Linux: Switch back to assembly syscall wrapper for prctl (bug 29770)

Commit ff026950e280bc3e9487b41b460fb31bc5b57721 ("Add a C wrapper for
prctl [BZ #25896]") replaced the assembler wrapper with a C function.
However, on powerpc64le-linux-gnu, the C variadic function
implementation requires extra work in the caller to set up the
parameter save area.  Calling a function that needs a parameter save
area without one (because the prototype used indicates the function is
not variadic) corrupts the caller's stack.   The Linux manual pages
project documents prctl as a non-variadic function.  This has resulted
in various projects over the years using non-variadic prototypes,
including the sanitizer libraries in LLVm and GCC (GCC PR 113728).

This commit switches back to the assembler implementation on most
targets and only keeps the C implementation for x86-64 x32.

Also add the __prctl_time64 alias from commit
b39ffab860cd743a82c91946619f1b8158b0b65e ("Linux: Add time64 alias for
prctl") to sysdeps/unix/sysv/linux/syscalls.list; it was not yet
present in commit ff026950e280bc3e9487b41b460fb31bc5b57721.

This restores the old ABI on powerpc64le-linux-gnu, thus fixing
bug 29770.

Reviewed-By: Simon Chopin <simon.chopin@canonical.com>

diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index 73e941ef894cd72cf366f44501d23adc0f07e621..9ac42c3436dd1520a0db883b31e4456778b9931e 100644 (file)
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -46,6 +46,7 @@ open_tree     EXTRA   open_tree       i:isU   open_tree
 pipe2          -       pipe2           i:fi    __pipe2         pipe2
 pidfd_open     EXTRA   pidfd_open      i:iU    pidfd_open
 pidfd_getfd    EXTRA   pidfd_getfd     i:iiU   pidfd_getfd
+prctl          EXTRA   prctl           i:iiiii __prctl         prctl __prctl_time64
 pivot_root     EXTRA   pivot_root      i:ss    pivot_root
 pidfd_send_signal      EXTRA   pidfd_send_signal       i:iiPU  pidfd_send_signal
 process_madvise EXTRA   process_madvise i:iPniU process_madvise

diff --git a/sysdeps/unix/sysv/linux/prctl.c b/sysdeps/unix/sysv/linux/x86_64/x32/prctl.c
similarity index 93%
rename from sysdeps/unix/sysv/linux/prctl.c
rename to sysdeps/unix/sysv/linux/x86_64/x32/prctl.c
index 52d234ea0df4cc4851e4f5ce0b6962d4dce1f641..4bf1b479a07c6e8f2c7f3ef3025738c68429eb03 100644 (file)
--- a/sysdeps/unix/sysv/linux/prctl.c
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/prctl.c
@@ -1,4 +1,4 @@
-/* prctl - Linux specific syscall.
+/* prctl - Linux specific syscall.  x86-64 x32 version.
    Copyright (C) 2020-2024 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -40,6 +40,3 @@ __prctl (int option, ...)
 
 libc_hidden_def (__prctl)
 weak_alias (__prctl, prctl)
-#if __TIMESIZE != 64
-weak_alias (__prctl, __prctl_time64)
-#endif