Commit d95bc250 authored Sep 19, 2013 by Will Deacon Committed by Russell King Sep 21, 2013

ARM: 7839/1: entry: fix tracing of ARM-private syscalls



Commit 377747c4 ("ARM: entry: allow ARM-private syscalls to be
restarted") reworked the low-level syscall dispatcher to allow
restarting of ARM-private syscalls. Unfortunately, this relocated the
label used to dispatch a private syscall from the trace path, so that
the invocation would be bypassed altogether!

This causes applications to fail under strace as soon as they rely on
a private syscall (e.g. set_tls):

  set_tls(0xb6fad4c0, 0xb6fadb98, 0xb6fb1050, 0xb6fad4c0, 0xb6fb1050)
      = -1 ENOSYS (Function not implemented)

This patch fixes the label so that we correctly dispatch private
syscalls from the trace path.

Reported-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent c89efa73

arch/arm/kernel/entry-common.S

+2 −2

Original line number	Diff line number	Diff line
		@@ -442,10 +442,10 @@ local_restart:
		ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine

		add r1, sp, #S_OFF
		cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
		2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
		eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
		bcs arm_syscall
		2: mov why, #0 @ no longer a real syscall
		mov why, #0 @ no longer a real syscall
		b sys_ni_syscall @ not private func

		#if defined(CONFIG_OABI_COMPAT) \|\| !defined(CONFIG_AEABI)