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-rw-r--r--arch/x86_64/kernel/entry.S12
1 files changed, 10 insertions, 2 deletions
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 10ec27b607f..c946e4fe67a 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -180,6 +180,10 @@ rff_trace:
*
* 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.
+ *
+ * When user can change the frames always force IRET. That is because
+ * it deals with uncanonical addresses better. SYSRET has trouble
+ * with them due to bugs in both AMD and Intel CPUs.
*/
ENTRY(system_call)
@@ -254,7 +258,10 @@ sysret_signal:
xorl %esi,%esi # oldset -> arg2
call ptregscall_common
1: movl $_TIF_NEED_RESCHED,%edi
- jmp sysret_check
+ /* Use IRET because user could have changed frame. This
+ works because ptregscall_common has called FIXUP_TOP_OF_STACK. */
+ cli
+ jmp int_with_check
badsys:
movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
@@ -280,7 +287,8 @@ tracesys:
call syscall_trace_leave
RESTORE_TOP_OF_STACK %rbx
RESTORE_REST
- jmp ret_from_sys_call
+ /* Use IRET because user could have changed frame */
+ jmp int_ret_from_sys_call
CFI_ENDPROC
/*