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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:

  7f2590a110 ("x86/entry/64: Use a per-CPU trampoline stack for IDT entries")

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/90aab80c1f906e70742eaa4512e3c9b5e62d59d4.1522794757.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2018-04-03 15:39:26 -07:00 committed by Ingo Molnar
parent 9820e1c337
commit 071ccc966b
1 changed files with 2 additions and 2 deletions
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4
arch/x86/entry/entry_64.S
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@ -908,7 +908,7 @@ ENTRY(\sym)
pushq $-1 /* ORIG_RAX: no syscall to restart */ pushq $-1 /* ORIG_RAX: no syscall to restart */
.endif .endif
.if \paranoid < 2 .if \paranoid == 1
testb $3, CS-ORIG_RAX(%rsp) /* If coming from userspace, switch stacks */ testb $3, CS-ORIG_RAX(%rsp) /* If coming from userspace, switch stacks */
jnz .Lfrom_usermode_switch_stack_\@ jnz .Lfrom_usermode_switch_stack_\@
.endif .endif
@ -955,7 +955,7 @@ ENTRY(\sym)
jmp error_exit jmp error_exit
.endif .endif
.if \paranoid < 2 .if \paranoid == 1
/* /*
* Entry from userspace. Switch stacks and treat it * Entry from userspace. Switch stacks and treat it
* as a normal entry. This means that paranoid handlers * as a normal entry. This means that paranoid handlers