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Implement the architecture backend for jump label support on s390. For a shared kernel booted from a NSS silently disable jump labels because the NSS is read-only. Therefore jump labels will be disabled in a shared kernel and can't be activated. Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com> LKML-Reference: <6935d2c41ce111e1719176ed4bbd3dbe4de80855.1300299760.git.jbaron@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Jan Glauber
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Original file line number | Diff line number | Diff line change |
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#ifndef _ASM_S390_JUMP_LABEL_H | ||
#define _ASM_S390_JUMP_LABEL_H | ||
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#include <linux/types.h> | ||
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#define JUMP_LABEL_NOP_SIZE 6 | ||
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#ifdef CONFIG_64BIT | ||
#define ASM_PTR ".quad" | ||
#define ASM_ALIGN ".balign 8" | ||
#else | ||
#define ASM_PTR ".long" | ||
#define ASM_ALIGN ".balign 4" | ||
#endif | ||
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static __always_inline bool arch_static_branch(struct jump_label_key *key) | ||
{ | ||
asm goto("0: brcl 0,0\n" | ||
".pushsection __jump_table, \"aw\"\n" | ||
ASM_ALIGN "\n" | ||
ASM_PTR " 0b, %l[label], %0\n" | ||
".popsection\n" | ||
: : "X" (key) : : label); | ||
return false; | ||
label: | ||
return true; | ||
} | ||
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typedef unsigned long jump_label_t; | ||
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struct jump_entry { | ||
jump_label_t code; | ||
jump_label_t target; | ||
jump_label_t key; | ||
}; | ||
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#endif |
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/* | ||
* Jump label s390 support | ||
* | ||
* Copyright IBM Corp. 2011 | ||
* Author(s): Jan Glauber <jang@linux.vnet.ibm.com> | ||
*/ | ||
#include <linux/module.h> | ||
#include <linux/uaccess.h> | ||
#include <linux/stop_machine.h> | ||
#include <linux/jump_label.h> | ||
#include <asm/ipl.h> | ||
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#ifdef HAVE_JUMP_LABEL | ||
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struct insn { | ||
u16 opcode; | ||
s32 offset; | ||
} __packed; | ||
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struct insn_args { | ||
unsigned long *target; | ||
struct insn *insn; | ||
ssize_t size; | ||
}; | ||
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static int __arch_jump_label_transform(void *data) | ||
{ | ||
struct insn_args *args = data; | ||
int rc; | ||
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rc = probe_kernel_write(args->target, args->insn, args->size); | ||
WARN_ON_ONCE(rc < 0); | ||
return 0; | ||
} | ||
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void arch_jump_label_transform(struct jump_entry *entry, | ||
enum jump_label_type type) | ||
{ | ||
struct insn_args args; | ||
struct insn insn; | ||
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if (type == JUMP_LABEL_ENABLE) { | ||
/* brcl 15,offset */ | ||
insn.opcode = 0xc0f4; | ||
insn.offset = (entry->target - entry->code) >> 1; | ||
} else { | ||
/* brcl 0,0 */ | ||
insn.opcode = 0xc004; | ||
insn.offset = 0; | ||
} | ||
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args.target = (void *) entry->code; | ||
args.insn = &insn; | ||
args.size = JUMP_LABEL_NOP_SIZE; | ||
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stop_machine(__arch_jump_label_transform, &args, NULL); | ||
} | ||
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#endif |