diff options
| -rw-r--r-- | arch/x86_64/kernel/entry.S | 29 |
1 files changed, 11 insertions, 18 deletions
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S index 7c10e9009d6..22cb6ee074b 100644 --- a/arch/x86_64/kernel/entry.S +++ b/arch/x86_64/kernel/entry.S @@ -178,6 +178,12 @@ rff_trace: * Interrupts are off on entry. * Only called from user space. * + * EM64T CPUs have somewhat weird error reporting for non canonical RIPs in SYSRET. + * We can't handle any exceptions there because the exception handler would + * end up running on the user stack which is unsafe. To avoid problems + * any code that might end up with a user touched pt_regs should return + * using int_ret_from_syscall. + * * XXX if we had a free scratch register we could save the RSP into the stack frame * and report it properly in ps. Unfortunately we haven't. */ @@ -254,7 +260,9 @@ sysret_signal: xorl %esi,%esi # oldset -> arg2 call ptregscall_common 1: movl $_TIF_NEED_RESCHED,%edi - jmp sysret_check + /* Stack frame might have been changed. The IRET path does + some additional checks to handle this */ + jmp int_with_check badsys: movq $-ENOSYS,RAX-ARGOFFSET(%rsp) @@ -280,7 +288,8 @@ tracesys: call syscall_trace_leave RESTORE_TOP_OF_STACK %rbx RESTORE_REST - jmp ret_from_sys_call + /* Stack frame might have been changed. Use the more careful IRET path */ + jmp int_ret_from_sys_call CFI_ENDPROC /* @@ -408,25 +417,9 @@ ENTRY(stub_execve) CFI_ADJUST_CFA_OFFSET -8 CFI_REGISTER rip, r11 SAVE_REST - movq %r11, %r15 - CFI_REGISTER rip, r15 FIXUP_TOP_OF_STACK %r11 call sys_execve - GET_THREAD_INFO(%rcx) - bt $TIF_IA32,threadinfo_flags(%rcx) - CFI_REMEMBER_STATE - jc exec_32bit RESTORE_TOP_OF_STACK %r11 - movq %r15, %r11 - CFI_REGISTER rip, r11 - RESTORE_REST - pushq %r11 - CFI_ADJUST_CFA_OFFSET 8 - CFI_REL_OFFSET rip, 0 - ret - -exec_32bit: - CFI_RESTORE_STATE movq %rax,RAX(%rsp) RESTORE_REST jmp int_ret_from_sys_call |