linux/arch/openrisc
Stafford Horne ae15a41a64 openrisc: entry: Fix delay slot exception detection
Originally in patch e6d20c55a4 ("openrisc: entry: Fix delay slot
detection") I fixed delay slot detection, but only for QEMU.  We missed
that hardware delay slot detection using delay slot exception flag (DSX)
was still broken.  This was because QEMU set the DSX flag in both
pre-exception supervision register (ESR) and supervision register (SR)
register, but on real hardware the DSX flag is only set on the SR
register during exceptions.

Fix this by carrying the DSX flag into the SR register during exception.
We also update the DSX flag read locations to read the value from the SR
register not the pt_regs SR register which represents ESR.  The ESR
should never have the DSX flag set.

In the process I updated/removed a few comments to match the current
state.  Including removing a comment saying that the DSX detection logic
was inefficient and needed to be rewritten.

I have tested this on QEMU with a patch ensuring it matches the hardware
specification.

Link: https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg00000.html
Fixes: e6d20c55a4 ("openrisc: entry: Fix delay slot detection")
Signed-off-by: Stafford Horne <shorne@gmail.com>
2018-07-01 16:48:24 +09:00
..
boot/dts DeviceTree for 4.15: 2017-11-14 18:25:40 -08:00
configs openrisc: add simple_smp dts and defconfig for simulators 2017-11-03 14:01:15 +09:00
include openrisc: Call destructor during __pte_free_tlb 2018-06-25 21:49:10 +09:00
kernel openrisc: entry: Fix delay slot exception detection 2018-07-01 16:48:24 +09:00
lib OpenRISC updates for v4.15 2017-11-13 12:12:00 -08:00
mm signal/openrisc: Use force_sig_fault where appropriate 2018-04-25 10:44:05 -05:00
Kconfig openrisc: Set CONFIG_MULTI_IRQ_HANDLER 2018-04-04 12:04:28 +02:00
Makefile kbuild: add endianness flag to CHEKCFLAGS 2018-05-29 22:05:08 +09:00