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[23.128.96.18]) by mx.google.com with ESMTP id n8si8015573plh.598.2022.01.21.14.31.00; Fri, 21 Jan 2022 14:31:14 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@ventanamicro.com header.s=google header.b=UuAosnS4; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244163AbiATSQO (ORCPT + 99 others); Thu, 20 Jan 2022 13:16:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243993AbiATSQN (ORCPT ); Thu, 20 Jan 2022 13:16:13 -0500 Received: from mail-lf1-x135.google.com (mail-lf1-x135.google.com [IPv6:2a00:1450:4864:20::135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1AFB6C06173F for ; Thu, 20 Jan 2022 10:16:13 -0800 (PST) Received: by mail-lf1-x135.google.com with SMTP id x11so24885334lfa.2 for ; Thu, 20 Jan 2022 10:16:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ventanamicro.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=J9x2NG+LgE4kaD5UG5LUL0GB0NdPSyzMtwcN6xwlv9c=; b=UuAosnS4uZq9DoXlhTBm4j5l2w1d3uzS1YTDRfj9LBQyPwlz6lHwa3/ypLEr5zmS7k pt/lZDx7hlGBC3crCBzVwmp8t2ixX5/2a0nkfDSp4Kru+pSVPKZtUWhqQYcVdiN5HiUO WpBGKcJpqU7V4pg5PTUGwatPlL+giv/QcjBc3qGRjWYM34j4EdkN+kNyDOqhr54G64ry WWzRfIpb+bYWwx/wBMHhTNpDyimr/Mld0kgdo/BCjycjgRXREiZ8gzJzne/VND60di8c b3wv3kQRT+j0JNBpWPwbhpQzAdrDopXsBMpjb7d3wS2tLfFVQDndXur5qLVBLLAmStJt nU+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=J9x2NG+LgE4kaD5UG5LUL0GB0NdPSyzMtwcN6xwlv9c=; b=kVCXfcHtI7taTF2WpSfc8oT+HiaG5apK0ratWMpCG8cvUvoAJRNHYkgG0iq8gPxf1z 8pjLkO1Qbu8PaHuClesWZaItQkoDc/EhODi1qsLL2VG/CbL60IevlKhiLxOeCMBxFdIY LGecHh4n7WP9rweoGAo1CfwWG3Up1AQ4yHc/wrahO6xizamoiTNuwiFUVpSlIY7kmNye JTzCT+MQc2XtsCCVoDw1RS3N+H018410c7/lKn7Vg5J9f9sxjvawXl6v36XgS8HOEOfL unlwZymWXXjlNHEzEmv+vKMFdoc3SQNKDgwI40uK98kCn9KB6YmDr9lOHcr7zi8mD45f i5Mg== X-Gm-Message-State: AOAM533OIjw6jS5Np6xXuYh+4no3vCmh+wblkG8kkNiMLfrYeSxYitRb O97ewSCtVrpK+u/aY4PbZBQ/TT3r5pyLyIONzPoMVA== X-Received: by 2002:a05:6512:130f:: with SMTP id x15mr242448lfu.587.1642702571197; Thu, 20 Jan 2022 10:16:11 -0800 (PST) MIME-Version: 1.0 References: <20211118192130.48b8f04c@xhacker> <20211118192651.605d0c80@xhacker> In-Reply-To: <20211118192651.605d0c80@xhacker> From: Mayuresh Chitale Date: Thu, 20 Jan 2022 23:45:34 +0530 Message-ID: Subject: Re: [PATCH 11/12] riscv: extable: add a dedicated uaccess handler To: Jisheng Zhang Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Masahiro Yamada , Michal Marek , Nick Desaulniers , Kefeng Wang , Tong Tiangen , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kbuild@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Jisheng, Just wanted to inform you that this patch breaks the writev02 test case in LTP and if it is reverted then the test passes. If we run the test through strace then we see that the test hangs and following is the last line printed by strace: "writev(3, [{iov_base=0x7fff848a6000, iov_len=8192}, {iov_base=NULL, iov_len=0}]" Thanks, Mayuresh. On Thu, Nov 18, 2021 at 5:05 PM Jisheng Zhang wrote: > > From: Jisheng Zhang > > Inspired by commit 2e77a62cb3a6("arm64: extable: add a dedicated > uaccess handler"), do similar to riscv to add a dedicated uaccess > exception handler to update registers in exception context and > subsequently return back into the function which faulted, so we remove > the need for fixups specialized to each faulting instruction. > > Signed-off-by: Jisheng Zhang > --- > arch/riscv/include/asm/asm-extable.h | 23 +++++++++ > arch/riscv/include/asm/futex.h | 23 +++------ > arch/riscv/include/asm/uaccess.h | 74 +++++++++------------------- > arch/riscv/mm/extable.c | 27 ++++++++++ > 4 files changed, 78 insertions(+), 69 deletions(-) > > diff --git a/arch/riscv/include/asm/asm-extable.h b/arch/riscv/include/asm/asm-extable.h > index 1b1f4ffd8d37..14be0673f5b5 100644 > --- a/arch/riscv/include/asm/asm-extable.h > +++ b/arch/riscv/include/asm/asm-extable.h > @@ -5,6 +5,7 @@ > #define EX_TYPE_NONE 0 > #define EX_TYPE_FIXUP 1 > #define EX_TYPE_BPF 2 > +#define EX_TYPE_UACCESS_ERR_ZERO 3 > > #ifdef __ASSEMBLY__ > > @@ -23,7 +24,9 @@ > > #else /* __ASSEMBLY__ */ > > +#include > #include > +#include > > #define __ASM_EXTABLE_RAW(insn, fixup, type, data) \ > ".pushsection __ex_table, \"a\"\n" \ > @@ -37,6 +40,26 @@ > #define _ASM_EXTABLE(insn, fixup) \ > __ASM_EXTABLE_RAW(#insn, #fixup, __stringify(EX_TYPE_FIXUP), "0") > > +#define EX_DATA_REG_ERR_SHIFT 0 > +#define EX_DATA_REG_ERR GENMASK(4, 0) > +#define EX_DATA_REG_ZERO_SHIFT 5 > +#define EX_DATA_REG_ZERO GENMASK(9, 5) > + > +#define EX_DATA_REG(reg, gpr) \ > + "((.L__gpr_num_" #gpr ") << " __stringify(EX_DATA_REG_##reg##_SHIFT) ")" > + > +#define _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, zero) \ > + __DEFINE_ASM_GPR_NUMS \ > + __ASM_EXTABLE_RAW(#insn, #fixup, \ > + __stringify(EX_TYPE_UACCESS_ERR_ZERO), \ > + "(" \ > + EX_DATA_REG(ERR, err) " | " \ > + EX_DATA_REG(ZERO, zero) \ > + ")") > + > +#define _ASM_EXTABLE_UACCESS_ERR(insn, fixup, err) \ > + _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, zero) > + > #endif /* __ASSEMBLY__ */ > > #endif /* __ASM_ASM_EXTABLE_H */ > diff --git a/arch/riscv/include/asm/futex.h b/arch/riscv/include/asm/futex.h > index 2e15e8e89502..fc8130f995c1 100644 > --- a/arch/riscv/include/asm/futex.h > +++ b/arch/riscv/include/asm/futex.h > @@ -21,20 +21,14 @@ > > #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \ > { \ > - uintptr_t tmp; \ > __enable_user_access(); \ > __asm__ __volatile__ ( \ > "1: " insn " \n" \ > "2: \n" \ > - " .section .fixup,\"ax\" \n" \ > - " .balign 4 \n" \ > - "3: li %[r],%[e] \n" \ > - " jump 2b,%[t] \n" \ > - " .previous \n" \ > - _ASM_EXTABLE(1b, 3b) \ > + _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %[r]) \ > : [r] "+r" (ret), [ov] "=&r" (oldval), \ > - [u] "+m" (*uaddr), [t] "=&r" (tmp) \ > - : [op] "Jr" (oparg), [e] "i" (-EFAULT) \ > + [u] "+m" (*uaddr) \ > + : [op] "Jr" (oparg) \ > : "memory"); \ > __disable_user_access(); \ > } > @@ -96,15 +90,10 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, > "2: sc.w.aqrl %[t],%z[nv],%[u] \n" > " bnez %[t],1b \n" > "3: \n" > - " .section .fixup,\"ax\" \n" > - " .balign 4 \n" > - "4: li %[r],%[e] \n" > - " jump 3b,%[t] \n" > - " .previous \n" > - _ASM_EXTABLE(1b, 4b) \ > - _ASM_EXTABLE(2b, 4b) \ > + _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %[r]) \ > + _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %[r]) \ > : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp) > - : [ov] "Jr" (oldval), [nv] "Jr" (newval), [e] "i" (-EFAULT) > + : [ov] "Jr" (oldval), [nv] "Jr" (newval) > : "memory"); > __disable_user_access(); > > diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h > index 40e6099af488..a4716c026386 100644 > --- a/arch/riscv/include/asm/uaccess.h > +++ b/arch/riscv/include/asm/uaccess.h > @@ -81,22 +81,14 @@ static inline int __access_ok(unsigned long addr, unsigned long size) > > #define __get_user_asm(insn, x, ptr, err) \ > do { \ > - uintptr_t __tmp; \ > __typeof__(x) __x; \ > __asm__ __volatile__ ( \ > "1:\n" \ > - " " insn " %1, %3\n" \ > + " " insn " %1, %2\n" \ > "2:\n" \ > - " .section .fixup,\"ax\"\n" \ > - " .balign 4\n" \ > - "3:\n" \ > - " li %0, %4\n" \ > - " li %1, 0\n" \ > - " jump 2b, %2\n" \ > - " .previous\n" \ > - _ASM_EXTABLE(1b, 3b) \ > - : "+r" (err), "=&r" (__x), "=r" (__tmp) \ > - : "m" (*(ptr)), "i" (-EFAULT)); \ > + _ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 2b, %0, %1) \ > + : "+r" (err), "=&r" (__x) \ > + : "m" (*(ptr))); \ > (x) = __x; \ > } while (0) > > @@ -108,27 +100,18 @@ do { \ > do { \ > u32 __user *__ptr = (u32 __user *)(ptr); \ > u32 __lo, __hi; \ > - uintptr_t __tmp; \ > __asm__ __volatile__ ( \ > "1:\n" \ > - " lw %1, %4\n" \ > + " lw %1, %3\n" \ > "2:\n" \ > - " lw %2, %5\n" \ > + " lw %2, %4\n" \ > "3:\n" \ > - " .section .fixup,\"ax\"\n" \ > - " .balign 4\n" \ > - "4:\n" \ > - " li %0, %6\n" \ > - " li %1, 0\n" \ > - " li %2, 0\n" \ > - " jump 3b, %3\n" \ > - " .previous\n" \ > - _ASM_EXTABLE(1b, 4b) \ > - _ASM_EXTABLE(2b, 4b) \ > - : "+r" (err), "=&r" (__lo), "=r" (__hi), \ > - "=r" (__tmp) \ > - : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]), \ > - "i" (-EFAULT)); \ > + _ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 3b, %0, %1) \ > + _ASM_EXTABLE_UACCESS_ERR_ZERO(2b, 3b, %0, %1) \ > + : "+r" (err), "=&r" (__lo), "=r" (__hi) \ > + : "m" (__ptr[__LSW]), "m" (__ptr[__MSW])) \ > + if (err) \ > + __hi = 0; \ > (x) = (__typeof__(x))((__typeof__((x)-(x)))( \ > (((u64)__hi << 32) | __lo))); \ > } while (0) > @@ -216,21 +199,14 @@ do { \ > > #define __put_user_asm(insn, x, ptr, err) \ > do { \ > - uintptr_t __tmp; \ > __typeof__(*(ptr)) __x = x; \ > __asm__ __volatile__ ( \ > "1:\n" \ > - " " insn " %z3, %2\n" \ > + " " insn " %z2, %1\n" \ > "2:\n" \ > - " .section .fixup,\"ax\"\n" \ > - " .balign 4\n" \ > - "3:\n" \ > - " li %0, %4\n" \ > - " jump 2b, %1\n" \ > - " .previous\n" \ > - _ASM_EXTABLE(1b, 3b) \ > - : "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \ > - : "rJ" (__x), "i" (-EFAULT)); \ > + _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %0) \ > + : "+r" (err), "=m" (*(ptr)) \ > + : "rJ" (__x)); \ > } while (0) > > #ifdef CONFIG_64BIT > @@ -244,22 +220,16 @@ do { \ > uintptr_t __tmp; \ > __asm__ __volatile__ ( \ > "1:\n" \ > - " sw %z4, %2\n" \ > + " sw %z3, %1\n" \ > "2:\n" \ > - " sw %z5, %3\n" \ > + " sw %z4, %2\n" \ > "3:\n" \ > - " .section .fixup,\"ax\"\n" \ > - " .balign 4\n" \ > - "4:\n" \ > - " li %0, %6\n" \ > - " jump 3b, %1\n" \ > - " .previous\n" \ > - _ASM_EXTABLE(1b, 4b) \ > - _ASM_EXTABLE(2b, 4b) \ > - : "+r" (err), "=r" (__tmp), \ > + _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %0) \ > + _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %0) \ > + : "+r" (err), \ > "=m" (__ptr[__LSW]), \ > "=m" (__ptr[__MSW]) \ > - : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \ > + : "rJ" (__x), "rJ" (__x >> 32)); \ > } while (0) > #endif /* CONFIG_64BIT */ > > diff --git a/arch/riscv/mm/extable.c b/arch/riscv/mm/extable.c > index 91e52c4bb33a..05978f78579f 100644 > --- a/arch/riscv/mm/extable.c > +++ b/arch/riscv/mm/extable.c > @@ -7,10 +7,12 @@ > */ > > > +#include > #include > #include > #include > #include > +#include > > static inline unsigned long > get_ex_fixup(const struct exception_table_entry *ex) > @@ -25,6 +27,29 @@ static bool ex_handler_fixup(const struct exception_table_entry *ex, > return true; > } > > +static inline void regs_set_gpr(struct pt_regs *regs, unsigned int offset, > + unsigned long val) > +{ > + if (unlikely(offset > MAX_REG_OFFSET)) > + return; > + > + if (!offset) > + *(unsigned long *)((unsigned long)regs + offset) = val; > +} > + > +static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex, > + struct pt_regs *regs) > +{ > + int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data); > + int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data); > + > + regs_set_gpr(regs, reg_err, -EFAULT); > + regs_set_gpr(regs, reg_zero, 0); > + > + regs->epc = get_ex_fixup(ex); > + return true; > +} > + > bool fixup_exception(struct pt_regs *regs) > { > const struct exception_table_entry *ex; > @@ -38,6 +63,8 @@ bool fixup_exception(struct pt_regs *regs) > return ex_handler_fixup(ex, regs); > case EX_TYPE_BPF: > return ex_handler_bpf(ex, regs); > + case EX_TYPE_UACCESS_ERR_ZERO: > + return ex_handler_uaccess_err_zero(ex, regs); > } > > BUG(); > -- > 2.33.0 > > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv