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Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Madhavan Srinivasan Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, wangkefeng.wang@huawei.com, Guohanjun References: <20241209024257.3618492-1-tongtiangen@huawei.com> <20241209024257.3618492-3-tongtiangen@huawei.com> From: Ruidong Tian In-Reply-To: <20241209024257.3618492-3-tongtiangen@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi Tong: I applied this path on 6.18 and tested on Kunpeng920, system still alive when i inject a error in copy from user context, but I found that user application receive a SIGBUS, this action is different with x86 machine which return -EFAULT rather than send SIGBUS. I added a patch to fix this behavior[0]. Feel free to incorporate it into your series, or I can send it as a formal follow-up patch, whichever you prefer. [0]: https://github.com/winterddd/linux/tree/arm-copyin Best regards, Ruidong 在 2024/12/9 10:42, Tong Tiangen 写道: > For the arm64 kernel, when it processes hardware memory errors for > synchronize notifications(do_sea()), if the errors is consumed within the > kernel, the current processing is panic. However, it is not optimal. > > Take copy_from/to_user for example, If ld* triggers a memory error, even in > kernel mode, only the associated process is affected. Killing the user > process and isolating the corrupt page is a better choice. > > Add new fixup type EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR to identify insn > that can recover from memory errors triggered by access to kernel memory, > and this fixup type is used in __arch_copy_to_user(), This make the regular > copy_to_user() will handle kernel memory errors. > > Signed-off-by: Tong Tiangen > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/asm-extable.h | 31 +++++++++++++++++++++++----- > arch/arm64/include/asm/asm-uaccess.h | 4 ++++ > arch/arm64/include/asm/extable.h | 1 + > arch/arm64/lib/copy_to_user.S | 10 ++++----- > arch/arm64/mm/extable.c | 19 +++++++++++++++++ > arch/arm64/mm/fault.c | 30 ++++++++++++++++++++------- > 7 files changed, 78 insertions(+), 18 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 100570a048c5..5fa54d31162c 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -21,6 +21,7 @@ config ARM64 > select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE > select ARCH_HAS_CACHE_LINE_SIZE > select ARCH_HAS_CC_PLATFORM > + select ARCH_HAS_COPY_MC if ACPI_APEI_GHES > select ARCH_HAS_CURRENT_STACK_POINTER > select ARCH_HAS_DEBUG_VIRTUAL > select ARCH_HAS_DEBUG_VM_PGTABLE > diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h > index b8a5861dc7b7..0f9123efca0a 100644 > --- a/arch/arm64/include/asm/asm-extable.h > +++ b/arch/arm64/include/asm/asm-extable.h > @@ -5,11 +5,13 @@ > #include > #include > > -#define EX_TYPE_NONE 0 > -#define EX_TYPE_BPF 1 > -#define EX_TYPE_UACCESS_ERR_ZERO 2 > -#define EX_TYPE_KACCESS_ERR_ZERO 3 > -#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 4 > +#define EX_TYPE_NONE 0 > +#define EX_TYPE_BPF 1 > +#define EX_TYPE_UACCESS_ERR_ZERO 2 > +#define EX_TYPE_KACCESS_ERR_ZERO 3 > +#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 4 > +/* kernel access memory error safe */ > +#define EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR 5 > > /* Data fields for EX_TYPE_UACCESS_ERR_ZERO */ > #define EX_DATA_REG_ERR_SHIFT 0 > @@ -51,6 +53,17 @@ > #define _ASM_EXTABLE_UACCESS(insn, fixup) \ > _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, wzr, wzr) > > +#define _ASM_EXTABLE_KACCESS_ERR_ZERO_MEM_ERR(insn, fixup, err, zero) \ > + __ASM_EXTABLE_RAW(insn, fixup, \ > + EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR, \ > + ( \ > + EX_DATA_REG(ERR, err) | \ > + EX_DATA_REG(ZERO, zero) \ > + )) > + > +#define _ASM_EXTABLE_KACCESS_MEM_ERR(insn, fixup) \ > + _ASM_EXTABLE_KACCESS_ERR_ZERO_MEM_ERR(insn, fixup, wzr, wzr) > + > /* > * Create an exception table entry for uaccess `insn`, which will branch to `fixup` > * when an unhandled fault is taken. > @@ -69,6 +82,14 @@ > .endif > .endm > > +/* > + * Create an exception table entry for kaccess `insn`, which will branch to > + * `fixup` when an unhandled fault is taken. > + */ > + .macro _asm_extable_kaccess_mem_err, insn, fixup > + _ASM_EXTABLE_KACCESS_MEM_ERR(\insn, \fixup) > + .endm > + > #else /* __ASSEMBLY__ */ > > #include > diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h > index 5b6efe8abeeb..19aa0180f645 100644 > --- a/arch/arm64/include/asm/asm-uaccess.h > +++ b/arch/arm64/include/asm/asm-uaccess.h > @@ -57,6 +57,10 @@ alternative_else_nop_endif > .endm > #endif > > +#define KERNEL_MEM_ERR(l, x...) \ > +9999: x; \ > + _asm_extable_kaccess_mem_err 9999b, l > + > #define USER(l, x...) \ > 9999: x; \ > _asm_extable_uaccess 9999b, l > diff --git a/arch/arm64/include/asm/extable.h b/arch/arm64/include/asm/extable.h > index 72b0e71cc3de..bc49443bc502 100644 > --- a/arch/arm64/include/asm/extable.h > +++ b/arch/arm64/include/asm/extable.h > @@ -46,4 +46,5 @@ bool ex_handler_bpf(const struct exception_table_entry *ex, > #endif /* !CONFIG_BPF_JIT */ > > bool fixup_exception(struct pt_regs *regs); > +bool fixup_exception_me(struct pt_regs *regs); > #endif > diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S > index 802231772608..bedab1678431 100644 > --- a/arch/arm64/lib/copy_to_user.S > +++ b/arch/arm64/lib/copy_to_user.S > @@ -20,7 +20,7 @@ > * x0 - bytes not copied > */ > .macro ldrb1 reg, ptr, val > - ldrb \reg, [\ptr], \val > + KERNEL_MEM_ERR(9998f, ldrb \reg, [\ptr], \val) > .endm > > .macro strb1 reg, ptr, val > @@ -28,7 +28,7 @@ > .endm > > .macro ldrh1 reg, ptr, val > - ldrh \reg, [\ptr], \val > + KERNEL_MEM_ERR(9998f, ldrh \reg, [\ptr], \val) > .endm > > .macro strh1 reg, ptr, val > @@ -36,7 +36,7 @@ > .endm > > .macro ldr1 reg, ptr, val > - ldr \reg, [\ptr], \val > + KERNEL_MEM_ERR(9998f, ldr \reg, [\ptr], \val) > .endm > > .macro str1 reg, ptr, val > @@ -44,7 +44,7 @@ > .endm > > .macro ldp1 reg1, reg2, ptr, val > - ldp \reg1, \reg2, [\ptr], \val > + KERNEL_MEM_ERR(9998f, ldp \reg1, \reg2, [\ptr], \val) > .endm > > .macro stp1 reg1, reg2, ptr, val > @@ -64,7 +64,7 @@ SYM_FUNC_START(__arch_copy_to_user) > 9997: cmp dst, dstin > b.ne 9998f > // Before being absolutely sure we couldn't copy anything, try harder > - ldrb tmp1w, [srcin] > +KERNEL_MEM_ERR(9998f, ldrb tmp1w, [srcin]) > USER(9998f, sttrb tmp1w, [dst]) > add dst, dst, #1 > 9998: sub x0, end, dst // bytes not copied > diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c > index 228d681a8715..9ad2b6473b60 100644 > --- a/arch/arm64/mm/extable.c > +++ b/arch/arm64/mm/extable.c > @@ -72,7 +72,26 @@ bool fixup_exception(struct pt_regs *regs) > return ex_handler_uaccess_err_zero(ex, regs); > case EX_TYPE_LOAD_UNALIGNED_ZEROPAD: > return ex_handler_load_unaligned_zeropad(ex, regs); > + case EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR: > + return false; > } > > BUG(); > } > + > +bool fixup_exception_me(struct pt_regs *regs) > +{ > + const struct exception_table_entry *ex; > + > + ex = search_exception_tables(instruction_pointer(regs)); > + if (!ex) > + return false; > + > + switch (ex->type) { > + case EX_TYPE_UACCESS_ERR_ZERO: > + case EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR: > + return ex_handler_uaccess_err_zero(ex, regs); > + } > + > + return false; > +} > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index ef63651099a9..278e67357f49 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -801,21 +801,35 @@ static int do_bad(unsigned long far, unsigned long esr, struct pt_regs *regs) > return 1; /* "fault" */ > } > > +/* > + * APEI claimed this as a firmware-first notification. > + * Some processing deferred to task_work before ret_to_user(). > + */ > +static int do_apei_claim_sea(struct pt_regs *regs) > +{ > + int ret; > + > + ret = apei_claim_sea(regs); > + if (ret) > + return ret; > + > + if (!user_mode(regs) && IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC)) { > + if (!fixup_exception_me(regs)) > + return -ENOENT; > + } > + > + return ret; > +} > + > static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs) > { > const struct fault_info *inf; > unsigned long siaddr; > > - inf = esr_to_fault_info(esr); > - > - if (user_mode(regs) && apei_claim_sea(regs) == 0) { > - /* > - * APEI claimed this as a firmware-first notification. > - * Some processing deferred to task_work before ret_to_user(). > - */ > + if (do_apei_claim_sea(regs) == 0) > return 0; > - } > > + inf = esr_to_fault_info(esr); > if (esr & ESR_ELx_FnV) { > siaddr = 0; > } else {