diff options
Diffstat (limited to '')
-rw-r--r-- | arch/s390/kernel/jump_label.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c new file mode 100644 index 000000000..9156653b5 --- /dev/null +++ b/arch/s390/kernel/jump_label.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Jump label s390 support + * + * Copyright IBM Corp. 2011 + * Author(s): Jan Glauber <jang@linux.vnet.ibm.com> + */ +#include <linux/uaccess.h> +#include <linux/stop_machine.h> +#include <linux/jump_label.h> +#include <asm/ipl.h> + +struct insn { + u16 opcode; + s32 offset; +} __packed; + +static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn) +{ + /* brcl 0,offset */ + insn->opcode = 0xc004; + insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1; +} + +static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn) +{ + /* brcl 15,offset */ + insn->opcode = 0xc0f4; + insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1; +} + +static void jump_label_bug(struct jump_entry *entry, struct insn *expected, + struct insn *new) +{ + unsigned char *ipc = (unsigned char *)jump_entry_code(entry); + unsigned char *ipe = (unsigned char *)expected; + unsigned char *ipn = (unsigned char *)new; + + pr_emerg("Jump label code mismatch at %pS [%px]\n", ipc, ipc); + pr_emerg("Found: %6ph\n", ipc); + pr_emerg("Expected: %6ph\n", ipe); + pr_emerg("New: %6ph\n", ipn); + panic("Corrupted kernel text"); +} + +static struct insn orignop = { + .opcode = 0xc004, + .offset = JUMP_LABEL_NOP_OFFSET >> 1, +}; + +static void __jump_label_transform(struct jump_entry *entry, + enum jump_label_type type, + int init) +{ + void *code = (void *)jump_entry_code(entry); + struct insn old, new; + + if (type == JUMP_LABEL_JMP) { + jump_label_make_nop(entry, &old); + jump_label_make_branch(entry, &new); + } else { + jump_label_make_branch(entry, &old); + jump_label_make_nop(entry, &new); + } + if (init) { + if (memcmp(code, &orignop, sizeof(orignop))) + jump_label_bug(entry, &orignop, &new); + } else { + if (memcmp(code, &old, sizeof(old))) + jump_label_bug(entry, &old, &new); + } + s390_kernel_write(code, &new, sizeof(new)); +} + +static void __jump_label_sync(void *dummy) +{ +} + +void arch_jump_label_transform(struct jump_entry *entry, + enum jump_label_type type) +{ + __jump_label_transform(entry, type, 0); + smp_call_function(__jump_label_sync, NULL, 1); +} + +void arch_jump_label_transform_static(struct jump_entry *entry, + enum jump_label_type type) +{ + __jump_label_transform(entry, type, 1); +} |