1 files changed, 17 insertions, 16 deletions

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 54b1b0468b2b..670306f588bf 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1256,31 +1256,32 @@ END(paranoid_entry)
 ENTRY(paranoid_exit)
         UNWIND_HINT_REGS
         DISABLE_INTERRUPTS(CLBR_ANY)
-        TRACE_IRQS_OFF_DEBUG
 
-        /* Handle GS depending on FSGSBASE availability */
-        ALTERNATIVE "jmp .Lparanoid_exit_checkgs", "nop",X86_FEATURE_FSGSBASE
+        /*
+         * The order of operations is important.  IRQ tracing requires
+         * kernel GSBASE and CR3.  RESTORE_CR3 requires kernel GS base.
+         *
+         * NB to anyone to tries to optimize this code: this code does
+         * not execute at all for exceptions coming from user mode.  Those
+         * exceptions go through error_exit instead.
+         */
+        TRACE_IRQS_IRETQ_DEBUG
+        RESTORE_CR3     scratch_reg=%rax save_reg=%r14
+
+        /* Handle the three GSBASE cases. */
+        ALTERNATIVE "jmp .Lparanoid_exit_checkgs", "", X86_FEATURE_FSGSBASE
 
         /* With FSGSBASE enabled, unconditionally restore GSBASE */
         wrgsbase        %rbx
-        jmp     .Lparanoid_exit_no_swapgs;
+        jmp     restore_regs_and_return_to_kernel
 
 .Lparanoid_exit_checkgs:
         /* On non-FSGSBASE systems, conditionally do SWAPGS */
         testl   %ebx, %ebx
-        jnz     .Lparanoid_exit_no_swapgs
-        TRACE_IRQS_IRETQ
-        /* Always restore stashed CR3 value (see paranoid_entry) */
-        RESTORE_CR3     scratch_reg=%rbx save_reg=%r14
-        SWAPGS_UNSAFE_STACK
-        jmp     .Lparanoid_exit_restore
-
-.Lparanoid_exit_no_swapgs:
-        TRACE_IRQS_IRETQ_DEBUG
-        /* Always restore stashed CR3 value (see paranoid_entry) */
-        RESTORE_CR3     scratch_reg=%rbx save_reg=%r14
+        jnz     restore_regs_and_return_to_kernel
 
-.Lparanoid_exit_restore:
+        /* We are returning to a context with user GSBASE. */
+        SWAPGS_UNSAFE_STACK
         jmp     restore_regs_and_return_to_kernel
 END(paranoid_exit)