linux/arch/arm64/include/asm
Ard Biesheuvel 34be98f494 arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP
For historical reasons, we leave the top 16 bytes of our task and IRQ
stacks unused, a practice used to ensure that the SP can always be
masked to find the base of the current stack (historically, where
thread_info could be found).

However, this is not necessary, as:

* When an exception is taken from a task stack, we decrement the SP by
  S_FRAME_SIZE and stash the exception registers before we compare the
  SP against the task stack. In such cases, the SP must be at least
  S_FRAME_SIZE below the limit, and can be safely masked to determine
  whether the task stack is in use.

* When transitioning to an IRQ stack, we'll place a dummy frame onto the
  IRQ stack before enabling asynchronous exceptions, or executing code
  we expect to trigger faults. Thus, if an exception is taken from the
  IRQ stack, the SP must be at least 16 bytes below the limit.

* We no longer mask the SP to find the thread_info, which is now found
  via sp_el0. Note that historically, the offset was critical to ensure
  that cpu_switch_to() found the correct stack for new threads that
  hadn't yet executed ret_from_fork().

Given that, this initial offset serves no purpose, and can be removed.
This brings us in-line with other architectures (e.g. x86) which do not
rely on this masking.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[Mark: rebase, kill THREAD_START_SP, commit msg additions]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
2017-08-15 18:34:53 +01:00
..
xen arm/arm64: xen: Move shared architecture headers to include/xen/arm 2016-12-02 11:49:55 -08:00
acenv.h ARM64 / ACPI: Get RSDP and ACPI boot-time tables 2015-03-25 11:49:30 +00:00
acpi.h ARM64/ACPI: Fix BAD_MADT_GICC_ENTRY() macro implementation 2017-06-02 15:13:52 +01:00
alternative.h arm64: Fix circular include of asm/lse.h through linux/jump_label.h 2016-11-05 20:59:06 +00:00
arch_gicv3.h arm64/kvm: sysreg: fix typo'd SYS_ICC_IGRPEN*_EL1 2017-06-15 09:45:07 +01:00
arch_timer.h arm64: arch_timer: Allow erratum matching with ACPI OEM information 2017-04-07 11:22:10 +01:00
arm-cci.h arm-cci: Get rid of secure transactions for PMU driver 2015-03-27 13:44:35 +00:00
asm-bug.h arm64: Add ASM_BUG() 2017-08-08 16:28:13 +01:00
asm-offsets.h
asm-uaccess.h arm64: entry: improve data abort handling of tagged pointers 2017-05-09 17:26:59 +01:00
assembler.h arm64: move non-entry code out of .entry.text 2017-08-08 16:28:25 +01:00
atomic_ll_sc.h arm64: Remove redundant mov from LL/SC cmpxchg 2017-05-15 18:30:10 +01:00
atomic_lse.h arm64: atomics: Remove '&' from '+&' asm constraint in lse atomics 2017-07-20 10:20:54 +01:00
atomic.h locking/atomic: Remove linux/atomic.h:atomic_fetch_or() 2016-06-16 10:48:32 +02:00
barrier.h arm64: ensure extension of smp_store_release value 2017-05-09 17:45:04 +01:00
bitops.h
bitrev.h ARM: 8189/1: arm64:add bitrev.h file to support rbit instruction 2014-12-22 16:47:32 +00:00
boot.h arm64: allow kernel Image to be loaded anywhere in physical memory 2016-02-18 18:16:53 +00:00
brk-imm.h arm64: move brk immediate argument definitions to separate header 2016-02-23 17:43:25 +00:00
bug.h arm64: Add ASM_BUG() 2017-08-08 16:28:13 +01:00
cache.h arm64: cache: Identify VPIPT I-caches 2017-03-20 16:17:02 +00:00
cacheflush.h treewide: decouple cacheflush.h and set_memory.h 2017-05-08 17:15:14 -07:00
checksum.h arm64: add missing conversion to __wsum in ip_fast_csum() 2017-06-29 16:32:43 +01:00
clocksource.h arm/arm64: arch_timer: Use archdata to indicate vdso suitability 2016-09-23 17:19:25 +01:00
cmpxchg.h arm64: xchg: hazard against entire exchange variable 2017-05-09 17:44:50 +01:00
compat.h sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
compiler.h
cpu_ops.h ARM64: kernel: unify ACPI and DT cpus initialization 2015-05-19 16:09:29 +01:00
cpu.h arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to sysfs 2016-07-12 16:09:37 +01:00
cpucaps.h arm64: Add workaround for Cavium Thunder erratum 30115 2017-06-15 09:45:04 +01:00
cpufeature.h arm64/cpufeature: don't use mutex in bringup path 2017-05-17 17:00:29 +01:00
cpuidle.h arm64: kernel: rename __cpu_suspend to keep it aligned with arm 2015-06-19 14:46:39 +01:00
cputype.h arm64: Add MIDR values for Cavium cn83XX SoCs 2017-06-15 09:45:04 +01:00
current.h arm64: remove redundant header file in current.h 2017-03-30 19:15:37 +01:00
dcc.h arm64: dcc: simplify accessors 2016-09-09 11:41:13 +01:00
debug-monitors.h arm64: Add uprobe support 2016-11-07 18:15:21 +00:00
device.h xen/arm,arm64: fix xen_dma_ops after 815dd18 "Consolidate get_dma_ops..." 2017-05-02 11:14:42 +02:00
dma-mapping.h This is the first pull request for the new dma-mapping subsystem 2017-07-06 19:20:54 -07:00
dmi.h arm64: dmi: Add SMBIOS/DMI support 2014-11-05 09:03:25 +01:00
efi.h efi/arm-stub: Round up FDT allocation to mapping size 2017-04-05 12:27:24 +02:00
elf.h arm64: move ELF_ET_DYN_BASE to 4GB / 4MB 2017-07-10 16:32:36 -07:00
esr.h PPC: 2017-07-06 18:38:31 -07:00
exception.h arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections 2016-03-25 16:37:42 -07:00
exec.h arm64: suspend: Reconfigure PSTATE after resume from idle 2016-10-20 09:50:54 +01:00
extable.h arm64: add extable.h 2017-03-28 18:23:23 -04:00
fb.h
fixmap.h arm64: Remove fixmap include fragility 2016-02-26 15:22:53 +00:00
fpsimd.h
fpsimdmacros.h arm64: Avoid breakage caused by .altmacro in fpsimd save/restore macros 2015-01-29 17:24:39 +00:00
ftrace.h arm64: Fix misspellings in comments. 2016-03-04 18:19:17 +00:00
futex.h arm64: futex: Fix undefined behaviour with FUTEX_OP_OPARG_SHIFT usage 2017-05-30 11:07:42 +01:00
hardirq.h arm64: kdump: implement machine_crash_shutdown() 2017-04-05 18:29:15 +01:00
hugetlb.h mm/hugetlb: clean up ARCH_HAS_GIGANTIC_PAGE 2017-07-06 16:24:33 -07:00
hw_breakpoint.h arm64: cpufeature: Make ID reg accessor naming less counterintuitive 2017-04-04 16:55:41 +01:00
hwcap.h arm64/HWCAP: Use system wide safe values 2015-10-21 15:35:58 +01:00
hypervisor.h
insn.h arm64: Prevent cpu hotplug rwsem recursion 2017-05-26 10:10:45 +02:00
io.h ARM64: Implement pci_remap_cfgspace() interface 2017-04-24 13:53:13 -05:00
irq_work.h arm64: force CONFIG_SMP=y and remove redundant #ifdefs 2015-07-27 11:08:40 +01:00
irq.h arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP 2017-08-15 18:34:53 +01:00
irqflags.h arm64: debug: remove unused local_dbg_{enable, disable} macros 2016-07-19 16:59:40 +01:00
jump_label.h locking/static_keys: Add a new static_key interface 2015-08-03 11:34:15 +02:00
kasan.h arm64: move kernel image to base of vmalloc area 2016-02-18 18:16:44 +00:00
Kbuild arm64: move generic-y of exported headers to uapi/asm/Kbuild 2017-07-10 03:43:20 +09:00
kernel-pgtable.h arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1 2016-11-21 18:48:53 +00:00
kexec.h arm64: kdump: implement machine_crash_shutdown() 2017-04-05 18:29:15 +01:00
kgdb.h arm64: kgdb: Match pstate size with gdbserver protocol 2016-06-16 19:20:51 +01:00
kprobes.h kprobes: move kprobe declarations to asm-generic/kprobes.h 2017-02-27 18:43:45 -08:00
kvm_arm.h arm/arm64: KVM: add guest SEA support 2017-06-22 18:22:05 +01:00
kvm_asm.h arm64: KVM: Convert __cpu_reset_hyp_mode to using __hyp_reset_vectors 2017-04-09 07:49:22 -07:00
kvm_coproc.h arm64: KVM: common infrastructure for handling AArch32 CP14/CP15 2014-07-11 04:57:44 -07:00
kvm_emulate.h arm64: KVM: Fix decoding of Rt/Rt2 when trapping AArch32 CP accesses 2017-05-02 09:53:46 +02:00
kvm_host.h KVM/ARM updates for 4.13 2017-06-30 12:38:26 +02:00
kvm_hyp.h KVM: arm64: vgic-v3: Add hook to handle guest GICv3 sysreg accesses at EL2 2017-06-15 09:44:59 +01:00
kvm_mmio.h KVM: arm/arm64: Export mmio_read/write_bus 2016-05-20 15:39:42 +02:00
kvm_mmu.h * ARM: HYP mode stub supports kexec/kdump on 32-bit; improved PMU 2017-05-08 12:37:56 -07:00
kvm_psci.h
linkage.h
lse.h arm64: do not trace atomic operations 2017-02-06 19:00:23 +00:00
memblock.h
memory.h arm64 updates for 4.11: 2017-02-22 10:46:44 -08:00
mmu_context.h sched/headers: Prepare to remove the <linux/mm_types.h> dependency from <linux/sched.h> 2017-03-02 08:42:37 +01:00
mmu.h arm64: alternatives: apply boot time fixups via the linear mapping 2017-03-23 13:54:19 +00:00
mmzone.h arm64, numa: Add NUMA support for arm64 platforms. 2016-04-15 18:06:09 +01:00
module.h arm64: ftrace: add support for far branches to dynamic ftrace 2017-06-07 11:52:02 +01:00
neon.h arm64: Support systems without FP/ASIMD 2016-11-16 18:05:10 +00:00
numa.h ACPI/NUMA: Do not map pxm to node when NUMA is turned off 2016-12-15 11:32:32 +01:00
page.h arm64: move {PAGE,CONT}_SHIFT into Kconfig 2016-06-03 10:57:18 +01:00
paravirt.h arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops 2015-12-21 14:40:54 +00:00
pci.h PCI: Add pci_mmap_resource_range() and use it for ARM64 2017-04-20 08:47:47 -05:00
percpu.h arm64: factor out current_stack_pointer 2016-11-11 18:25:43 +00:00
perf_event.h arm64 updates for 4.10: 2016-12-13 16:39:21 -08:00
pgalloc.h arm64: get rid of superfluous __GFP_REPEAT 2016-06-24 17:23:52 -07:00
pgtable-hwdef.h arm64: simplify sysreg manipulation 2016-09-09 11:43:50 +01:00
pgtable-prot.h arm64: Introduce execute-only page access permissions 2016-08-25 18:00:29 +01:00
pgtable-types.h arch, mm: convert all architectures to use 5level-fixup.h 2017-03-09 11:48:47 -08:00
pgtable.h arm64: hugetlb: Fix huge_pte_offset to return poisoned page table entries 2017-06-12 16:04:28 +01:00
probes.h arm64: Remove reference to asm/opcodes.h 2016-12-05 10:42:34 +00:00
proc-fns.h arm64: kill flush_cache_all() 2015-05-19 15:27:42 +01:00
processor.h arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP 2017-08-15 18:34:53 +01:00
ptdump.h arm64: dump: Add checking for writable and exectuable pages 2016-11-07 18:15:04 +00:00
ptrace.h arm64: unwind: reference pt_regs via embedded stack frame 2017-08-09 14:07:13 +01:00
seccomp.h arm64: add seccomp support 2014-11-28 10:24:59 +00:00
sections.h arm64: mmu: apply strict permissions to .init.text and .init.data 2017-03-23 13:54:50 +00:00
shmparam.h arm64: fix COMPAT_SHMLBA definition for large pages 2015-12-02 14:00:10 +00:00
signal32.h arm64: Use get_signal() signal_setup_done() 2014-08-06 12:56:16 +02:00
smp_plat.h arm64: remove dead-code depending on CONFIG_UP_LATE_INIT 2015-07-29 18:32:09 +01:00
smp.h arm64: kdump: implement machine_crash_shutdown() 2017-04-05 18:29:15 +01:00
sparsemem.h arm64: mm: update max pa bits to 48 2014-08-19 20:23:02 +01:00
spinlock_types.h arm64: include linux/types.h in asm/spinlock_types.h 2015-07-27 11:09:34 +01:00
spinlock.h arm64 updates for 4.9: 2016-10-03 08:58:35 -07:00
stack_pointer.h arm64: factor out current_stack_pointer 2016-11-11 18:25:43 +00:00
stackprotector.h arm64: ascii armor the arm64 boot init stack canary 2017-07-12 16:26:03 -07:00
stacktrace.h arm64: unwind: remove sp from struct stackframe 2017-08-09 14:10:29 +01:00
stage2_pgtable-nopmd.h kvm: arm64: Get rid of fake page table levels 2016-04-21 14:58:21 +02:00
stage2_pgtable-nopud.h kvm: arm64: Get rid of fake page table levels 2016-04-21 14:58:21 +02:00
stage2_pgtable.h kvm: arm64: Get rid of fake page table levels 2016-04-21 14:58:21 +02:00
stat.h
string.h include/linux/string.h: add the option of fortified string.h functions 2017-07-12 16:26:03 -07:00
suspend.h arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx 2016-11-11 18:25:44 +00:00
sync_bitops.h
syscall.h
sysreg.h arm64: sysreg: Fix unprotected macro argmuent in write_sysreg 2017-07-26 09:28:18 +01:00
system_misc.h Merge branch 'aarch64/for-next/ras-apei' into aarch64/for-next/core 2017-06-26 10:54:27 +01:00
thread_info.h arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP 2017-08-15 18:34:53 +01:00
timex.h
tlb.h arm64: tlbflush: avoid flushing when fullmm == 1 2015-10-07 11:56:21 +01:00
tlbflush.h arm64: Work around Falkor erratum 1009 2017-02-01 15:41:50 +00:00
topology.h arm64, numa: Add NUMA support for arm64 platforms. 2016-04-15 18:06:09 +01:00
traps.h arm64: unwind: reference pt_regs via embedded stack frame 2017-08-09 14:07:13 +01:00
uaccess.h arm64: uaccess: Remove redundant __force from addr cast in __range_ok 2017-07-20 10:20:48 +01:00
unistd32.h Remove compat_sys_getdents64() 2017-04-17 12:52:22 -04:00
unistd.h Remove compat_sys_getdents64() 2017-04-17 12:52:22 -04:00
uprobes.h arm64: Add uprobe support 2016-11-07 18:15:21 +00:00
vdso_datapage.h arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO 2016-07-12 16:06:32 +01:00
vdso.h
virt.h arm64: hyp-stub/KVM: Kill __hyp_get_vectors 2017-04-09 07:49:34 -07:00
word-at-a-time.h Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00