Messages in this thread | | | Date | Tue, 7 Apr 2020 10:27:45 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH] arm64: armv8_deprecated: Fix undef_hook mask for thumb setend |
| |
On Mon, Apr 06, 2020 at 04:16:05PM +0200, Fredrik Strupe wrote: > Use a full 32-bit mask to prevent accidental matchings of thumb32 > instructions where the second half-word is equal to the thumb16 setend > encoding. > > This fixes the same problem as the following patch: > > https://lkml.org/lkml/2020/3/16/341
This link is not guaranteed to be stable and the commit should have the full description rather than referring to another email.
> but for setend emulation instead. > > Signed-off-by: Fredrik Strupe <fredrik@strupe.net>
It also needs Fixes: and Cc: stable tags.
> --- > arch/arm64/kernel/armv8_deprecated.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c > index 9d3442d62..8c06dfee0 100644 > --- a/arch/arm64/kernel/armv8_deprecated.c > +++ b/arch/arm64/kernel/armv8_deprecated.c > @@ -609,7 +609,7 @@ static struct undef_hook setend_hooks[] = { > }, > { > /* Thumb mode */ > - .instr_mask = 0x0000fff7, > + .instr_mask = 0xfffffff7, > .instr_val = 0x0000b650,
I can see how this could happen but it would be useful to provide a concrete example in the commit log.
The instruction opcode built by call_undef_hook() first reads a u16 as a T16 instruction and the above should be fine. However, if this looks like a T32 opcode, it reads a subsequent u16 which becomes the lowest half-word and the above mask/val may inadvertently match it.
The patch looks fine to me as long as you update the commit log.
Thanks.
-- Catalin
| |