8a5d8473dd
Remove the s390 architecture implementation of probe_kernel_write() and instead use a new function s390_kernel_write() to modify kernel text and data everywhere. The s390 implementation of probe_kernel_write() was potentially broken since it modified memory in a read-modify-write fashion, which read four bytes, modified the requested bytes within those four bytes and wrote the result back. If two cpus would modify the same four byte area at different locations within that area, this could lead to corruption. Right now the only places which called probe_kernel_write() did run within stop_machine_run. Therefore the scenario can't happen right now, however that might change at any time. To fix this rename probe_kernel_write() to s390_kernel_write() which can have special semantics, like only call it while running within stop_machine(). Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
/*
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* Jump label s390 support
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*
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* Copyright IBM Corp. 2011
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* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
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*/
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <linux/stop_machine.h>
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#include <linux/jump_label.h>
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#include <asm/ipl.h>
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#ifdef HAVE_JUMP_LABEL
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struct insn {
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u16 opcode;
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s32 offset;
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} __packed;
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struct insn_args {
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struct jump_entry *entry;
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enum jump_label_type type;
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};
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static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn)
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{
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/* brcl 0,0 */
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insn->opcode = 0xc004;
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insn->offset = 0;
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}
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static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
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{
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/* brcl 15,offset */
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insn->opcode = 0xc0f4;
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insn->offset = (entry->target - entry->code) >> 1;
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}
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static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
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struct insn *new)
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{
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unsigned char *ipc = (unsigned char *)entry->code;
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unsigned char *ipe = (unsigned char *)expected;
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unsigned char *ipn = (unsigned char *)new;
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pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc);
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pr_emerg("Found: %02x %02x %02x %02x %02x %02x\n",
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ipc[0], ipc[1], ipc[2], ipc[3], ipc[4], ipc[5]);
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pr_emerg("Expected: %02x %02x %02x %02x %02x %02x\n",
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ipe[0], ipe[1], ipe[2], ipe[3], ipe[4], ipe[5]);
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pr_emerg("New: %02x %02x %02x %02x %02x %02x\n",
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ipn[0], ipn[1], ipn[2], ipn[3], ipn[4], ipn[5]);
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panic("Corrupted kernel text");
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}
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static struct insn orignop = {
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.opcode = 0xc004,
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.offset = JUMP_LABEL_NOP_OFFSET >> 1,
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};
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static void __jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type,
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int init)
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{
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struct insn old, new;
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if (type == JUMP_LABEL_ENABLE) {
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jump_label_make_nop(entry, &old);
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jump_label_make_branch(entry, &new);
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} else {
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jump_label_make_branch(entry, &old);
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jump_label_make_nop(entry, &new);
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}
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if (init) {
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if (memcmp((void *)entry->code, &orignop, sizeof(orignop)))
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jump_label_bug(entry, &orignop, &new);
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} else {
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if (memcmp((void *)entry->code, &old, sizeof(old)))
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jump_label_bug(entry, &old, &new);
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}
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s390_kernel_write((void *)entry->code, &new, sizeof(new));
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}
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static int __sm_arch_jump_label_transform(void *data)
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{
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struct insn_args *args = data;
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__jump_label_transform(args->entry, args->type, 0);
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return 0;
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}
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void arch_jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type)
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{
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struct insn_args args;
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args.entry = entry;
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args.type = type;
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stop_machine(__sm_arch_jump_label_transform, &args, NULL);
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}
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void arch_jump_label_transform_static(struct jump_entry *entry,
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enum jump_label_type type)
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{
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__jump_label_transform(entry, type, 1);
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}
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#endif
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