LoongArch: Fix access error when read fault on a write-only VMA

As with most architectures, allow handling of read faults in VMAs that
have VM_WRITE but without VM_READ (WRITE implies READ).

Otherwise, reading before writing a write-only memory will error while
reading after writing everything is fine.

BTW, move the VM_EXEC judgement before VM_READ/VM_WRITE to make logic a
little clearer.

Cc: stable@vger.kernel.org
Fixes: 09cfefb7fa70c3af01 ("LoongArch: Add memory management")
Signed-off-by: Jiantao Shan <shanjiantao@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Fix some build warnings with W=1

There are some building warnings when building LoongArch kernel with W=1
as following, this patch fixes them.

arch/loongarch/kernel/acpi.c:284:13: warning: no previous prototype for ‘acpi_numa_arch_fixup’ [-Wmissing-prototypes]
284 | void __init acpi_numa_arch_fixup(void) {}
| ^~~~~~~~~~~~~~~~~~~~
arch/loongarch/kernel/time.c:32:13: warning: no previous prototype for ‘constant_timer_interrupt’ [-Wmissing-prototypes]
32 | irqreturn_t constant_timer_interrupt(int irq, void *data)
| ^~~~~~~~~~~~~~~~~~~~~~~~
arch/loongarch/kernel/traps.c:496:25: warning: no previous prototype for 'do_fpe' [-Wmissing-prototypes]
496 | asmlinkage void noinstr do_fpe(struct pt_regs *regs
| ^~~~~~
arch/loongarch/kernel/traps.c:813:22: warning: variable ‘opcode’ set but not used [-Wunused-but-set-variable]
813 | unsigned int opcode;
| ^~~~~~
arch/loongarch/kernel/signal.c:895:14: warning: no previous prototype for ‘get_sigframe’ [-Wmissing-prototypes]
895 | void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
| ^~~~~~~~~~~~
arch/loongarch/kernel/syscall.c:21:40: warning: initialized field overwritten [-Woverride-init]
21 | #define __SYSCALL(nr, call) [nr] = (call),
| ^
arch/loongarch/kernel/syscall.c:40:14: warning: no previous prototype for ‘do_syscall’ [-Wmissing-prototypes]
40 | void noinstr do_syscall(struct pt_regs *regs)
| ^~~~~~~~~~
arch/loongarch/kernel/smp.c:502:17: warning: no previous prototype for ‘start_secondary’ [-Wmissing-prototypes]
502 | asmlinkage void start_secondary(void)
| ^~~~~~~~~~~~~~~
arch/loongarch/kernel/process.c:309:15: warning: no previous prototype for ‘arch_align_stack’ [-Wmissing-prototypes]
309 | unsigned long arch_align_stack(unsigned long sp)
| ^~~~~~~~~~~~~~~~
arch/loongarch/kernel/topology.c:13:5: warning: no previous prototype for ‘arch_register_cpu’ [-Wmissing-prototypes]
13 | int arch_register_cpu(int cpu)
| ^~~~~~~~~~~~~~~~~
arch/loongarch/kernel/topology.c:27:6: warning: no previous prototype for ‘arch_unregister_cpu’ [-Wmissing-prototypes]
27 | void arch_unregister_cpu(int cpu)
| ^~~~~~~~~~~~~~~~~~~
arch/loongarch/kernel/module-sections.c:103:5: warning: no previous prototype for ‘module_frob_arch_sections’ [-Wmissing-prototypes]
103 | int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
| ^~~~~~~~~~~~~~~~~~~~~~~~~
arch/loongarch/mm/hugetlbpage.c:56:5: warning: no previous prototype for ‘is_aligned_hugepage_range’ [-Wmissing-prototypes]
56 | int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
| ^~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Add KFENCE (Kernel Electric-Fence) support

The LoongArch architecture is quite different from other architectures.
When the allocating of KFENCE itself is done, it is mapped to the direct
mapping configuration window [1] by default on LoongArch. It means that
it is not possible to use the page table mapped mode which required by
the KFENCE system and therefore it should be remapped to the appropriate
region.

This patch adds architecture specific implementation details for KFENCE.
In particular, this implements the required interface in <asm/kfence.h>.

Tested this patch by running the testcases and all passed.

[1] https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#virtual-address-space-and-address-translation-mode

Signed-off-by: Enze Li <lienze@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

mm/fault: convert remaining simple cases to lock_mm_and_find_vma()

This does the simple pattern conversion of alpha, arc, csky, hexagon,
loongarch, nios2, sh, sparc32, and xtensa to the lock_mm_and_find_vma()
helper. They all have the regular fault handling pattern without odd
special cases.

The remaining architectures all have something that keeps us from a
straightforward conversion: ia64 and parisc have stacks that can grow
both up as well as down (and ia64 has special address region checks).

And m68k, microblaze, openrisc, sparc64, and um end up having extra
rules about only expanding the stack down a limited amount below the
user space stack pointer. That is something that x86 used to do too
(long long ago), and it probably could just be skipped, but it still
makes the conversion less than trivial.

Note that this conversion was done manually and with the exception of
alpha without any build testing, because I have a fairly limited cross-
building environment. The cases are all simple, and I went through the
changes several times, but...

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

LoongArch: Add kprobes support

Kprobes allows you to trap at almost any kernel address and execute a
callback function, this commit adds kprobes support for LoongArch.

Tested-by: Jeff Xie <xiehuan09@gmail.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: mm: Avoid unnecessary page fault retires on shared memory types

Commit d92725256b4f22d0 ("mm: avoid unnecessary page fault retires on
shared memory types") modifies do_page_fault() to handle the VM_FAULT_
COMPLETED case, but forget to change for LoongArch, so fix it as other
architectures does.

Fixes: d92725256b4f22d0 ("mm: avoid unnecessary page fault retires on shared memory types")
Reviewed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Add memory management

Add memory management support for LoongArch, including: cache and tlb
management, page fault handling and ioremap/mmap support.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>