From 071ccc966ba5db1ac8f5c24b0faebb37698f68db Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 3 Apr 2018 15:39:26 -0700 Subject: [PATCH] x86/entry/64: Drop idtentry's manual stack switch for user entries For non-paranoid entries, idtentry knows how to switch from the kernel stack to the user stack, as does error_entry. This results in pointless duplication and code bloat. Make idtentry stop thinking about stacks for non-paranoid entries. This reduces text size by 5377 bytes. This goes back to the following commit: 7f2590a110b8 ("x86/entry/64: Use a per-CPU trampoline stack for IDT entries") Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Dominik Brodowski Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/90aab80c1f906e70742eaa4512e3c9b5e62d59d4.1522794757.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/entry_64.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 9b114675fbc0..e237913a056b 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -908,7 +908,7 @@ ENTRY(\sym) pushq $-1 /* ORIG_RAX: no syscall to restart */ .endif - .if \paranoid < 2 + .if \paranoid == 1 testb $3, CS-ORIG_RAX(%rsp) /* If coming from userspace, switch stacks */ jnz .Lfrom_usermode_switch_stack_\@ .endif @@ -955,7 +955,7 @@ ENTRY(\sym) jmp error_exit .endif - .if \paranoid < 2 + .if \paranoid == 1 /* * Entry from userspace. Switch stacks and treat it * as a normal entry. This means that paranoid handlers -- 2.30.2