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linux/arch/powerpc/kernel
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Michael Ellerman 0828137e8f powerpc/64s: Don't init FSCR_DSCR in __init_FSCR() 
__init_FSCR() was added originally in commit 2468dcf641 ("powerpc:
Add support for context switching the TAR register") (Feb 2013), and
only set FSCR_TAR.

At that point FSCR (Facility Status and Control Register) was not
context switched, so the setting was permanent after boot.

Later we added initialisation of FSCR_DSCR to __init_FSCR(), in commit
54c9b2253d ("powerpc: Set DSCR bit in FSCR setup") (Mar 2013), again
that was permanent after boot.

Then commit 2517617e0d ("powerpc: Fix context switch DSCR on
POWER8") (Aug 2013) added a limited context switch of FSCR, just the
FSCR_DSCR bit was context switched based on thread.dscr_inherit. That
commit said "This clears the H/FSCR DSCR bit initially", but it
didn't, it left the initialisation of FSCR_DSCR in __init_FSCR().
However the initial context switch from init_task to pid 1 would clear
FSCR_DSCR because thread.dscr_inherit was 0.

That commit also introduced the requirement that FSCR_DSCR be clear
for user processes, so that we can take the facility unavailable
interrupt in order to manage dscr_inherit.

Then in commit 152d523e63 ("powerpc: Create context switch helpers
save_sprs() and restore_sprs()") (Dec 2015) FSCR was added to
thread_struct. However it still wasn't fully context switched, we just
took the existing value and set FSCR_DSCR if the new thread had
dscr_inherit set. FSCR was still initialised at boot to FSCR_DSCR |
FSCR_TAR, but that value was not propagated into the thread_struct, so
the initial context switch set FSCR_DSCR back to 0.

Finally commit b57bd2de8c ("powerpc: Improve FSCR init and context
switching") (Jun 2016) added a full context switch of the FSCR, and
added an initialisation of init_task.thread.fscr to FSCR_TAR |
FSCR_EBB, but omitted FSCR_DSCR.

The end result is that swapper runs with FSCR_DSCR set because of the
initialisation in __init_FSCR(), but no other processes do, they use
the value from init_task.thread.fscr.

Having FSCR_DSCR set for swapper allows it to access SPR 3 from
userspace, but swapper never runs userspace, so it has no useful
effect. It's also confusing to have the value initialised in two
places to two different values.

So remove FSCR_DSCR from __init_FSCR(), this at least gets us to the
point where there's a single value of FSCR, even if it's still set in
two places.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200527145843.2761782-1-mpe@ellerman.id.au
2020-06-02 20:59:17 +10:00
..
ptrace powerpc/watchpoint: Use builtin ALIGN*() macros 2020-05-19 00:11:05 +10:00
syscalls asm-generic: fix unistd_32.h generation format 2020-04-07 10:43:42 -07:00
trace powerpc: Add a probe_kernel_read_inst() function 2020-05-19 00:10:37 +10:00
vdso32 powerpc/vdso32: Fallback on getres syscall when clock is unknown 2020-05-11 19:24:29 +10:00
vdso64 .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
align.c powerpc: Define and use get_user_instr() et. al. 2020-05-19 00:10:37 +10:00
asm-offsets.c powerpc/xmon: Move breakpoints to text section 2020-05-19 00:10:36 +10:00
audit.c
btext.c powerpc: Prefer __section and __printf from compiler_attributes.h 2020-03-27 00:16:32 +11:00
cacheinfo.c
cacheinfo.h
compat_audit.c
cpu_setup_6xx.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
cpu_setup_44x.S
cpu_setup_fsl_booke.S powerpc/booke: Spelling s/date/data/ 2019-11-17 01:56:31 -06:00
cpu_setup_pa6t.S
cpu_setup_power.S powerpc/64s: Don't init FSCR_DSCR in __init_FSCR() 2020-06-02 20:59:17 +10:00
cpu_setup_ppc970.S
cputable.c powerpc/40x: Remove support for IBM 405GP 2020-05-28 23:24:36 +10:00
crash_dump.c powerpc: Add prefixed instructions to instruction data type 2020-05-19 00:10:39 +10:00
dawr.c powerpc/watchpoint: Disable all available watchpoints when !dawr_force_enable 2020-05-19 00:11:05 +10:00
dbell.c KVM: PPC: Book3S HV: use smp_mb() when setting/clearing host_ipi flag 2019-09-24 12:46:26 +10:00
dma-iommu.c powerpc updates for 5.4 2019-09-20 11:48:06 -07:00
dma-mask.c
dma-swiotlb.c
dt_cpu_ftrs.c powerpc/64: Setup a paca before parsing device tree etc. 2020-03-25 12:09:37 +11:00
early_32.c powerpc/fsl_booke/32: implement KASLR infrastructure 2019-11-13 19:27:40 +11:00
eeh.c powerpc/eeh: Release EEH device state synchronously 2020-05-18 21:58:44 +10:00
eeh_cache.c powerpc/eeh_cache: Don't use pci_dn when inserting new ranges 2020-01-23 21:31:18 +11:00
eeh_dev.c powerpc/eeh: Add bdfn field to eeh_dev 2019-08-22 23:12:46 +10:00
eeh_driver.c powerpc/eeh: Fix deadlock handling dead PHB 2020-02-17 12:47:05 +11:00
eeh_event.c powerpc/eeh: Fix build with STACKTRACE=n 2019-09-14 00:01:14 +10:00
eeh_pe.c powerpc/eeh: Clean up EEH PEs after recovery finishes 2019-09-05 14:22:37 +10:00
eeh_sysfs.c powerpc/eeh_sysfs: Make clearing EEH_DEV_SYSFS saner 2020-01-23 21:31:19 +11:00
entry_32.S powerpc/entry32: Blacklist exception exit points for kprobe. 2020-06-02 20:59:13 +10:00
entry_64.S powerpc/64s/kuap: Conditionally restore AMR in kuap_restore_amr asm 2020-05-28 23:24:37 +10:00
epapr_hcalls.S
epapr_paravirt.c powerpc: Use a datatype for instructions 2020-05-19 00:10:37 +10:00
exceptions-64e.S powerpc/64s: Implement interrupt exit logic in C 2020-04-01 13:42:14 +11:00
exceptions-64s.S powerpc/64s/kuap: Conditionally restore AMR in kuap_restore_amr asm 2020-05-28 23:24:37 +10:00
fadump.c powerpc/fadump: Account for memory_limit while reserving memory 2020-06-02 20:59:05 +10:00
firmware.c
fpu.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
fsl_booke_entry_mapping.S powerpc/fsl_booke/32: implement KASLR infrastructure 2019-11-13 19:27:40 +11:00
head_8xx.S powerpc/8xx: Map linear memory with huge pages 2020-05-26 22:22:23 +10:00
head_32.h Merge branch 'fixes' into next 2020-03-10 15:16:42 +11:00
head_32.S powerpc/rtas: Remove machine_check_in_rtas() 2020-06-02 20:59:11 +10:00
head_40x.S powerpc/40x: Don't save CR in SPRN_SPRG_SCRATCH6 2020-05-28 23:24:36 +10:00
head_44x.S
head_64.S powerpc/64: Don't initialise init_task->thread.regs 2020-05-15 11:58:54 +10:00
head_booke.h powerpc: Replace _ALIGN_UP() by ALIGN() 2020-05-11 23:15:15 +10:00
head_fsl_booke.S powerpc/32: save DEAR/DAR before calling handle_page_fault 2020-01-26 22:15:09 +11:00
hw_breakpoint.c powerpc/watchpoint: Don't allow concurrent perf and ptrace events 2020-05-19 00:14:45 +10:00
idle.c powerpc/64s: Reimplement power4_idle code in C 2020-01-16 14:59:37 +10:00
idle_6xx.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
idle_book3e.S
idle_book3s.S powerpc/64s: Reimplement power4_idle code in C 2020-01-16 14:59:37 +10:00
idle_e500.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
ima_arch.c powerpc/ima: Fix secure boot rules in ima arch policy 2020-05-07 17:25:54 +10:00
io-workarounds.c powerpc/mm: rework io-workaround invocation. 2019-08-27 13:03:34 +10:00
io.c
iomap.c
iommu.c Merge branch 'topic/ppc-kvm' into next 2019-08-30 09:52:57 +10:00
irq.c powerpc/64s: Fix doorbell wakeup msgclr optimisation 2020-04-03 00:09:53 +11:00
isa-bridge.c
jump_label.c powerpc: Use a datatype for instructions 2020-05-19 00:10:37 +10:00
kgdb.c powerpc: Use a datatype for instructions 2020-05-19 00:10:37 +10:00
kprobes-ftrace.c
kprobes.c powerpc/kprobes: Use probe_address() to read instructions 2020-06-02 20:59:08 +10:00
kvm.c powerpc/kvm: Explicitly mark kvm guest code as __init 2019-09-14 00:04:40 +10:00
kvm_emul.S powerpc/kvm: Add ifdefs around template code 2019-09-14 00:04:40 +10:00
l2cr_6xx.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
legacy_serial.c tty/serial: Migrate 8250_fsl to use has_sysrq 2019-12-18 15:04:42 +01:00
Makefile powerpc/64: make buildable without CONFIG_COMPAT 2020-04-03 00:10:00 +11:00
mce.c powerpc/64s: machine check do not trace real-mode handler 2020-05-19 00:10:34 +10:00
mce_power.c powerpc: Use a function for reading instructions 2020-05-19 00:10:37 +10:00
misc.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
misc_32.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
misc_64.S Merge branch 'topic/kaslr-book3e32' into next 2019-11-14 19:23:33 +11:00
module.c
module.lds
module_32.c powerpc: module_[32|64].c: replace swap function with built-in one 2020-05-11 23:15:14 +10:00
module_64.c powerpc/module_64: Use special stub for _mcount() with -mprofile-kernel 2020-06-02 20:59:16 +10:00
msi.c
note.S powerpc: Add PowerPC Capabilities ELF note 2019-08-30 09:40:15 +10:00
nvram_64.c powerpc: Replace _ALIGN_UP() by ALIGN() 2020-05-11 23:15:15 +10:00
of_platform.c powerpc/eeh: Make early EEH init pseries specific 2020-03-25 12:09:39 +11:00
optprobes.c powerpc: Add ppc_inst_as_u64() 2020-05-26 23:36:57 +10:00
optprobes_head.S powerpc: Add prefixed instructions to instruction data type 2020-05-19 00:10:39 +10:00
paca.c powerpc/rtas: Implement reentrant rtas call 2020-06-02 20:59:08 +10:00
pci-common.c powerpc updates for 5.7 2020-04-05 11:12:59 -07:00
pci-hotplug.c powerpc/eeh: Release EEH device state synchronously 2020-05-18 21:58:44 +10:00
pci_32.c
pci_64.c powerpc: Replace _ALIGN_UP() by ALIGN() 2020-05-11 23:15:15 +10:00
pci_dn.c powerpc/pcidn: Warn when sriov pci_dn management is used incorrectly 2020-01-23 21:31:19 +11:00
pci_of_scan.c powerpc/pci: Remove pcibios_setup_bus_devices() 2020-01-06 16:25:29 +11:00
pmc.c
ppc32.h
ppc_save_regs.S powerpc: Improve ppc_save_regs() 2020-04-04 21:40:57 +11:00
proc_powerpc.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
process.c powerpc/watchpoint: Prepare handler to handle more than one watchpoint 2020-05-19 00:14:37 +10:00
prom.c powerpc/kernel: Enables memory hot-remove after reboot on pseries guests 2020-06-02 20:59:07 +10:00
prom_init.c powerpc: Replace _ALIGN() by ALIGN() 2020-05-11 23:15:16 +10:00
prom_init_check.sh powerpc/prom_init: Undo relocation before entering secure mode 2019-10-29 15:12:17 +11:00
prom_parse.c
reloc_32.S
reloc_64.S
rtas-proc.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
rtas-rtc.c
rtas.c powerpc/rtas: Implement reentrant rtas call 2020-06-02 20:59:08 +10:00
rtas_flash.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
rtas_pci.c
rtasd.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
secure_boot.c powerpc: Detect the trusted boot state of the system 2019-11-12 12:25:49 +11:00
security.c powerpc: Use a macro for creating instructions from u32s 2020-05-19 00:10:36 +10:00
secvar-ops.c powerpc/powernv: Add OPAL API interface to access secure variable 2019-11-13 00:33:22 +11:00
secvar-sysfs.c powerpc: expose secure variables to userspace via sysfs 2019-11-13 00:33:22 +11:00
setup-common.c powerpc/40x: Remove support for IBM 403GCX 2020-05-28 23:24:35 +10:00
setup.h powerpc/64: Prevent stack protection in early boot 2020-03-25 12:09:38 +11:00
setup_32.c powerpc/mm: Allocate static page tables for fixmap 2020-05-26 22:22:19 +10:00
setup_64.c Merge branch 'fixes' into next 2020-05-26 22:56:03 +10:00
signal.c powerpc/watchpoint: Convert thread_struct->hw_brk to an array 2020-05-19 00:11:05 +10:00
signal.h powerpc/64/sycall: Implement syscall entry/exit logic in C 2020-04-01 13:42:13 +11:00
signal_32.c powerpc: Use trap metadata to prevent double restart rather than zeroing trap 2020-05-15 11:58:54 +10:00
signal_64.c powerpc: Use trap metadata to prevent double restart rather than zeroing trap 2020-05-15 11:58:54 +10:00
smp-tbsync.c
smp.c powerpc: Fix misleading small cores print 2020-06-02 20:59:06 +10:00
stacktrace.c powerpc: Rename current_stack_pointer() to current_stack_frame() 2020-03-04 22:44:28 +11:00
suspend.c
swsusp.c
swsusp_32.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
swsusp_64.c
swsusp_asm64.S
swsusp_booke.S
sys_ppc32.c
syscall_64.c powerpc/64/kuap: Conditionally restore AMR in interrupt exit 2020-05-28 23:24:37 +10:00
syscalls.c y2038: syscalls: change remaining timeval to __kernel_old_timeval 2019-11-15 14:38:29 +01:00
sysfs.c powerpc/sysfs: Show idle_purr and idle_spurr for every CPU 2020-04-30 12:35:26 +10:00
systbl.S powerpc/64/sycall: Implement syscall entry/exit logic in C 2020-04-01 13:42:13 +11:00
systbl_chk.sh
tau_6xx.c
time.c Revert "powerpc/64: irq_work avoid interrupt when called with hardware irqs enabled" 2020-04-03 16:55:34 +11:00
tm.S
traps.c powerpc: Support prefixed instructions in alignment handler 2020-05-19 00:11:03 +10:00
ucall.S powerpc/kernel: Add ucall_norets() ultravisor call handler 2019-08-30 09:40:15 +10:00
udbg.c powerpc/udbg: Make it safe to call udbg_printf() always 2019-10-11 19:33:25 +11:00
udbg_16550.c
uprobes.c powerpc: Add ppc_inst_next() 2020-05-26 23:36:51 +10:00
vdso.c powerpc/64: make buildable without CONFIG_COMPAT 2020-04-03 00:10:00 +11:00
vecemu.c powerpc: Define and use get_user_instr() et. al. 2020-05-19 00:10:37 +10:00
vector.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
vmlinux.lds.S powerpc/mm: Don't be too strict with _etext alignment on PPC32 2020-05-26 22:22:22 +10:00
watchdog.c