Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 2 Jul 2015 08:33:05 -0700 | Subject | Re: [PATCH v4 10/17] x86/entry/64: Really create an error-entry-from-usermode code path |
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On Thu, Jul 2, 2015 at 3:25 AM, Borislav Petkov <bp@alien8.de> wrote: > On Mon, Jun 29, 2015 at 12:33:42PM -0700, Andy Lutomirski wrote: >> In 539f51136500 ("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. >> >> 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> >> --- >> arch/x86/entry/entry_64.S | 12 ++++++++---- >> 1 file changed, 8 insertions(+), 4 deletions(-) >> >> diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S >> index 141a5d49dddc..cd9cbc62159c 100644 >> --- a/arch/x86/entry/entry_64.S >> +++ b/arch/x86/entry/entry_64.S >> @@ -1145,9 +1145,14 @@ ENTRY(error_entry) >> testb $3, CS+8(%rsp) >> jz error_kernelspace >> >> - /* We entered from user mode */ >> +error_entry_from_usermode_swapgs: >> + /* >> + * We entered from user mode or we're pretending to have entered >> + * from user mode due to an IRET fault. >> + */ >> SWAPGS >> >> +error_entry_from_usermode_after_swapgs: >> error_entry_done: > > Why the second label?
"Migrate error and interrupt exit work to C" puts code between those labels. I could squash the patches together to make it less mysterious.
> > Also, please make all those labels local by prefixing them with .L > because they appear unnecesasrily in objdump output as global symbols.
Will do.
> > $ objdump -d vmlinux | grep -E "^[0-9a-f]+ <(error_entry_\w*|error_kernelspace|bstep_iret|error_bad_iret)" > ffffffff8167a4a8 <error_entry_from_usermode_swapgs>: > ffffffff8167a4ab <error_entry_done>: > ffffffff8167a4b1 <error_kernelspace>: > ffffffff8167a4e0 <bstep_iret>: > ffffffff8167a4e8 <error_bad_iret>: > > Oh, and shorter please :) >
I'll try to think of a good shorter name. No promises :)
--Andy
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