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linux/arch/mips/kernel
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James Hogan 64bedffe49 MIPS: Clear [MSA]FPE CSR.Cause after notify_die() 
When handling floating point exceptions (FPEs) and MSA FPEs the Cause
bits of the appropriate control and status register (FCSR for FPEs and
MSACSR for MSA FPEs) are read and cleared before enabling interrupts,
presumably so that it doesn't have to go through the pain of restoring
those bits if the process is pre-empted, since writing those bits would
cause another immediate exception while still in the kernel.

The bits aren't normally ever restored again, since userland never
expects to see them set.

However for virtualisation it is necessary for the kernel to be able to
restore these Cause bits, as the guest may have been interrupted in an
FP exception handler but before it could read the Cause bits. This can
be done by registering a die notifier, to get notified of the exception
when such a value is restored, and if the PC was at the instruction
which is used to restore the guest state, the handler can step over it
and continue execution. The Cause bits can then remain set without
causing further exceptions.

For this to work safely a few changes are made:
- __build_clear_fpe and __build_clear_msa_fpe no longer clear the Cause
  bits, and now return from exception level with interrupts disabled
  instead of enabled.
- do_fpe() now clears the Cause bits and enables interrupts after
  notify_die() is called, so that the notifier can chose to return from
  exception without this happening.
- do_msa_fpe() acts similarly, but now actually makes use of the second
  argument (msacsr) and calls notify_die() with the new DIE_MSAFP,
  allowing die notifiers to be informed of MSA FPEs too.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
2015-03-27 21:25:06 +00:00
..
.gitignore
8250-platform.c
asm-offsets.c Revert "MIPS: Don't assume 64-bit FP registers for context switch" 2015-03-27 19:42:48 +01:00
binfmt_elfn32.c
binfmt_elfo32.c MIPS: Remove old core dump functions 2014-08-02 00:06:37 +02:00
bmips_vec.S MIPS: BMIPS: Fix ".previous without corresponding .section" warnings 2014-11-24 07:44:05 +01:00
branch.c MIPS: kernel: mips-r2-to-r6-emul: Add R2 emulator for MIPS R6 2015-02-17 15:37:37 +00:00
cevt-bcm1480.c
cevt-ds1287.c
cevt-gt641xx.c
cevt-r4k.c MIPS: kernel: cevt-r4k: Add MIPS R6 to the c0_compare_interrupt handler 2015-02-17 15:37:25 +00:00
cevt-sb1250.c
cevt-txx9.c
cps-vec.S MIPS: kernel: cps-vec: Replace "addi" with "addiu" 2015-02-17 15:37:28 +00:00
cpu-bugs64.c MIPS: kernel: cpu-bugs64: Do not check R6 cores for existing 64-bit bugs 2015-02-17 15:37:24 +00:00
cpu-probe.c MIPS: Add set/clear CP0 macros for PageGrain register 2015-02-20 12:55:18 +01:00
crash_dump.c mips: Convert pr_warning to pr_warn 2014-11-24 07:44:51 +01:00
crash.c mips: delete non-required instances of include <linux/init.h> 2014-01-24 22:39:56 +01:00
csrc-bcm1480.c
csrc-ioasic.c MIPS: DECstation HRT initialization rearrangement 2013-09-13 11:56:13 +02:00
csrc-r4k.c
csrc-sb1250.c
early_printk_8250.c MIPS: Add 8250/16550 serial early printk driver 2013-10-29 21:24:36 +01:00
early_printk.c
elf.c MIPS: kernel: elf: Improve the overall ABI and FPU mode checks 2015-02-17 15:37:39 +00:00
entry.S MIPS: Make use of the ERETNC instruction on MIPS R6 2015-02-17 15:37:37 +00:00
ftrace.c Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2014-08-07 08:47:00 -07:00
genex.S MIPS: Clear [MSA]FPE CSR.Cause after notify_die() 2015-03-27 21:25:06 +00:00
gpio_txx9.c
head.S MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
i8253.c
i8259.c MIPS: i8259: Use IRQ domains 2014-11-24 07:44:52 +01:00
idle.c MIPS: Add cases for CPU_QEMU_GENERIC 2015-02-16 10:01:24 +00:00
irq_cpu.c MIPS: IRQ: Fix disable_irq on CPU IRQs 2015-01-16 14:03:17 +01:00
irq_txx9.c
irq-gt641xx.c
irq-msc01.c MIPS: MSC: Prevent out-of-bounds writes to MIPS SC ioremap'd region 2014-06-26 10:48:23 +01:00
irq-rm7000.c
irq.c Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2014-06-09 18:10:34 -07:00
jump_label.c MIPS: jump_label.c: Handle the microMIPS J instruction encoding 2014-11-19 18:22:09 +01:00
kgdb.c MIPS: kernel: {ftrace,kgdb}: Set correct address limit for cache flushes 2014-03-26 23:09:18 +01:00
kprobes.c mips: Replace __get_cpu_var uses 2014-08-26 13:45:51 -04:00
linux32.c
machine_kexec.c MIPS: kdump: Set correct value to kexec_indirection_page variable 2014-08-25 16:33:44 +02:00
Makefile MIPS: kernel: mips-r2-to-r6-emul: Add R2 emulator for MIPS R6 2015-02-17 15:37:37 +00:00
mcount.S MIPS: mcount: Adjust stack pointer for static trace in MIPS32 2014-09-26 11:41:17 +02:00
mips_ksyms.c Merge branch 'mipsr6-for-3.20' of git://git.linux-mips.org/pub/scm/mchandras/linux into mips-for-linux-next 2015-02-19 16:00:34 +01:00
mips_machine.c
mips-cm.c MIPS: Replace use of phys_t with phys_addr_t. 2014-11-24 22:47:31 +01:00
mips-cpc.c MIPS: Replace use of phys_t with phys_addr_t. 2014-11-24 22:47:31 +01:00
mips-mt-fpaff.c MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
mips-mt.c MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
mips-r2-to-r6-emul.c MIPS: kernel: mips-r2-to-r6-emul: Add R2 emulator for MIPS R6 2015-02-17 15:37:37 +00:00
module-rela.c
module.c mm: vmalloc: pass additional vm_flags to __vmalloc_node_range() 2015-02-13 21:21:42 -08:00
octeon_switch.S MIPS: OCTEON: Delete unused COP2 saving code 2015-02-20 15:30:23 +01:00
perf_event_mipsxx.c MIPS: Add hook to get C0 performance counter interrupt 2014-11-24 07:44:53 +01:00
perf_event.c
pm-cps.c MIPS: {pm,smp}-cps: use cpu_vpe_id macro 2014-07-30 20:48:42 +02:00
pm.c MIPS: PM: Implement PM helper macros 2014-05-02 16:39:10 +01:00
proc.c MIPS: kernel: proc: Add MIPS R6 support to /proc/cpuinfo 2015-02-17 15:37:26 +00:00
process.c Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2015-02-21 19:41:38 -08:00
prom.c MIPS: Create a helper function for DT setup 2014-11-24 07:45:12 +01:00
ptrace32.c MIPS: Remove asm/user.h 2014-08-02 00:06:37 +02:00
ptrace.c MIPS: prevent FP context set via ptrace being discarded 2015-03-27 19:42:47 +01:00
r4k_fpu.S MIPS: Push .set mips64r* into the functions needing it 2015-03-27 19:42:42 +01:00
r4k_switch.S MIPS: kernel: r4k_switch: Add support for MIPS R6 2015-02-17 15:37:27 +00:00
r2300_fpu.S MIPS: Fix build with binutils 2.24.51+ 2014-11-07 15:07:36 +01:00
r2300_switch.S MIPS: Fix build with binutils 2.24.51+ 2014-11-07 15:07:36 +01:00
r6000_fpu.S MIPS: Fix build with binutils 2.24.51+ 2014-11-07 15:07:36 +01:00
relocate_kernel.S MIPS: kdump: Skip walking indirection page for crashkernels 2013-09-05 20:53:37 +02:00
reset.c
rtlx-cmp.c MIPS: APRP: Fix an issue when device_create() fails. 2014-08-01 17:30:35 +02:00
rtlx-mt.c MIPS: APRP: Fix an issue when device_create() fails. 2014-08-01 17:30:35 +02:00
rtlx.c MIPS: rtlx: Remove KERN_DEBUG from pr_debug() arguments in rtlx.c 2014-11-24 07:44:04 +01:00
scall32-o32.S MIPS: Fix restart of indirect syscalls 2015-01-16 00:35:45 +01:00
scall64-64.S MIPS: Wire up execveat(2). 2015-01-13 15:53:09 +01:00
scall64-n32.S MIPS: Wire up execveat(2). 2015-01-13 15:53:09 +01:00
scall64-o32.S MIPS: Fix restart of indirect syscalls 2015-01-16 00:35:45 +01:00
segment.c MIPS: Add debugfs file to print the segmentation control registers 2014-01-22 20:19:00 +01:00
setup.c MIPS: Use phys_addr_t instead of phys_t 2014-12-12 15:36:13 -08:00
signal32.c all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
signal_n32.c mips: Use sigsp() 2014-08-06 13:04:30 +02:00
signal-common.h mips: Use get_signal() signal_setup_done() 2014-08-06 13:03:08 +02:00
signal.c all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
smp-bmips.c MIPS: BMIPS: Let each platform customize the CPU1 IRQ mask 2014-11-24 07:45:11 +01:00
smp-cmp.c MIPS: smp-mt,smp-cmp: Enable all HW IRQs on secondary CPUs 2015-01-16 13:02:40 +01:00
smp-cps.c MIPS: Move gic.h to include/linux/irqchip/mips-gic.h 2014-11-24 07:44:59 +01:00
smp-gic.c MIPS: Move gic.h to include/linux/irqchip/mips-gic.h 2014-11-24 07:44:59 +01:00
smp-mt.c MIPS: smp-mt,smp-cmp: Enable all HW IRQs on secondary CPUs 2015-01-16 13:02:40 +01:00
smp-up.c MIPS: SMP: Remove plat_smp_ops cpus_done method. 2014-05-27 11:06:42 +02:00
smp.c MIPS: Fix kernel lockup or crash after CPU offline/online 2015-01-29 23:54:07 +01:00
spinlock_test.c
spram.c MIPS: Add cases for CPU_QEMU_GENERIC 2015-02-16 10:01:24 +00:00
stacktrace.c
sync-r4k.c MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
syscall.c MIPS: kernel: syscall: Set the appropriate ISA level for MIPS R6 2015-02-17 15:37:29 +00:00
time.c MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
topology.c
traps.c MIPS: Clear [MSA]FPE CSR.Cause after notify_die() 2015-03-27 21:25:06 +00:00
unaligned.c MIPS: kernel: unaligned: Add support for the MIPS R6 2015-02-17 15:37:28 +00:00
vdso.c MIPS: Enable VDSO randomization 2014-11-24 07:45:38 +01:00
vmlinux.lds.S MIPS: Discard .eh_frame sections in linker script. 2013-08-26 15:33:41 +02:00
vpe-cmp.c MIPS: APRP: Add VPE loader support for CMP platforms. 2014-01-22 20:19:02 +01:00
vpe-mt.c MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
vpe.c Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2014-01-30 17:20:32 -08:00
watch.c