diff options
| -rw-r--r-- | arch/x86/kernel/umip.c | 62 |
1 files changed, 58 insertions, 4 deletions
diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c index 1f1f2d54dab5..dabbac30acdf 100644 --- a/arch/x86/kernel/umip.c +++ b/arch/x86/kernel/umip.c @@ -82,6 +82,57 @@ #define UMIP_INST_SLDT 3 /* 0F 00 /0 */ #define UMIP_INST_STR 4 /* 0F 00 /1 */ +const char * const umip_insns[5] = { + [UMIP_INST_SGDT] = "SGDT", + [UMIP_INST_SIDT] = "SIDT", + [UMIP_INST_SMSW] = "SMSW", + [UMIP_INST_SLDT] = "SLDT", + [UMIP_INST_STR] = "STR", +}; + +#define umip_pr_err(regs, fmt, ...) \ + umip_printk(regs, KERN_ERR, fmt, ##__VA_ARGS__) +#define umip_pr_warning(regs, fmt, ...) \ + umip_printk(regs, KERN_WARNING, fmt, ##__VA_ARGS__) + +/** + * umip_printk() - Print a rate-limited message + * @regs: Register set with the context in which the warning is printed + * @log_level: Kernel log level to print the message + * @fmt: The text string to print + * + * Print the text contained in @fmt. The print rate is limited to bursts of 5 + * messages every two minutes. The purpose of this customized version of + * printk() is to print messages when user space processes use any of the + * UMIP-protected instructions. Thus, the printed text is prepended with the + * task name and process ID number of the current task as well as the + * instruction and stack pointers in @regs as seen when entering kernel mode. + * + * Returns: + * + * None. + */ +static __printf(3, 4) +void umip_printk(const struct pt_regs *regs, const char *log_level, + const char *fmt, ...) +{ + /* Bursts of 5 messages every two minutes */ + static DEFINE_RATELIMIT_STATE(ratelimit, 2 * 60 * HZ, 5); + struct task_struct *tsk = current; + struct va_format vaf; + va_list args; + + if (!__ratelimit(&ratelimit)) + return; + + va_start(args, fmt); + vaf.fmt = fmt; + vaf.va = &args; + printk("%s" pr_fmt("%s[%d] ip:%lx sp:%lx: %pV"), log_level, tsk->comm, + task_pid_nr(tsk), regs->ip, regs->sp, &vaf); + va_end(args); +} + /** * identify_insn() - Identify a UMIP-protected instruction * @insn: Instruction structure with opcode and ModRM byte. @@ -236,10 +287,8 @@ static void force_sig_info_umip_fault(void __user *addr, struct pt_regs *regs) if (!(show_unhandled_signals && unhandled_signal(tsk, SIGSEGV))) return; - pr_err_ratelimited("%s[%d] umip emulation segfault ip:%lx sp:%lx error:%x in %lx\n", - tsk->comm, task_pid_nr(tsk), regs->ip, - regs->sp, X86_PF_USER | X86_PF_WRITE, - regs->ip); + umip_pr_err(regs, "segfault in emulation. error%x\n", + X86_PF_USER | X86_PF_WRITE); } /** @@ -326,10 +375,15 @@ bool fixup_umip_exception(struct pt_regs *regs) if (umip_inst < 0) return false; + umip_pr_warning(regs, "%s instruction cannot be used by applications.\n", + umip_insns[umip_inst]); + /* Do not emulate SLDT, STR or user long mode processes. */ if (umip_inst == UMIP_INST_STR || umip_inst == UMIP_INST_SLDT || user_64bit_mode(regs)) return false; + umip_pr_warning(regs, "For now, expensive software emulation returns the result.\n"); + if (emulate_umip_insn(&insn, umip_inst, dummy_data, &dummy_data_size)) return false; |