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Commit 532826f3 authored by Michael Weiser's avatar Michael Weiser Committed by Will Deacon
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arm64: Mirror arm for unimplemented compat syscalls 



Mirror arm behaviour for unimplemented syscalls: Below 2048 return
-ENOSYS, above 2048 raise SIGILL.

Signed-off-by: default avatarMichael Weiser <michael.weiser@gmx.de>
[will: Tweak die string to identify as compat syscall]
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 4a3928c6

arch/arm64/kernel/sys_compat.c

+20 −1
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/uaccess.h>



#include <asm/cacheflush.h>

#include <asm/system_misc.h>

#include <asm/unistd.h>



static long
@@ -67,6 +68,7 @@ do_compat_cache_op(unsigned long start, unsigned long end, int flags) 
 */

long compat_arm_syscall(struct pt_regs *regs)

{

	siginfo_t info;

	unsigned int no = regs->regs[7];



	switch (no) {
@@ -99,6 +101,23 @@ long compat_arm_syscall(struct pt_regs *regs) 
		return 0;



	default:

		/*

		 * Calls 9f00xx..9f07ff are defined to return -ENOSYS

		 * if not implemented, rather than raising SIGILL. This

		 * way the calling program can gracefully determine whether

		 * a feature is supported.

		 */

		if ((no & 0xffff) <= 0x7ff)

			return -ENOSYS;

		break;

	}



	info.si_signo = SIGILL;

	info.si_errno = 0;

	info.si_code  = ILL_ILLTRP;

	info.si_addr  = (void __user *)instruction_pointer(regs) -

			 (compat_thumb_mode(regs) ? 2 : 4);



	arm64_notify_die("Oops - bad compat syscall(2)", regs, &info, no);

	return 0;

}