x86/entry/64: Really create an error-entry-from-usermode code path
commit cb6f64ed upstream. In 539f5113 ("x86/asm/entry/64: Disentangle error_entry/exit gsbase/ebx/usermode code"), I arranged the code slightly wrong -- IRET faults would skip the code path that was intended to execute on all error entries from user mode. Fix it up. While we're at it, make all the labels in error_entry local. This does not fix a bug, but we'll need it, and it slightly shrinks the code. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/91e17891e49fa3d61357eadc451529ad48143ee1.1435952415.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.16 as dependency of commit 18ec54fd "x86/speculation: Prepare entry code for Spectre v1 swapgs mitigations": - Adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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