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Subject[PATCH] x86/entry/64: Drop idtentry's manual stack switch for user entries
Date
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 commit 7f2590a110b8 ("x86/entry/64: Use a per-CPU
trampoline stack for IDT entries").

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---

Hi all-

I have more cleanups in the works, but this is enough of I win by itself
that I wanted to get it out there.

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
--
2.14.3
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