From: Huacai Chen <chenhuacai@kernel.org>
To: Enze Li <lienze@kylinos.cn>
Cc: kernel@xen0n.name, loongarch@lists.linux.dev, glider@google.com,
elver@google.com, akpm@linux-foundation.org,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
zhangqing@loongson.cn, yangtiezhu@loongson.cn,
dvyukov@google.com
Subject: Re: [PATCH 4/4] LoongArch: Add KFENCE support
Date: Wed, 19 Jul 2023 23:27:50 +0800 [thread overview]
Message-ID: <CAAhV-H71sv+VeLfNzuiqitYcuB4rHnho=dRYQftwo1__3bLZSQ@mail.gmail.com> (raw)
In-Reply-To: <20230719082732.2189747-5-lienze@kylinos.cn>
Hi, Enze,
On Wed, Jul 19, 2023 at 4:34 PM Enze Li <lienze@kylinos.cn> wrote:
>
> 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 using 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>
> ---
> arch/loongarch/Kconfig | 1 +
> arch/loongarch/include/asm/kfence.h | 62 ++++++++++++++++++++++++++++
> arch/loongarch/include/asm/pgtable.h | 6 +++
> arch/loongarch/mm/fault.c | 22 ++++++----
> 4 files changed, 83 insertions(+), 8 deletions(-)
> create mode 100644 arch/loongarch/include/asm/kfence.h
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 5411e3a4eb88..db27729003d3 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -93,6 +93,7 @@ config LOONGARCH
> select HAVE_ARCH_JUMP_LABEL
> select HAVE_ARCH_JUMP_LABEL_RELATIVE
> select HAVE_ARCH_KASAN
> + select HAVE_ARCH_KFENCE if 64BIT
"if 64BIT" can be dropped here.
> select HAVE_ARCH_MMAP_RND_BITS if MMU
> select HAVE_ARCH_SECCOMP_FILTER
> select HAVE_ARCH_TRACEHOOK
> diff --git a/arch/loongarch/include/asm/kfence.h b/arch/loongarch/include/asm/kfence.h
> new file mode 100644
> index 000000000000..2a85acc2bc70
> --- /dev/null
> +++ b/arch/loongarch/include/asm/kfence.h
> @@ -0,0 +1,62 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * KFENCE support for LoongArch.
> + *
> + * Author: Enze Li <lienze@kylinos.cn>
> + * Copyright (C) 2022-2023 KylinSoft Corporation.
> + */
> +
> +#ifndef _ASM_LOONGARCH_KFENCE_H
> +#define _ASM_LOONGARCH_KFENCE_H
> +
> +#include <linux/kfence.h>
> +#include <asm/pgtable.h>
> +#include <asm/tlb.h>
> +
> +static inline char *arch_kfence_init_pool(void)
> +{
> + char *__kfence_pool_orig = __kfence_pool;
I prefer kfence_pool than __kfence_pool_orig here.
> + struct vm_struct *area;
> + int err;
> +
> + area = __get_vm_area_caller(KFENCE_POOL_SIZE, VM_IOREMAP,
> + KFENCE_AREA_START, KFENCE_AREA_END,
> + __builtin_return_address(0));
> + if (!area)
> + return NULL;
> +
> + __kfence_pool = (char *)area->addr;
> + err = ioremap_page_range((unsigned long)__kfence_pool,
> + (unsigned long)__kfence_pool + KFENCE_POOL_SIZE,
> + virt_to_phys((void *)__kfence_pool_orig),
> + PAGE_KERNEL);
> + if (err) {
> + free_vm_area(area);
> + return NULL;
> + }
> +
> + return __kfence_pool;
> +}
> +
> +/* Protect the given page and flush TLB. */
> +static inline bool kfence_protect_page(unsigned long addr, bool protect)
> +{
> + pte_t *pte = virt_to_kpte(addr);
> +
> + if (WARN_ON(!pte) || pte_none(*pte))
> + return false;
> +
> + if (protect)
> + set_pte(pte, __pte(pte_val(*pte) & ~(_PAGE_VALID | _PAGE_PRESENT)));
> + else
> + set_pte(pte, __pte(pte_val(*pte) | (_PAGE_VALID | _PAGE_PRESENT)));
> +
> + /* Flush this CPU's TLB. */
> + preempt_disable();
> + local_flush_tlb_one(addr);
> + preempt_enable();
> +
> + return true;
> +}
> +
> +#endif /* _ASM_LOONGARCH_KFENCE_H */
> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
> index 0fc074b8bd48..5a9c81298fe3 100644
> --- a/arch/loongarch/include/asm/pgtable.h
> +++ b/arch/loongarch/include/asm/pgtable.h
> @@ -85,7 +85,13 @@ extern unsigned long zero_page_mask;
> #define MODULES_VADDR (vm_map_base + PCI_IOSIZE + (2 * PAGE_SIZE))
> #define MODULES_END (MODULES_VADDR + SZ_256M)
>
> +#ifdef CONFIG_KFENCE
> +#define KFENCE_AREA_START MODULES_END
> +#define KFENCE_AREA_END (KFENCE_AREA_START + SZ_512M)
Why you choose 512M here?
> +#define VMALLOC_START KFENCE_AREA_END
> +#else
> #define VMALLOC_START MODULES_END
> +#endif
I don't like to put KFENCE_AREA between module and vmalloc range (it
may cause some problems), can we put it after vmemmap?
Huacai
>
> #ifndef CONFIG_KASAN
> #define VMALLOC_END \
> diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c
> index da5b6d518cdb..c0319128b221 100644
> --- a/arch/loongarch/mm/fault.c
> +++ b/arch/loongarch/mm/fault.c
> @@ -23,6 +23,7 @@
> #include <linux/kprobes.h>
> #include <linux/perf_event.h>
> #include <linux/uaccess.h>
> +#include <linux/kfence.h>
>
> #include <asm/branch.h>
> #include <asm/mmu_context.h>
> @@ -30,7 +31,8 @@
>
> int show_unhandled_signals = 1;
>
> -static void __kprobes no_context(struct pt_regs *regs, unsigned long address)
> +static void __kprobes no_context(struct pt_regs *regs, unsigned long address,
> + unsigned long write)
> {
> const int field = sizeof(unsigned long) * 2;
>
> @@ -38,6 +40,9 @@ static void __kprobes no_context(struct pt_regs *regs, unsigned long address)
> if (fixup_exception(regs))
> return;
>
> + if (kfence_handle_page_fault(address, write, regs))
> + return;
> +
> /*
> * Oops. The kernel tried to access some bad page. We'll have to
> * terminate things with extreme prejudice.
> @@ -51,14 +56,15 @@ static void __kprobes no_context(struct pt_regs *regs, unsigned long address)
> die("Oops", regs);
> }
>
> -static void __kprobes do_out_of_memory(struct pt_regs *regs, unsigned long address)
> +static void __kprobes do_out_of_memory(struct pt_regs *regs, unsigned long address,
> + unsigned long write)
> {
> /*
> * We ran out of memory, call the OOM killer, and return the userspace
> * (which will retry the fault, or kill us if we got oom-killed).
> */
> if (!user_mode(regs)) {
> - no_context(regs, address);
> + no_context(regs, address, write);
> return;
> }
> pagefault_out_of_memory();
> @@ -69,7 +75,7 @@ static void __kprobes do_sigbus(struct pt_regs *regs,
> {
> /* Kernel mode? Handle exceptions or die */
> if (!user_mode(regs)) {
> - no_context(regs, address);
> + no_context(regs, address, write);
> return;
> }
>
> @@ -90,7 +96,7 @@ static void __kprobes do_sigsegv(struct pt_regs *regs,
>
> /* Kernel mode? Handle exceptions or die */
> if (!user_mode(regs)) {
> - no_context(regs, address);
> + no_context(regs, address, write);
> return;
> }
>
> @@ -149,7 +155,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs,
> */
> if (address & __UA_LIMIT) {
> if (!user_mode(regs))
> - no_context(regs, address);
> + no_context(regs, address, write);
> else
> do_sigsegv(regs, write, address, si_code);
> return;
> @@ -211,7 +217,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs,
>
> if (fault_signal_pending(fault, regs)) {
> if (!user_mode(regs))
> - no_context(regs, address);
> + no_context(regs, address, write);
> return;
> }
>
> @@ -232,7 +238,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs,
> if (unlikely(fault & VM_FAULT_ERROR)) {
> mmap_read_unlock(mm);
> if (fault & VM_FAULT_OOM) {
> - do_out_of_memory(regs, address);
> + do_out_of_memory(regs, address, write);
> return;
> } else if (fault & VM_FAULT_SIGSEGV) {
> do_sigsegv(regs, write, address, si_code);
> --
> 2.34.1
>
>
next prev parent reply other threads:[~2023-07-19 15:28 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-19 8:27 [PATCH 0/4] Add KFENCE support for LoongArch Enze Li
2023-07-19 8:27 ` [PATCH 1/4] LoongArch: mm: Add page table mapped mode support Enze Li
2023-07-19 15:29 ` Huacai Chen
2023-07-21 2:12 ` Enze Li
2023-07-21 2:21 ` Huacai Chen
2023-07-23 7:17 ` Enze Li
2023-07-25 2:06 ` Huacai Chen
2023-07-25 6:07 ` Enze Li
2023-07-19 8:27 ` [PATCH 2/4] LoongArch: Get stack without NMI when providing regs parameter Enze Li
2023-07-19 15:17 ` Huacai Chen
2023-07-21 1:49 ` Enze Li
2023-07-21 2:17 ` Huacai Chen
2023-07-19 8:27 ` [PATCH 3/4] KFENCE: Deferring the assignment of the local variable addr Enze Li
2023-07-19 10:54 ` Marco Elver
2023-07-19 15:06 ` Huacai Chen
2023-07-19 15:08 ` Marco Elver
2023-07-19 8:27 ` [PATCH 4/4] LoongArch: Add KFENCE support Enze Li
2023-07-19 15:27 ` Huacai Chen [this message]
2023-07-21 3:13 ` Enze Li
2023-07-21 3:19 ` Huacai Chen
2023-07-23 7:34 ` Enze Li
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