Re: [Buildroot] [PATCH] package/glibc: add a patch to fix build issue in kernels >= 3.15 and < 5.1 on Microblaze

["Yann E. MORIN" <yann.morin.1998@free.fr>]

Thomas, All,

On 2021-12-26 11:45 +0100, Thomas Petazzoni spake thusly:
> As explained in the patch itself, there is a bug in the handling of
> __pselect32() in glibc for the Microblaze architecture. There a
> special Microblaze variant that was added to support kernels older
> than < 3.15, but it "hides" a generic implementation that is needed to
> support kernels newer than 3.15 but older than 5.1 (which is when the
> time64 support for 32-bit architectures was added, making __pselect32
> no longer needed).
> 
> This bug causes a glibc build failure for kernels >= 3.15 but < 5.1,
> on Microblaze.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Applied to master, thanks.

Regards,
Yann E. MORIN.

> ---
>  ...v-linux-microblaze-pselect32.c-add-m.patch | 85 +++++++++++++++++++
>  1 file changed, 85 insertions(+)
>  create mode 100644 package/glibc/2.34-9-g9acab0bba6a5a57323b1f94bf95b21618a9e5aa4/0001-sysdeps-unix-sysv-linux-microblaze-pselect32.c-add-m.patch
> 
> diff --git a/package/glibc/2.34-9-g9acab0bba6a5a57323b1f94bf95b21618a9e5aa4/0001-sysdeps-unix-sysv-linux-microblaze-pselect32.c-add-m.patch b/package/glibc/2.34-9-g9acab0bba6a5a57323b1f94bf95b21618a9e5aa4/0001-sysdeps-unix-sysv-linux-microblaze-pselect32.c-add-m.patch
> new file mode 100644
> index 0000000000..3597cd6a11
> --- /dev/null
> +++ b/package/glibc/2.34-9-g9acab0bba6a5a57323b1f94bf95b21618a9e5aa4/0001-sysdeps-unix-sysv-linux-microblaze-pselect32.c-add-m.patch
> @@ -0,0 +1,85 @@
> +From af06fe63f9babb6d0179ae5d7d9245daada6bf56 Mon Sep 17 00:00:00 2001
> +From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> +Date: Sun, 26 Dec 2021 10:30:01 +0100
> +Subject: [PATCH] sysdeps/unix/sysv/linux/microblaze/pselect32.c: add missing
> + implementation when !__ASSUME_TIME64_SYSCALLS
> +
> +In commit a92f4e6299fe0e3cb6f77e79de00817aece501ce ("linux: Add time64
> +pselect support"), a Microblaze specific implementation of
> +__pselect32() was added to cover the case of kernels < 3.15 which lack
> +the pselect6 system call.
> +
> +This new file sysdeps/unix/sysv/linux/microblaze/pselect32.c takes
> +precedence over the default implementation
> +sysdeps/unix/sysv/linux/pselect32.c.
> +
> +However sysdeps/unix/sysv/linux/pselect32.c provides an implementation
> +of __pselect32() which is needed when __ASSUME_TIME64_SYSCALLS is not
> +defined. On Microblaze, which is a 32-bit architecture,
> +__ASSUME_TIME64_SYSCALLS is only true for kernels >= 5.1.
> +
> +Due to sysdeps/unix/sysv/linux/microblaze/pselect32.c taking
> +precedence over sysdeps/unix/sysv/linux/pselect32.c, it means that
> +when we are with a kernel >= 3.15 but < 5.1, we need a __pselect32()
> +implementation, but sysdeps/unix/sysv/linux/microblaze/pselect32.c
> +doesn't provide it, and sysdeps/unix/sysv/linux/pselect32.c which
> +would provide it is not compiled in.
> +
> +This causes the following build failure on Microblaze with for example
> +Linux kernel headers 4.9:
> +
> +/home/thomas/buildroot/buildroot/output/host/lib/gcc/microblazeel-buildroot-linux-gnu/10.3.0/../../../../microblazeel-buildroot-linux-gnu/bin/ld: /home/thomas/buildroot/buildroot/output/build/glibc-2.34-9-g9acab0bba6a5a57323b1f94bf95b21618a9e5aa4/build/libc_pic.os: in function `__pselect64':
> +(.text+0x120b44): undefined reference to `__pselect32'
> +collect2: error: ld returned 1 exit status
> +
> +To fix this, we take a crude approach: replicate in
> +sysdeps/unix/sysv/linux/microblaze/pselect32.c the
> +!__ASSUME_TIME64_SYSCALLS implementation that is already in
> +sysdeps/unix/sysv/linux/pselect32.c.
> +
> +Upstream: https://sourceware.org/pipermail/libc-alpha/2021-December/134635.html
> +Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> +---
> + .../unix/sysv/linux/microblaze/pselect32.c    | 22 +++++++++++++++++--
> + 1 file changed, 20 insertions(+), 2 deletions(-)
> +
> +diff --git a/sysdeps/unix/sysv/linux/microblaze/pselect32.c b/sysdeps/unix/sysv/linux/microblaze/pselect32.c
> +index 70b7b52a48..6b6b3e8a2e 100644
> +--- a/sysdeps/unix/sysv/linux/microblaze/pselect32.c
> ++++ b/sysdeps/unix/sysv/linux/microblaze/pselect32.c
> +@@ -22,7 +22,25 @@
> + #include <sys/poll.h>
> + #include <sysdep-cancel.h>
> + 
> +-#ifndef __ASSUME_PSELECT
> ++#if !defined(__ASSUME_TIME64_SYSCALLS)
> ++int
> ++__pselect32 (int nfds, fd_set *readfds, fd_set *writefds,
> ++	     fd_set *exceptfds, const struct __timespec64 *timeout,
> ++	     const sigset_t *sigmask)
> ++{
> ++  struct timespec ts32, *pts32 = NULL;
> ++  if (timeout != NULL)
> ++    {
> ++      ts32 = valid_timespec64_to_timespec (*timeout);
> ++      pts32 = &ts32;
> ++    }
> ++
> ++  return SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds,
> ++			 pts32,
> ++			 ((__syscall_ulong_t[]){ (uintptr_t) sigmask,
> ++						 __NSIG_BYTES }));
> ++}
> ++#elif !defined(__ASSUME_PSELECT)
> + int
> + __pselect32 (int nfds, fd_set *readfds, fd_set *writefds,
> + 	     fd_set *exceptfds, const struct __timespec64 *timeout,
> +@@ -57,4 +75,4 @@ __pselect32 (int nfds, fd_set *readfds, fd_set *writefds,
> + 
> +   return ret;
> + }
> +-#endif /* __ASSUME_PSELECT  */
> ++#endif
> +-- 
> +2.31.1
> +
> -- 
> 2.31.1
> 
> _______________________________________________
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> buildroot@buildroot.org
> https://lists.buildroot.org/mailman/listinfo/buildroot

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