Re: [igt-dev] [PATCH i-g-t v2 2/2] build: provide stub implementation for memfd_create

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Jul 24, 2018 at 03:20:24PM -0700, Lucas De Marchi wrote:
> When libc misses memfd_create(), provide a stub implementation to go
> through the syscall() route. Syscall numbers are provided for platforms
> currently supported by i-g-t only.
> 
> v2: add support to autotools
> 
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> ---
>  configure.ac                  |  3 +++
>  lib/stubs/syscalls/sys/mman.h | 37 +++++++++++++++++++++++++++++++++++
>  meson.build                   |  3 +++
>  3 files changed, 43 insertions(+)
>  create mode 100644 lib/stubs/syscalls/sys/mman.h
> 
> diff --git a/configure.ac b/configure.ac
> index 0a5b0425..416a3240 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -81,6 +81,9 @@ AC_CHECK_FUNCS(timer_create, [], [
>  ])
>  AC_SUBST(TIMER_LIBS)
>  
> +dnl Check for memfd_create
> +AC_CHECK_FUNCS(memfd_create)
> +
>  dnl Check for CPUID
>  cpuid="yes"
>  AC_TRY_LINK([
> diff --git a/lib/stubs/syscalls/sys/mman.h b/lib/stubs/syscalls/sys/mman.h
> new file mode 100644
> index 00000000..2ac2da6a
> --- /dev/null
> +++ b/lib/stubs/syscalls/sys/mman.h
> @@ -0,0 +1,37 @@
> +/* SPDX-License-Identifier: MIT */
> +
> +#pragma once
> +
> +#include_next <sys/mman.h>
> +
> +#if !defined(HAVE_MEMFD_CREATE) || !HAVE_MEMFD_CREATE
> +#include <errno.h>
> +#include <sys/syscall.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +
> +#ifndef __NR_memfd_create
> +#if defined __x86_64__
> +#define __NR_memfd_create 319
> +#elif defined __i386__
> +#define __NR_memfd_create 356
> +#elif defined __arm__
> +#define __NR_memfd_create 385
> +#else
> +#warning "__NR_memfd_create unknown for your architecture"
> +#endif
> +#endif
> +
> +static inline int missing_memfd_create(const char *name, unsigned int flags)
> +{
> +#ifdef __NR_memfd_create
> +	return syscall(__NR_memfd_create, name, flags);
> +#else
> +	errno = ENOSYS;
> +	return -1;
> +#endif
> +}
> +
> +#define memfd_create missing_memfd_create
> +
> +#endif
> diff --git a/meson.build b/meson.build
> index 22118828..63ac6292 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -196,6 +196,9 @@ if cc.has_member('struct sysinfo', 'totalram',
>  	config.set('HAVE_STRUCT_SYSINFO_TOTALRAM', 1)
>  endif
>  
> +have = cc.has_function('memfd_create', prefix : '''#include <sys/mman.h>''', args : '-D_GNU_SOURCE')
> +config.set10('HAVE_MEMFD_CREATE', have)
> +
>  add_project_arguments('-D_GNU_SOURCE', language : 'c')
>  add_project_arguments('-include', 'config.h', language : 'c')
>  
> -- 
> 2.17.1
> 
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