On Fri, Mar 3, 2017 at 1:41 PM, Ricardo Neri <ricardo.neri-calderon(a)linux.intel.com> wrote:
fixup_umip_exception will be called from do_general_protection. If the former returns false, the latter will issue a SIGSEGV with SEND_SIG_PRIV. However, when emulation is successful but the emulated result cannot be copied to user space memory, it is more accurate to issue a SIGSEGV with SEGV_MAPERR with the offending address. A new function is inspired in force_sig_info_fault is introduced to model the page fault.
Signed-off-by: Ricardo Neri <ricardo.neri-calderon(a)linux.intel.com> --- arch/x86/kernel/umip.c | 45 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 43 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c index e932f40..5b6a7cf 100644 --- a/arch/x86/kernel/umip.c +++ b/arch/x86/kernel/umip.c @@ -170,6 +170,41 @@ static int __emulate_umip_insn(struct insn *insn, enum umip_insn umip_inst, }
/** + * __force_sig_info_umip_fault - Force a SIGSEGV with SEGV_MAPERR + * @address: Address that caused the signal + * @regs: Register set containing the instruction pointer + * + * Force a SIGSEGV signal with SEGV_MAPERR as the error code. This function is + * intended to be used to provide a segmentation fault when the result of the + * UMIP emulation could not be copied to the user space memory. + * + * Return: none + */ +static void __force_sig_info_umip_fault(void __user *address, + struct pt_regs *regs) +{ + siginfo_t info; + struct task_struct *tsk = current; + + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV)) { + printk_ratelimited("%s[%d] umip emulation segfault ip:%lx sp:%lx error:%lx in %lx\n", + tsk->comm, task_pid_nr(tsk), regs->ip, + regs->sp, UMIP_PF_USER | UMIP_PF_WRITE, + regs->ip); + } + + tsk->thread.cr2 = (unsigned long)address; + tsk->thread.error_code = UMIP_PF_USER | UMIP_PF_WRITE;
Please just move enum x86_pf_error_code into a header and rename the fields X86_PF_USER, etc rather than duplicating it. --Andy