On Tue, 21 Apr 2020 17:41:59 +0200 Christoph Hellwig [off-list ref] wrote:

To remove the use of set_fs in the coredump code there needs to be a
way to convert a kernel siginfo to a userspace compat siginfo.

Call that function copy_siginfo_to_compat and factor it out of
copy_siginfo_to_user32.

The existence of x32 complicates this code.  On x32 SIGCHLD uses 64bit
times for utime and stime.  As only SIGCHLD is affected and SIGCHLD
never causes a coredump I have avoided handling that case.

x86_64 allmodconfig:

kernel/signal.c: In function 'copy_siginfo_to_external32':
kernel/signal.c:3299:7: error: 'x32_ABI' undeclared (first use in this function); did you mean 'CTL_ABI'?
   if (x32_ABI) {
       ^~~~~~~

I looked at fixing it but surely this sort of thing:


int copy_siginfo_to_user32(struct compat_siginfo __user *to,
			   const struct kernel_siginfo *from)
#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
{
	return __copy_siginfo_to_user32(to, from, in_x32_syscall());
}
int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
			     const struct kernel_siginfo *from, bool x32_ABI)
#endif
{
	...


is too ugly to live?