9471f1f2f5
This modifies our user mode stack expansion code to always take the
mmap_lock for writing before modifying the VM layout.
It's actually something we always technically should have done, but
because we didn't strictly need it, we were being lazy ("opportunistic"
sounds so much better, doesn't it?) about things, and had this hack in
place where we would extend the stack vma in-place without doing the
proper locking.
And it worked fine. We just needed to change vm_start (or, in the case
of grow-up stacks, vm_end) and together with some special ad-hoc locking
using the anon_vma lock and the mm->page_table_lock, it all was fairly
straightforward.
That is, it was all fine until Ruihan Li pointed out that now that the
vma layout uses the maple tree code, we *really* don't just change
vm_start and vm_end any more, and the locking really is broken. Oops.
It's not actually all _that_ horrible to fix this once and for all, and
do proper locking, but it's a bit painful. We have basically three
different cases of stack expansion, and they all work just a bit
differently:
- the common and obvious case is the page fault handling. It's actually
fairly simple and straightforward, except for the fact that we have
something like 24 different versions of it, and you end up in a maze
of twisty little passages, all alike.
- the simplest case is the execve() code that creates a new stack.
There are no real locking concerns because it's all in a private new
VM that hasn't been exposed to anybody, but lockdep still can end up
unhappy if you get it wrong.
- and finally, we have GUP and page pinning, which shouldn't really be
expanding the stack in the first place, but in addition to execve()
we also use it for ptrace(). And debuggers do want to possibly access
memory under the stack pointer and thus need to be able to expand the
stack as a special case.
None of these cases are exactly complicated, but the page fault case in
particular is just repeated slightly differently many many times. And
ia64 in particular has a fairly complicated situation where you can have
both a regular grow-down stack _and_ a special grow-up stack for the
register backing store.
So to make this slightly more manageable, the bulk of this series is to
first create a helper function for the most common page fault case, and
convert all the straightforward architectures to it.
Thus the new 'lock_mm_and_find_vma()' helper function, which ends up
being used by x86, arm, powerpc, mips, riscv, alpha, arc, csky, hexagon,
loongarch, nios2, sh, sparc32, and xtensa. So we not only convert more
than half the architectures, we now have more shared code and avoid some
of those twisty little passages.
And largely due to this common helper function, the full diffstat of
this series ends up deleting more lines than it adds.
That still leaves eight architectures (ia64, m68k, microblaze, openrisc,
parisc, s390, sparc64 and um) that end up doing 'expand_stack()'
manually because they are doing something slightly different from the
normal pattern. Along with the couple of special cases in execve() and
GUP.
So there's a couple of patches that first create 'locked' helper
versions of the stack expansion functions, so that there's a obvious
path forward in the conversion. The execve() case is then actually
pretty simple, and is a nice cleanup from our old "grow-up stackls are
special, because at execve time even they grow down".
The #ifdef CONFIG_STACK_GROWSUP in that code just goes away, because
it's just more straightforward to write out the stack expansion there
manually, instead od having get_user_pages_remote() do it for us in some
situations but not others and have to worry about locking rules for GUP.
And the final step is then to just convert the remaining odd cases to a
new world order where 'expand_stack()' is called with the mmap_lock held
for reading, but where it might drop it and upgrade it to a write, only
to return with it held for reading (in the success case) or with it
completely dropped (in the failure case).
In the process, we remove all the stack expansion from GUP (where
dropping the lock wouldn't be ok without special rules anyway), and add
it in manually to __access_remote_vm() for ptrace().
Thanks to Adrian Glaubitz and Frank Scheiner who tested the ia64 cases.
Everything else here felt pretty straightforward, but the ia64 rules for
stack expansion are really quite odd and very different from everything
else. Also thanks to Vegard Nossum who caught me getting one of those
odd conditions entirely the wrong way around.
Anyway, I think I want to actually move all the stack expansion code to
a whole new file of its own, rather than have it split up between
mm/mmap.c and mm/memory.c, but since this will have to be backported to
the initial maple tree vma introduction anyway, I tried to keep the
patches _fairly_ minimal.
Also, while I don't think it's valid to expand the stack from GUP, the
final patch in here is a "warn if some crazy GUP user wants to try to
expand the stack" patch. That one will be reverted before the final
release, but it's left to catch any odd cases during the merge window
and release candidates.
Reported-by: Ruihan Li <lrh2000@pku.edu.cn>
* branch 'expand-stack':
gup: add warning if some caller would seem to want stack expansion
mm: always expand the stack with the mmap write lock held
execve: expand new process stack manually ahead of time
mm: make find_extend_vma() fail if write lock not held
powerpc/mm: convert coprocessor fault to lock_mm_and_find_vma()
mm/fault: convert remaining simple cases to lock_mm_and_find_vma()
arm/mm: Convert to using lock_mm_and_find_vma()
riscv/mm: Convert to using lock_mm_and_find_vma()
mips/mm: Convert to using lock_mm_and_find_vma()
powerpc/mm: Convert to using lock_mm_and_find_vma()
arm64/mm: Convert to using lock_mm_and_find_vma()
mm: make the page fault mmap locking killable
mm: introduce new 'lock_mm_and_find_vma()' page fault helper
8.4 KiB
SPDX-License-Identifier: GPL-2.0-only
config CSKY def_bool y select ARCH_32BIT_OFF_T select ARCH_HAS_DMA_PREP_COHERENT select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_SYNC_DMA_FOR_CPU select ARCH_HAS_SYNC_DMA_FOR_DEVICE select ARCH_USE_BUILTIN_BSWAP select ARCH_USE_QUEUED_RWLOCKS select ARCH_USE_QUEUED_SPINLOCKS select ARCH_HAS_CURRENT_STACK_POINTER select ARCH_INLINE_READ_LOCK if !PREEMPTION select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION select ARCH_INLINE_READ_LOCK_IRQ if !PREEMPTION select ARCH_INLINE_READ_LOCK_IRQSAVE if !PREEMPTION select ARCH_INLINE_READ_UNLOCK if !PREEMPTION select ARCH_INLINE_READ_UNLOCK_BH if !PREEMPTION select ARCH_INLINE_READ_UNLOCK_IRQ if !PREEMPTION select ARCH_INLINE_READ_UNLOCK_IRQRESTORE if !PREEMPTION select ARCH_INLINE_WRITE_LOCK if !PREEMPTION select ARCH_INLINE_WRITE_LOCK_BH if !PREEMPTION select ARCH_INLINE_WRITE_LOCK_IRQ if !PREEMPTION select ARCH_INLINE_WRITE_LOCK_IRQSAVE if !PREEMPTION select ARCH_INLINE_WRITE_UNLOCK if !PREEMPTION select ARCH_INLINE_WRITE_UNLOCK_BH if !PREEMPTION select ARCH_INLINE_WRITE_UNLOCK_IRQ if !PREEMPTION select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE if !PREEMPTION select ARCH_INLINE_SPIN_TRYLOCK if !PREEMPTION select ARCH_INLINE_SPIN_TRYLOCK_BH if !PREEMPTION select ARCH_INLINE_SPIN_LOCK if !PREEMPTION select ARCH_INLINE_SPIN_LOCK_BH if !PREEMPTION select ARCH_INLINE_SPIN_LOCK_IRQ if !PREEMPTION select ARCH_INLINE_SPIN_LOCK_IRQSAVE if !PREEMPTION select ARCH_INLINE_SPIN_UNLOCK if !PREEMPTION select ARCH_INLINE_SPIN_UNLOCK_BH if !PREEMPTION select ARCH_INLINE_SPIN_UNLOCK_IRQ if !PREEMPTION select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE if !PREEMPTION select ARCH_WANT_FRAME_POINTERS if !CPU_CK610 && $(cc-option,-mbacktrace) select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT select COMMON_CLK select CLKSRC_MMIO select CSKY_MPINTC if CPU_CK860 select CSKY_MP_TIMER if CPU_CK860 select CSKY_APB_INTC select DMA_DIRECT_REMAP select IRQ_DOMAIN select DW_APB_TIMER_OF select GENERIC_IOREMAP select GENERIC_LIB_ASHLDI3 select GENERIC_LIB_ASHRDI3 select GENERIC_LIB_LSHRDI3 select GENERIC_LIB_MULDI3 select GENERIC_LIB_CMPDI2 select GENERIC_LIB_UCMPDI2 select GENERIC_ALLOCATOR select GENERIC_ATOMIC64 select GENERIC_CPU_DEVICES select GENERIC_IRQ_CHIP select GENERIC_IRQ_PROBE select GENERIC_IRQ_SHOW select GENERIC_IRQ_MULTI_HANDLER select GENERIC_SCHED_CLOCK select GENERIC_SMP_IDLE_THREAD select GENERIC_TIME_VSYSCALL select GENERIC_VDSO_32 select GENERIC_GETTIMEOFDAY select GX6605S_TIMER if CPU_CK610 select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_JUMP_LABEL if !CPU_CK610 select HAVE_ARCH_JUMP_LABEL_RELATIVE select HAVE_ARCH_MMAP_RND_BITS select HAVE_ARCH_SECCOMP_FILTER select HAVE_CONTEXT_TRACKING_USER select HAVE_VIRT_CPU_ACCOUNTING_GEN select HAVE_DEBUG_BUGVERBOSE select HAVE_DEBUG_KMEMLEAK select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_REGS select HAVE_GENERIC_VDSO select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_ERROR_INJECTION select HAVE_FTRACE_MCOUNT_RECORD select HAVE_KERNEL_GZIP select HAVE_KERNEL_LZO select HAVE_KERNEL_LZMA select HAVE_KPROBES if !CPU_CK610 select HAVE_KPROBES_ON_FTRACE if !CPU_CK610 select HAVE_KRETPROBES if !CPU_CK610 select HAVE_PERF_EVENTS select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP select HAVE_DMA_CONTIGUOUS select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_STACKPROTECTOR select HAVE_SYSCALL_TRACEPOINTS select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU select LOCK_MM_AND_FIND_VMA select MAY_HAVE_SPARSE_IRQ select MODULES_USE_ELF_RELA if MODULES select OF select OF_EARLY_FLATTREE select PERF_USE_VMALLOC if CPU_CK610 select RTC_LIB select TIMER_OF select GENERIC_PCI_IOMAP select HAVE_PCI select PCI_DOMAINS_GENERIC if PCI select PCI_SYSCALL if PCI select PCI_MSI if PCI select TRACE_IRQFLAGS_SUPPORT
config LOCKDEP_SUPPORT def_bool y
config ARCH_SUPPORTS_UPROBES def_bool y if !CPU_CK610
config CPU_HAS_CACHEV2 bool
config CPU_HAS_FPUV2 bool
config CPU_HAS_HILO bool
config CPU_HAS_TLBI bool
config CPU_HAS_LDSTEX bool help For SMP, CPU needs "ldex&stex" instructions for atomic operations.
config CPU_NEED_TLBSYNC bool
config CPU_NEED_SOFTALIGN bool
config CPU_NO_USER_BKPT bool help For abiv2 we couldn't use "trap 1" as user space bkpt in gdbserver, because abiv2 is 16/32bit instruction set and "trap 1" is 32bit. So we need a 16bit instruction as user space bkpt, and it will cause an illegal instruction exception. In kernel we parse the *regs->pc to determine whether to send SIGTRAP or not.
config GENERIC_CALIBRATE_DELAY def_bool y
config GENERIC_CSUM def_bool y
config GENERIC_HWEIGHT def_bool y
config MMU def_bool y
config STACKTRACE_SUPPORT def_bool y
config TIME_LOW_RES def_bool y
config CPU_ASID_BITS int default "8" if (CPU_CK610 || CPU_CK807 || CPU_CK810) default "12" if (CPU_CK860)
config L1_CACHE_SHIFT int default "4" if (CPU_CK610) default "5" if (CPU_CK807 || CPU_CK810) default "6" if (CPU_CK860)
config ARCH_MMAP_RND_BITS_MIN default 8
max bits determined by the following formula:
VA_BITS - PAGE_SHIFT - 3
config ARCH_MMAP_RND_BITS_MAX default 17
menu "Processor type and features"
choice prompt "CPU MODEL" default CPU_CK807
config CPU_CK610 bool "CSKY CPU ck610" select CPU_NEED_TLBSYNC select CPU_NEED_SOFTALIGN select CPU_NO_USER_BKPT
config CPU_CK810 bool "CSKY CPU ck810" select CPU_HAS_HILO select CPU_NEED_TLBSYNC
config CPU_CK807 bool "CSKY CPU ck807" select CPU_HAS_HILO
config CPU_CK860 bool "CSKY CPU ck860" select CPU_HAS_TLBI select CPU_HAS_CACHEV2 select CPU_HAS_LDSTEX select CPU_HAS_FPUV2 endchoice
choice prompt "PAGE OFFSET" default PAGE_OFFSET_80000000
config PAGE_OFFSET_80000000 bool "PAGE OFFSET 2G (user:kernel = 2:2)"
config PAGE_OFFSET_A0000000 bool "PAGE OFFSET 2.5G (user:kernel = 2.5:1.5)" endchoice
config PAGE_OFFSET hex default 0x80000000 if PAGE_OFFSET_80000000 default 0xa0000000 if PAGE_OFFSET_A0000000 choice
prompt "C-SKY PMU type"
depends on PERF_EVENTS
depends on CPU_CK807 || CPU_CK810 || CPU_CK860
config CPU_PMU_NONE bool "None"
config CSKY_PMU_V1 bool "Performance Monitoring Unit Ver.1"
endchoice
choice prompt "Power Manager Instruction (wait/doze/stop)" default CPU_PM_NONE
config CPU_PM_NONE bool "None"
config CPU_PM_WAIT bool "wait"
config CPU_PM_DOZE bool "doze"
config CPU_PM_STOP bool "stop" endchoice
menuconfig HAVE_TCM bool "Tightly-Coupled/Sram Memory" depends on !COMPILE_TEST help The implementation are not only used by TCM (Tightly-Coupled Memory) but also used by sram on SOC bus. It follow existed linux tcm software interface, so that old tcm application codes could be re-used directly.
if HAVE_TCM config ITCM_RAM_BASE hex "ITCM ram base" default 0xffffffff
config ITCM_NR_PAGES int "Page count of ITCM size: NR*4KB" range 1 256 default 32
config HAVE_DTCM bool "DTCM Support"
config DTCM_RAM_BASE hex "DTCM ram base" depends on HAVE_DTCM default 0xffffffff
config DTCM_NR_PAGES int "Page count of DTCM size: NR*4KB" depends on HAVE_DTCM range 1 256 default 32 endif
config CPU_HAS_VDSP bool "CPU has VDSP coprocessor" depends on CPU_HAS_FPU && CPU_HAS_FPUV2
config CPU_HAS_FPU bool "CPU has FPU coprocessor" depends on CPU_CK807 || CPU_CK810 || CPU_CK860
config CPU_HAS_ICACHE_INS bool "CPU has Icache invalidate instructions" depends on CPU_HAS_CACHEV2
config CPU_HAS_TEE bool "CPU has Trusted Execution Environment" depends on CPU_CK810
config SMP bool "Symmetric Multi-Processing (SMP) support for C-SKY" depends on CPU_CK860 default n
config NR_CPUS int "Maximum number of CPUs (2-32)" range 2 32 depends on SMP default "4"
config HIGHMEM bool "High Memory Support" depends on !CPU_CK610 select KMAP_LOCAL default y
config DRAM_BASE hex "DRAM start addr (the same with memory-section in dts)" default 0x0
config HOTPLUG_CPU bool "Support for hot-pluggable CPUs" select GENERIC_IRQ_MIGRATION depends on SMP help Say Y here to allow turning CPUs off and on. CPUs can be controlled through /sys/devices/system/cpu/cpu1/hotplug/target.
Say N if you want to disable CPU hotplug.
config HAVE_EFFICIENT_UNALIGNED_STRING_OPS bool "Enable EFFICIENT_UNALIGNED_STRING_OPS for abiv2" depends on CPU_CK807 || CPU_CK810 || CPU_CK860 help Say Y here to enable EFFICIENT_UNALIGNED_STRING_OPS. Some CPU models could deal with unaligned access by hardware.
endmenu
source "arch/csky/Kconfig.platforms"
source "kernel/Kconfig.hz"