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Message-ID: <20240802221952.GA737452@thelio-3990X>
Date: Fri, 2 Aug 2024 15:19:52 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc: kernel test robot <lkp@...el.com>,
"Gustavo A. R. Silva" <gustavoars@...nel.org>, llvm@...ts.linux.dev,
oe-kbuild-all@...ts.linux.dev, LKML <linux-kernel@...r.kernel.org>,
Brian Cain <bcain@...cinc.com>, linux-hexagon@...r.kernel.org
Subject: Re: [gustavoars:testing/wfamnae-next20240729-cbc-2 11/18]
include/rdma/uverbs_ioctl.h:643:15: error: static assertion failed due to
requirement '__builtin_offsetof(struct uverbs_attr_bundle, attrs) ==
sizeof(struct uverbs_attr_bundle_hdr)': struct member likely outside of
struct_group_tagged()
On Thu, Aug 01, 2024 at 04:35:59PM -0600, Gustavo A. R. Silva wrote:
>
>
> On 01/08/24 16:14, Nathan Chancellor wrote:
> > On Thu, Aug 01, 2024 at 02:17:50PM -0600, Gustavo A. R. Silva wrote:
> > >
> > >
> > > On 01/08/24 13:08, Nathan Chancellor wrote:
> > > > On Thu, Aug 01, 2024 at 06:47:58AM -0600, Gustavo A. R. Silva wrote:
> > > > >
> > > > >
> > > > > On 01/08/24 05:35, kernel test robot wrote:
> > > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git testing/wfamnae-next20240729-cbc-2
> > > > > > head: df15c862c1b93b6e1f6c90b0d7971f7a6ad66751
> > > > > > commit: e7cd9f429a852fb7e37a706c7d08fc36e7863e06 [11/18] RDMA/uverbs: Use static_assert() to check struct sizes
> > > > > > config: hexagon-randconfig-001-20240801 (https://download.01.org/0day-ci/archive/20240801/202408011956.wscyBwq6-lkp@intel.com/config)
> > > > > > compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project 430b90f04533b099d788db2668176038be38c53b)
> > > > >
> > > > >
> > > > > Clang 20.0.0?? (thinkingface)
> > > >
> > > > Indeed, Clang 19 branched and main is now 20 :)
> > > >
> > > > https://github.com/llvm/llvm-project/commit/8f701b5df0adb3a2960d78ca2ad9cf53f39ba2fe
> > >
> > > Yeah, but is that a stable release?
> >
> > No, but the Intel folks have tested tip of tree LLVM against the kernel
> > for us for a few years now to try and catch issues such as this.
>
> Oh, I see, fine. :)
>
> >
> > > BTW, I don't see GCC reporting the same problem below:
> >
> > Hexagon does not have a GCC backend anymore so it is not going to be
> > possible to do an exact A/B comparison with this configuration but...
> >
> > > > > > > > include/rdma/uverbs_ioctl.h:643:15: error: static assertion failed due to requirement '__builtin_offsetof(struct uverbs_attr_bundle, attrs) == sizeof(struct uverbs_attr_bundle_hdr)': struct member likely outside of struct_group_tagged()
> > > > > > 643 | static_assert(offsetof(struct uverbs_attr_bundle, attrs) == sizeof(struct uverbs_attr_bundle_hdr),
> > > > > > | ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > 644 | "struct member likely outside of struct_group_tagged()");
> > > > > > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > include/linux/stddef.h:16:32: note: expanded from macro 'offsetof'
> > > > > > 16 | #define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER)
> > > > > > | ^
> > > > > > include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
> > > > > > 77 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
> > > > > > | ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
> > > > > > 78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
> > > > > > | ^~~~
> > > > > > include/rdma/uverbs_ioctl.h:643:58: note: expression evaluates to '56 == 52'
> >
> > This seems to give some indication that perhaps there may be some
> > architecture specific here with padding maybe? I seem to recall ARM OABI
> > having something similar. Adding the Hexagon folks/list to get some more
> > clarification. Full warning and context:
> >
> > https://lore.kernel.org/202408011956.wscyBwq6-lkp@intel.com/
> >
> > The problematic section preprocessed since sometimes the macros
> > obfuscate things:
> >
> > struct uverbs_attr_bundle {
> > union {
> > struct {
> > struct ib_udata driver_udata;
> > struct ib_udata ucore;
> > struct ib_uverbs_file *ufile;
> > struct ib_ucontext *context;
> > struct ib_uobject *uobject;
> > unsigned long attr_present[(((UVERBS_API_ATTR_BKEY_LEN) +
> > ((sizeof(long) * 8)) - 1) /
> > ((sizeof(long) * 8)))];
> > };
> > struct uverbs_attr_bundle_hdr {
> > struct ib_udata driver_udata;
> > struct ib_udata ucore;
> > struct ib_uverbs_file *ufile;
> > struct ib_ucontext *context;
> > struct ib_uobject *uobject;
> > unsigned long attr_present[(((UVERBS_API_ATTR_BKEY_LEN) +
> > ((sizeof(long) * 8)) - 1) /
> > ((sizeof(long) * 8)))];
> > } hdr;
> > };
> >
> > struct uverbs_attr attrs[];
> > };
> > _Static_assert(__builtin_offsetof(struct uverbs_attr_bundle, attrs) ==
> > sizeof(struct uverbs_attr_bundle_hdr),
> > "struct member likely outside of struct_group_tagged()");
> >
> > FWIW, I see this with all versions of Clang that the kernel supports
> > with this configuration.
>
> I don't have access to a Clang compiler right now; I wonder if you could
> help me get the output of this command:
>
> pahole -C uverbs_attr_bundle drivers/infiniband/core/rdma_core.o
We disabled CONFIG_DEBUG_INFO_BTF for Hexagon because elfutils does not
support Hexagon relocations but this is built-in for this configuration
so I removed that limitation and ended up with:
$ pahole -C uverbs_attr_bundle vmlinux
struct uverbs_attr_bundle {
union {
struct {
struct ib_udata driver_udata; /* 0 16 */
struct ib_udata ucore; /* 16 16 */
struct ib_uverbs_file * ufile; /* 32 4 */
struct ib_ucontext * context; /* 36 4 */
struct ib_uobject * uobject; /* 40 4 */
unsigned long attr_present[2]; /* 44 8 */
}; /* 0 52 */
struct uverbs_attr_bundle_hdr hdr; /* 0 52 */
}; /* 0 52 */
/* XXX 4 bytes hole, try to pack */
union {
struct {
struct ib_udata driver_udata; /* 0 16 */
struct ib_udata ucore; /* 16 16 */
struct ib_uverbs_file * ufile; /* 32 4 */
struct ib_ucontext * context; /* 36 4 */
struct ib_uobject * uobject; /* 40 4 */
unsigned long attr_present[2]; /* 44 8 */
}; /* 0 52 */
struct uverbs_attr_bundle_hdr hdr; /* 0 52 */
};
struct uverbs_attr attrs[]; /* 56 0 */
/* size: 56, cachelines: 1, members: 2 */
/* sum members: 52, holes: 1, sum holes: 4 */
/* last cacheline: 56 bytes */
};
If you want any other information or want me to test anything, I am more
than happy to do so.
Cheers,
Nathan
> > > > > > 643 | static_assert(offsetof(struct uverbs_attr_bundle, attrs) == sizeof(struct uverbs_attr_bundle_hdr),
> > > > > > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > 644 | "struct member likely outside of struct_group_tagged()");
> > > > > > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
> > > > > > 77 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
> > > > > > | ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
> > > > > > 78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
> > > > > > | ^~~~
> > > > > > 7 warnings and 1 error generated.
> > > > > >
> > > > > >
> > > > > > vim +643 include/rdma/uverbs_ioctl.h
> > > > > >
> > > > > > 630
> > > > > > 631 struct uverbs_attr_bundle {
> > > > > > 632 /* New members MUST be added within the struct_group() macro below. */
> > > > > > 633 struct_group_tagged(uverbs_attr_bundle_hdr, hdr,
> > > > > > 634 struct ib_udata driver_udata;
> > > > > > 635 struct ib_udata ucore;
> > > > > > 636 struct ib_uverbs_file *ufile;
> > > > > > 637 struct ib_ucontext *context;
> > > > > > 638 struct ib_uobject *uobject;
> > > > > > 639 DECLARE_BITMAP(attr_present, UVERBS_API_ATTR_BKEY_LEN);
> > > > > > 640 );
> > > > > > 641 struct uverbs_attr attrs[];
> > > > > > 642 };
> > > > > > > 643 static_assert(offsetof(struct uverbs_attr_bundle, attrs) == sizeof(struct uverbs_attr_bundle_hdr),
> > > > > > 644 "struct member likely outside of struct_group_tagged()");
> > > > > > 645
> > > > > >
> > > > >
> > >
> > > Thanks
> > > --
> > > Gustavo
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