len */
-
-#define ALTINSTR_REPLACEMENT(altinstr, num)	/* replacement */	\
-	b_altinstr(num)":\n\t" altinstr "\n" e_altinstr(num) ":\n"	\
-	INSTR_LEN_SANITY_CHECK(altinstr_len(num))
-
-/* alternative assembly primitive: */
-#define ALTERNATIVE(oldinstr, altinstr, facility) \
-	".pushsection .altinstr_replacement, \"ax\"\n"			\
-	ALTINSTR_REPLACEMENT(altinstr, 1)				\
-	".popsection\n"							\
-	OLDINSTR(oldinstr, 1)						\
-	".pushsection .altinstructions,\"a\"\n"				\
-	ALTINSTR_ENTRY(facility, 1)					\
-	".popsection\n"
-
-#define ALTERNATIVE_2(oldinstr, altinstr1, facility1, altinstr2, facility2)\
-	".pushsection .altinstr_replacement, \"ax\"\n"			\
-	ALTINSTR_REPLACEMENT(altinstr1, 1)				\
-	ALTINSTR_REPLACEMENT(altinstr2, 2)				\
-	".popsection\n"							\
-	OLDINSTR_2(oldinstr, 1, 2)					\
-	".pushsection .altinstructions,\"a\"\n"				\
-	ALTINSTR_ENTRY(facility1, 1)					\
-	ALTINSTR_ENTRY(facility2, 2)					\
-	".popsection\n"
-
-/*
- * Alternative instructions for different CPU types or capabilities.
- *
- * This allows to use optimized instructions even on generic binary
- * kernels.
- *
- * oldinstr is padded with jump and nops at compile time if altinstr is
- * longer. altinstr is padded with jump and nops at run-time during patching.
- *
- * For non barrier like inlines please define new variants
- * without volatile and memory clobber.
- */
-#define alternative(oldinstr, altinstr, facility)			\
-	asm volatile(ALTERNATIVE(oldinstr, altinstr, facility) : : : "memory")
-
-#define alternative_2(oldinstr, altinstr1, facility1, altinstr2, facility2) \
-	asm volatile(ALTERNATIVE_2(oldinstr, altinstr1, facility1,	    \
-				   altinstr2, facility2) ::: "memory")
-
-#endif /* __ASSEMBLY__ */
-
-#endif /* _ASM_S390_ALTERNATIVE_H */

arch/s390/kernel/Makefile

@@ -44,7 +44,7 @@ obj-y	+= processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o
 obj-y	+= debug.o irq.o ipl.o dis.o diag.o sclp.o vdso.o
 obj-y	+= sysinfo.o jump_label.o lgr.o os_info.o machine_kexec.o pgm_check.o
 obj-y	+= runtime_instr.o cache.o dumpstack.o
-obj-y	+= entry.o reipl.o relocate_kernel.o alternative.o
+obj-y	+= entry.o reipl.o relocate_kernel.o
 
 extra-y				+= head.o head64.o vmlinux.lds
 

arch/s390/kernel/alternative.c

-#include <linux/module.h>
-#include <asm/alternative.h>
-#include <asm/facility.h>
-
-#define MAX_PATCH_LEN (255 - 1)
-
-static int __initdata_or_module alt_instr_disabled;
-
-static int __init disable_alternative_instructions(char *str)
-{
-	alt_instr_disabled = 1;
-	return 0;
-}
-
-early_param("noaltinstr", disable_alternative_instructions);
-
-struct brcl_insn {
-	u16 opc;
-	s32 disp;
-} __packed;
-
-static u16 __initdata_or_module nop16 = 0x0700;
-static u32 __initdata_or_module nop32 = 0x47000000;
-static struct brcl_insn __initdata_or_module nop48 = {
-	0xc004, 0
-};
-
-static const void * __initdata_or_module nops[] = {
-	&nop16,
-	&nop32,
-	&nop48
-};
-
-static void __init_or_module add_jump_padding(void *insns, unsigned int len)
-{
-	struct brcl_insn brcl = {
-		0xc0f4,
-		len / 2
-	};
-
-	memcpy(insns, &brcl, sizeof(brcl));
-	insns += sizeof(brcl);
-	len -= sizeof(brcl);
-
-	while (len > 0) {
-		memcpy(insns, &nop16, 2);
-		insns += 2;
-		len -= 2;
-	}
-}
-
-static void __init_or_module add_padding(void *insns, unsigned int len)
-{
-	if (len > 6)
-		add_jump_padding(insns, len);
-	else if (len >= 2)
-		memcpy(insns, nops[len / 2 - 1], len);
-}
-
-static void __init_or_module __apply_alternatives(struct alt_instr *start,
-						  struct alt_instr *end)
-{
-	struct alt_instr *a;
-	u8 *instr, *replacement;
-	u8 insnbuf[MAX_PATCH_LEN];
-
-	/*
-	 * The scan order should be from start to end. A later scanned
-	 * alternative code can overwrite previously scanned alternative code.
-	 */
-	for (a = start; a < end; a++) {
-		int insnbuf_sz = 0;
-
-		instr = (u8 *)&a->instr_offset + a->instr_offset;
-		replacement = (u8 *)&a->repl_offset + a->repl_offset;
-
-		if (!test_facility(a->facility))
-			continue;
-
-		if (unlikely(a->instrlen % 2 || a->replacementlen % 2)) {
-			WARN_ONCE(1, "cpu alternatives instructions length is "
-				     "odd, skipping patching\n");
-			continue;
-		}
-
-		memcpy(insnbuf, replacement, a->replacementlen);
-		insnbuf_sz = a->replacementlen;
-
-		if (a->instrlen > a->replacementlen) {
-			add_padding(insnbuf + a->replacementlen,
-				    a->instrlen - a->replacementlen);
-			insnbuf_sz += a->instrlen - a->replacementlen;
-		}
-
-		s390_kernel_write(instr, insnbuf, insnbuf_sz);
-	}
-}
-
-void __init_or_module apply_alternatives(struct alt_instr *start,
-					 struct alt_instr *end)
-{
-	if (!alt_instr_disabled)
-		__apply_alternatives(start, end);
-}
-
-extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
-void __init apply_alternative_instructions(void)
-{
-	apply_alternatives(__alt_instructions, __alt_instructions_end);
-}

arch/s390/kernel/module.c

@@ -31,7 +31,6 @@
 #include <linux/kernel.h>
 #include <linux/moduleloader.h>
 #include <linux/bug.h>
-#include <asm/alternative.h>
 
 #if 0
 #define DEBUGP printk
@@ -425,18 +424,6 @@ int module_finalize(const Elf_Ehdr *hdr,
 		    const Elf_Shdr *sechdrs,
 		    struct module *me)
 {
-	const Elf_Shdr *s;
-	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
-
-	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
-		if (!strcmp(".altinstructions", secstrings + s->sh_name)) {
-			/* patch .altinstructions */
-			void *aseg = (void *)s->sh_addr;
-
-			apply_alternatives(aseg, aseg + s->sh_size);
-		}
-	}
-
 	jump_label_apply_nops(me);
 	vfree(me->arch.syminfo);
 	me->arch.syminfo = NULL;

arch/s390/kernel/setup.c

@@ -63,7 +63,6 @@
 #include <asm/sclp.h>
 #include <asm/sysinfo.h>
 #include <asm/numa.h>
-#include <asm/alternative.h>
 #include "entry.h"
 
 /*
@@ -894,8 +893,6 @@ void __init setup_arch(char **cmdline_p)
 	conmode_default();
 	set_preferred_console();
 
-	apply_alternative_instructions();
-
 	/* Setup zfcpdump support */
 	setup_zfcpdump();
 

arch/s390/kernel/vmlinux.lds.S

@@ -78,29 +78,6 @@ SECTIONS
 		EXIT_DATA
 	}
 
-	/*
-	 * struct alt_inst entries. From the header (alternative.h):
-	 * "Alternative instructions for different CPU types or capabilities"
-	 * Think locking instructions on spinlocks.
-	 * Note, that it is a part of __init region.
-	 */
-	. = ALIGN(8);
-	.altinstructions : {
-		__alt_instructions = .;
-		*(.altinstructions)
-		__alt_instructions_end = .;
-	}
-
-	/*
-	 * And here are the replacement instructions. The linker sticks
-	 * them as binary blobs. The .altinstructions has enough data to
-	 * get the address and the length of them to patch the kernel safely.
-	 * Note, that it is a part of __init region.
-	 */
-	.altinstr_replacement : {
-		*(.altinstr_replacement)
-	}
-
 	/* early.c uses stsi, which requires page aligned data. */
 	. = ALIGN(PAGE_SIZE);
 	INIT_DATA_SECTION(0x100)