* Re: [PATCH v4 02/18] a.out: remove define-only CMAGIC, previously magic number [not found] ` <CAMuHMdWxf=+CnwXT61VvYhcHi093rz=0ftWQXKVviMunzE1HHw@mail.gmail.com> @ 2022-09-26 15:15 ` наб 2022-09-26 16:47 ` Greg KH 0 siblings, 1 reply; 2+ messages in thread From: наб @ 2022-09-26 15:15 UTC (permalink / raw) To: Geert Uytterhoeven Cc: Greg KH, Bagas Sanjaya, Jonathan Corbet, Federico Vaga, Alex Shi, Yanteng Si, Hu Haowen, linux-doc, linux-kernel, linux-doc-tw-discuss, Eric Biederman, Kees Cook, Alexander Viro, Linux MM [-- Attachment #1: Type: text/plain, Size: 3858 bytes --] Hi! On Mon, Sep 26, 2022 at 10:16:02AM +0200, Geert Uytterhoeven wrote: > Thanks for your patch, which is now commit 53c2bd679017277f > ("a.out: remove define-only CMAGIC, previously magic number") in > driver-core/driver-core-next. > > On Fri, Sep 16, 2022 at 12:40 AM наб <nabijaczleweli@nabijaczleweli.xyz> wrote: > > The last user was removed in 5.1 in > > commit 08300f4402ab ("a.out: remove core dumping support") > > but this is part of the UAPI headers, so this may want to either wait > > until a.out is removed entirely, or be removed from the magic number doc > > and silently remain in the header > > Indeed. This is part of uapi, and might break some unknown > userspace, while the gain is limited. Do we really want to reduce > include/uapi/linux/a.out.h piecewise (e.g. N_BADMAG() seems to be > unused, too), instead of keeping it until a.out support is removed > completely? Not really, but it looked like a magic number in the magic-number.rst sense due to the field being "magic" and the unintuitive type naming: I hadn't realised it's part of the on-disk format re-examination shows that it very well may be (have been). > Anyway, even at that point, it might be wise to keep the header file > around, as people have expressed the desire to run a.out binaries > through a userspace-compatibility wrapper. Agreed. Scissor-patch that reverts the removal below. > > A cursory glance on DCS didn't show any user code actually using this > > value > > What is DCS? Debian Code Search; in this case my query was: https://codesearch.debian.net/search?q=%5CbCMAGIC%5Cb&literal=0 There's a few false positives here but all results that are using CMAGIC to mean this CMAGIC (and aren't hurd code copied from linux) just re-define it. > > Documentation/process/magic-number.rst | 1 - > > Documentation/translations/it_IT/process/magic-number.rst | 1 - > > Documentation/translations/zh_CN/process/magic-number.rst | 1 - > > Documentation/translations/zh_TW/process/magic-number.rst | 1 - > > include/uapi/linux/a.out.h | 3 --- > > 5 files changed, 7 deletions(-) > > > > diff --git a/include/uapi/linux/a.out.h b/include/uapi/linux/a.out.h > > index 5fafde3798e5..bb15da96df2a 100644 > > --- a/include/uapi/linux/a.out.h > > +++ b/include/uapi/linux/a.out.h > > @@ -70,9 +70,6 @@ enum machine_type { > > The first page is unmapped to help trap NULL pointer references */ > > #define QMAGIC 0314 > > > > -/* Code indicating core file. */ > > -#define CMAGIC 0421 > > - > > #if !defined (N_BADMAG) > > #define N_BADMAG(x) (N_MAGIC(x) != OMAGIC \ > > && N_MAGIC(x) != NMAGIC \ > > Gr{oetje,eeting}s, > Geert Best, наб -- >8 -- Subject: [PATCH] a.out: restore CMAGIC Part of UAPI and the on-disk format: this means that it's not a magic number per magic-number.rst, and it's best to leave it untouched to avoid breaking userspace and suffer the same fate as a.out in general Fixes: commit 53c2bd679017 ("a.out: remove define-only CMAGIC, previously magic number") Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> --- include/uapi/linux/a.out.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/uapi/linux/a.out.h b/include/uapi/linux/a.out.h index bb15da96df2a..5fafde3798e5 100644 --- a/include/uapi/linux/a.out.h +++ b/include/uapi/linux/a.out.h @@ -70,6 +70,9 @@ enum machine_type { The first page is unmapped to help trap NULL pointer references */ #define QMAGIC 0314 +/* Code indicating core file. */ +#define CMAGIC 0421 + #if !defined (N_BADMAG) #define N_BADMAG(x) (N_MAGIC(x) != OMAGIC \ && N_MAGIC(x) != NMAGIC \ -- 2.30.2 [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 833 bytes --] ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v4 02/18] a.out: remove define-only CMAGIC, previously magic number 2022-09-26 15:15 ` [PATCH v4 02/18] a.out: remove define-only CMAGIC, previously magic number наб @ 2022-09-26 16:47 ` Greg KH 0 siblings, 0 replies; 2+ messages in thread From: Greg KH @ 2022-09-26 16:47 UTC (permalink / raw) To: наб Cc: Geert Uytterhoeven, Bagas Sanjaya, Jonathan Corbet, Federico Vaga, Alex Shi, Yanteng Si, Hu Haowen, linux-doc, linux-kernel, linux-doc-tw-discuss, Eric Biederman, Kees Cook, Alexander Viro, Linux MM On Mon, Sep 26, 2022 at 05:15:54PM +0200, наб wrote: > Hi! > > On Mon, Sep 26, 2022 at 10:16:02AM +0200, Geert Uytterhoeven wrote: > > Thanks for your patch, which is now commit 53c2bd679017277f > > ("a.out: remove define-only CMAGIC, previously magic number") in > > driver-core/driver-core-next. > > > > On Fri, Sep 16, 2022 at 12:40 AM наб <nabijaczleweli@nabijaczleweli.xyz> wrote: > > > The last user was removed in 5.1 in > > > commit 08300f4402ab ("a.out: remove core dumping support") > > > but this is part of the UAPI headers, so this may want to either wait > > > until a.out is removed entirely, or be removed from the magic number doc > > > and silently remain in the header > > > > Indeed. This is part of uapi, and might break some unknown > > userspace, while the gain is limited. Do we really want to reduce > > include/uapi/linux/a.out.h piecewise (e.g. N_BADMAG() seems to be > > unused, too), instead of keeping it until a.out support is removed > > completely? > > Not really, but it looked like a magic number in the magic-number.rst > sense due to the field being "magic" and the unintuitive type naming: > I hadn't realised it's part of the on-disk format > re-examination shows that it very well may be (have been). > > > Anyway, even at that point, it might be wise to keep the header file > > around, as people have expressed the desire to run a.out binaries > > through a userspace-compatibility wrapper. > > Agreed. Scissor-patch that reverts the removal below. > > > > A cursory glance on DCS didn't show any user code actually using this > > > value > > > > What is DCS? > > Debian Code Search; in this case my query was: > https://codesearch.debian.net/search?q=%5CbCMAGIC%5Cb&literal=0 > > There's a few false positives here but all results that are using CMAGIC > to mean this CMAGIC (and aren't hurd code copied from linux) > just re-define it. > > > > Documentation/process/magic-number.rst | 1 - > > > Documentation/translations/it_IT/process/magic-number.rst | 1 - > > > Documentation/translations/zh_CN/process/magic-number.rst | 1 - > > > Documentation/translations/zh_TW/process/magic-number.rst | 1 - > > > include/uapi/linux/a.out.h | 3 --- > > > 5 files changed, 7 deletions(-) > > > > > > diff --git a/include/uapi/linux/a.out.h b/include/uapi/linux/a.out.h > > > index 5fafde3798e5..bb15da96df2a 100644 > > > --- a/include/uapi/linux/a.out.h > > > +++ b/include/uapi/linux/a.out.h > > > @@ -70,9 +70,6 @@ enum machine_type { > > > The first page is unmapped to help trap NULL pointer references */ > > > #define QMAGIC 0314 > > > > > > -/* Code indicating core file. */ > > > -#define CMAGIC 0421 > > > - > > > #if !defined (N_BADMAG) > > > #define N_BADMAG(x) (N_MAGIC(x) != OMAGIC \ > > > && N_MAGIC(x) != NMAGIC \ > > > > Gr{oetje,eeting}s, > > Geert > > Best, > наб > > -- >8 -- > Subject: [PATCH] a.out: restore CMAGIC > > Part of UAPI and the on-disk format: > this means that it's not a magic number per magic-number.rst, > and it's best to leave it untouched to avoid breaking userspace > and suffer the same fate as a.out in general > > Fixes: commit 53c2bd679017 ("a.out: remove define-only CMAGIC, > previously magic number") > Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> > --- > include/uapi/linux/a.out.h | 3 +++ > 1 file changed, 3 insertions(+) Thanks, I'll take this through my tree as it has the offending commit in it. greg k-h ^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] ` <9cbea062df7125ef43e2e0b2a67ede6ad1c5f27e.1663280877.git.nabijaczleweli@nabijaczleweli.xyz>
[not found] ` <CAMuHMdWxf=+CnwXT61VvYhcHi093rz=0ftWQXKVviMunzE1HHw@mail.gmail.com>
2022-09-26 15:15 ` [PATCH v4 02/18] a.out: remove define-only CMAGIC, previously magic number наб
2022-09-26 16:47 ` Greg KH
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