diff options
Diffstat (limited to 'arch/i386/kernel/paravirt.c')
| -rw-r--r-- | arch/i386/kernel/paravirt.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c index 478192cd4b90..d46460426446 100644 --- a/arch/i386/kernel/paravirt.c +++ b/arch/i386/kernel/paravirt.c @@ -45,6 +45,49 @@ char *memory_setup(void) return paravirt_ops.memory_setup(); } +/* Simple instruction patching code. */ +#define DEF_NATIVE(name, code) \ + extern const char start_##name[], end_##name[]; \ + asm("start_" #name ": " code "; end_" #name ":") +DEF_NATIVE(cli, "cli"); +DEF_NATIVE(sti, "sti"); +DEF_NATIVE(popf, "push %eax; popf"); +DEF_NATIVE(pushf, "pushf; pop %eax"); +DEF_NATIVE(pushf_cli, "pushf; pop %eax; cli"); +DEF_NATIVE(iret, "iret"); +DEF_NATIVE(sti_sysexit, "sti; sysexit"); + +static const struct native_insns +{ + const char *start, *end; +} native_insns[] = { + [PARAVIRT_IRQ_DISABLE] = { start_cli, end_cli }, + [PARAVIRT_IRQ_ENABLE] = { start_sti, end_sti }, + [PARAVIRT_RESTORE_FLAGS] = { start_popf, end_popf }, + [PARAVIRT_SAVE_FLAGS] = { start_pushf, end_pushf }, + [PARAVIRT_SAVE_FLAGS_IRQ_DISABLE] = { start_pushf_cli, end_pushf_cli }, + [PARAVIRT_INTERRUPT_RETURN] = { start_iret, end_iret }, + [PARAVIRT_STI_SYSEXIT] = { start_sti_sysexit, end_sti_sysexit }, +}; + +static unsigned native_patch(u8 type, u16 clobbers, void *insns, unsigned len) +{ + unsigned int insn_len; + + /* Don't touch it if we don't have a replacement */ + if (type >= ARRAY_SIZE(native_insns) || !native_insns[type].start) + return len; + + insn_len = native_insns[type].end - native_insns[type].start; + + /* Similarly if we can't fit replacement. */ + if (len < insn_len) + return len; + + memcpy(insns, native_insns[type].start, insn_len); + return insn_len; +} + static fastcall unsigned long native_get_debugreg(int regno) { unsigned long val = 0; /* Damn you, gcc! */ @@ -349,6 +392,7 @@ struct paravirt_ops paravirt_ops = { .paravirt_enabled = 0, .kernel_rpl = 0, + .patch = native_patch, .banner = default_banner, .arch_setup = native_nop, .memory_setup = machine_specific_memory_setup, |