Jibin Xu 1c4d760039 sysrq : fix Show Regs call trace on ARM ... [ Upstream commit b00bebbc30 ] When kernel configuration SMP,PREEMPT and DEBUG_PREEMPT are enabled, echo 1 >/proc/sys/kernel/sysrq echo p >/proc/sysrq-trigger kernel will print call trace as below: sysrq: SysRq : Show Regs BUG: using __this_cpu_read() in preemptible [00000000] code: sh/435 caller is __this_cpu_preempt_check+0x18/0x20 Call trace: [<ffffff8008088e80>] dump_backtrace+0x0/0x1d0 [<ffffff8008089074>] show_stack+0x24/0x30 [<ffffff8008447970>] dump_stack+0x90/0xb0 [<ffffff8008463950>] check_preemption_disabled+0x100/0x108 [<ffffff8008463998>] __this_cpu_preempt_check+0x18/0x20 [<ffffff80084c9194>] sysrq_handle_showregs+0x1c/0x40 [<ffffff80084c9c7c>] __handle_sysrq+0x12c/0x1a0 [<ffffff80084ca140>] write_sysrq_trigger+0x60/0x70 [<ffffff8008251e00>] proc_reg_write+0x90/0xd0 [<ffffff80081f1788>] __vfs_write+0x48/0x90 [<ffffff80081f241c>] vfs_write+0xa4/0x190 [<ffffff80081f3354>] SyS_write+0x54/0xb0 [<ffffff80080833f0>] el0_svc_naked+0x24/0x28 This can be seen on a common board like an r-pi3. This happens because when echo p >/proc/sysrq-trigger, get_irq_regs() is called outside of IRQ context, if preemption is enabled in this situation,kernel will print the call trace. Since many prior discussions on the mailing lists have made it clear that get_irq_regs either just returns NULL or stale data when used outside of IRQ context,we simply avoid calling it outside of IRQ context. Signed-off-by: Jibin Xu <jibin.xu@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2017-12-09 18:42:40 +01:00
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hvc
ipwireless
serial	serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X	2017-12-09 18:42:40 +01:00
vt	vt: fix unchecked __put_user() in tioclinux ioctls	2017-07-21 07:44:57 +02:00
amiserial.c
bfin_jtag_comm.c
cyclades.c
ehv_bytechan.c
goldfish.c	Revert "tty: goldfish: Fix a parameter of a call to free_irq"	2017-10-21 17:09:06 +02:00
isicom.c
Kconfig
Makefile
metag_da.c
mips_ejtag_fdc.c
moxa.c
moxa.h
mxser.c
mxser.h
n_gsm.c
n_hdlc.c	tty: n_hdlc: get rid of racy n_hdlc.tbuf	2017-03-15 09:57:10 +08:00
n_r3964.c
n_tracerouter.c
n_tracesink.c
n_tracesink.h
n_tty.c
nozomi.c	tty: nozomi: avoid a harmless gcc warning	2017-04-30 05:49:27 +02:00
pty.c	tty: pty: Fix ldisc flush after userspace become aware of the data already	2017-05-20 14:27:02 +02:00
rocket_int.h
rocket.c
rocket.h
synclink_gt.c
synclink.c
synclinkmp.c
sysrq.c	sysrq : fix Show Regs call trace on ARM	2017-12-09 18:42:40 +01:00
tty_audit.c
tty_buffer.c	tty: fix __tty_insert_flip_char regression	2017-09-27 11:00:13 +02:00
tty_io.c	tty: Drop krefs for interrupted tty lock	2017-06-14 13:16:26 +02:00
tty_ioctl.c
tty_ldisc.c	tty: Prevent ldisc drivers from re-using stale tty fields	2016-11-21 10:06:40 +01:00
tty_ldsem.c
tty_mutex.c	tty: Drop krefs for interrupted tty lock	2017-06-14 13:16:26 +02:00
tty_port.c