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Diffstat (limited to 'arch')
-rw-r--r--arch/x86_64/kernel/entry.S29
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