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Groups > linux.kernel > #1593033
| From | "H. Peter Anvin" <hpa@zytor.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 1/3] futex: remove duplicated code |
| Date | 2017-03-06 10:20 +0100 |
| Message-ID | <thWYb-64J-63@gated-at.bofh.it> (permalink) |
| References | (2 earlier) <thnxn-5re-7@gated-at.bofh.it> <thpzb-6Um-13@gated-at.bofh.it> <thr7X-81G-1@gated-at.bofh.it> <thrrj-89Z-5@gated-at.bofh.it> <thWv7-5E6-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 03/06/17 00:46, Jiri Slaby wrote:
>
> static int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
> {
> - int op = (encoded_op >> 28) & 7;
> - int cmp = (encoded_op >> 24) & 15;
> - int oparg = (encoded_op << 8) >> 20;
> - int cmparg = (encoded_op << 20) >> 20;
> + int op = (encoded_op & 0x70000000) >> 28;
> + int cmp = (encoded_op & 0x0f000000) >> 24;
> + int oparg = sign_extend32((encoded_op & 0x00fff000) >> 12, 12);
> + int cmparg = sign_extend32(encoded_op & 0x00000fff, 12);
> int oldval, ret;
>
At least in the sign-extend case the mask is unnecessary.
This is why it would be nice to have both sign and zero extend for symmetry.
-hpa
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[PATCH 1/3] futex: remove duplicated code Jiri Slaby <jslaby@suse.cz> - 2017-03-03 13:40 +0100
[PATCH 2/3] futex: fix decoding of operation Jiri Slaby <jslaby@suse.cz> - 2017-03-03 19:30 +0100
[PATCH 3/3] futex: make the encoded_op decoding readable Jiri Slaby <jslaby@suse.cz> - 2017-03-03 19:30 +0100
Re: [PATCH 3/3] futex: make the encoded_op decoding readable Jiri Slaby <jslaby@suse.cz> - 2017-03-05 09:00 +0100
Re: [PATCH 1/3] futex: remove duplicated code Heiko Carstens <heiko.carstens@de.ibm.com> - 2017-03-03 21:10 +0100
Re: [PATCH 1/3] futex: remove duplicated code Michael Ellerman <mpe@ellerman.id.au> - 2017-03-04 14:00 +0100
Re: [PATCH 1/3] futex: remove duplicated code Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-04 14:20 +0100
Re: [PATCH 1/3] futex: remove duplicated code "H. Peter Anvin" <hpa@zytor.com> - 2017-03-04 20:30 +0100
Re: [PATCH 1/3] futex: remove duplicated code Stafford Horne <shorne@gmail.com> - 2017-03-04 22:40 +0100
Re: [PATCH 1/3] futex: remove duplicated code "H. Peter Anvin" <hpa@zytor.com> - 2017-03-05 00:20 +0100
Re: [PATCH 1/3] futex: remove duplicated code Stafford Horne <shorne@gmail.com> - 2017-03-05 00:40 +0100
Re: [PATCH 1/3] futex: remove duplicated code Jiri Slaby <jslaby@suse.cz> - 2017-03-06 09:50 +0100
Re: [PATCH 1/3] futex: remove duplicated code "H. Peter Anvin" <hpa@zytor.com> - 2017-03-06 10:20 +0100
Re: [PATCH 1/3] futex: remove duplicated code Geert Uytterhoeven <geert@linux-m68k.org> - 2017-03-06 15:20 +0100
Re: [PATCH 1/3] futex: remove duplicated code "H. Peter Anvin" <hpa@zytor.com> - 2017-03-05 00:20 +0100
Re: [PATCH 1/3] futex: remove duplicated code Rob Landley <rob@landley.net> - 2017-03-09 05:20 +0100
Re: [PATCH 1/3] futex: remove duplicated code "H. Peter Anvin" <hpa@zytor.com> - 2017-03-09 06:10 +0100
Re: [PATCH 1/3] futex: remove duplicated code Rich Felker <dalias@libc.org> - 2017-03-09 23:50 +0100
Re: [PATCH 1/3] futex: remove duplicated code Rich Felker <dalias@libc.org> - 2017-03-06 03:20 +0100
Re: [PATCH 1/3] futex: remove duplicated code Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2017-03-09 23:50 +0100
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