[07/12] riscv: lib: uaccess: fold fixups into body

Message ID	20211118192514.13d3e873@xhacker (mailing list archive)
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Headers	show Return-Path: <SRS0=Kh2H=QF=lists.infradead.org=linux-riscv-bounces+linux-riscv=archiver.kernel.org@kernel.org> DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EBA1761BAA Date: Thu, 18 Nov 2021 19:25:14 +0800 From: Jisheng Zhang <jszhang3@mail.ustc.edu.cn> To: Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, " =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= " <bjorn@kernel.org>, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>, John Fastabend <john.fastabend@gmail.com>, KP Singh <kpsingh@kernel.org>, Masahiro Yamada <masahiroy@kernel.org>, Michal Marek <michal.lkml@markovi.net>, Nick Desaulniers <ndesaulniers@google.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com>, Tong Tiangen <tongtiangen@huawei.com>, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kbuild@vger.kernel.org Subject: [PATCH 07/12] riscv: lib: uaccess: fold fixups into body Message-ID: <20211118192514.13d3e873@xhacker> In-Reply-To: <20211118192130.48b8f04c@xhacker> References: <20211118192130.48b8f04c@xhacker> MIME-Version: 1.0 Precedence: list Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" <linux-riscv-bounces@lists.infradead.org> Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org
Series	riscv: switch to relative extable and other improvements \| expand [v4,0/12] riscv: switch to relative extable and other improvements [01/12] riscv: remove unused __cmpxchg_user() macro [02/12] riscv: consolidate __ex_table construction [03/12] riscv: switch to relative exception tables [04/12] riscv: bpf: move rv_bpf_fixup_exception signature to extable.h [05/12] riscv: extable: make fixup_exception() return bool [06/12] riscv: extable: use `ex` for `exception_table_entry` [07/12] riscv: lib: uaccess: fold fixups into body [08/12] riscv: extable: consolidate definitions [09/12] riscv: extable: add `type` and `data` fields [10/12] riscv: add gpr-num.h [11/12] riscv: extable: add a dedicated uaccess handler [12/12] riscv: vmlinux.lds.S\|vmlinux-xip.lds.S: remove `.fixup` section

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20211118192514.13d3e873@xhacker (mailing list archive)

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DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EBA1761BAA
Date: Thu, 18 Nov 2021 19:25:14 +0800
From: Jisheng Zhang <jszhang3@mail.ustc.edu.cn>
To: Paul Walmsley <paul.walmsley@sifive.com>,
 Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, "
	=?utf-8?b?QmrDtnJuIFTDtnBlbA==?= " <bjorn@kernel.org>,
 Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>,
 Andrii Nakryiko <andrii@kernel.org>, Martin KaFai Lau <kafai@fb.com>,
 Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
 John Fastabend <john.fastabend@gmail.com>, KP Singh <kpsingh@kernel.org>,
 Masahiro Yamada <masahiroy@kernel.org>,
 Michal Marek <michal.lkml@markovi.net>,
 Nick Desaulniers <ndesaulniers@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>, Tong Tiangen
 <tongtiangen@huawei.com>, linux-riscv@lists.infradead.org,
 linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org,
 linux-kbuild@vger.kernel.org
Subject: [PATCH 07/12] riscv: lib: uaccess: fold fixups into body
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Series

riscv: switch to relative extable and other improvements | expand

Commit Message

Jisheng Zhang Nov. 18, 2021, 11:25 a.m. UTC

From: Jisheng Zhang <jszhang@kernel.org>

uaccess functions such __asm_copy_to_user(),  __arch_copy_from_user()
and __clear_user() place their exception fixups in the `.fixup` section
without any clear association with themselves. If we backtrace the
fixup code, it will be symbolized as an offset from the nearest prior
symbol.

Similar as arm64 does, we must move fixups into the body of the
functions themselves, after the usual fast-path returns.

Inline assembly will be dealt with in subsequent patches.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/lib/uaccess.S | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S
index 55f80f84e23f..047f517ac780 100644
--- a/arch/riscv/lib/uaccess.S
+++ b/arch/riscv/lib/uaccess.S
@@ -173,6 +173,13 @@  ENTRY(__asm_copy_from_user)
 	csrc CSR_STATUS, t6
 	li	a0, 0
 	ret
+
+	/* Exception fixup code */
+10:
+	/* Disable access to user memory */
+	csrs CSR_STATUS, t6
+	mv a0, t5
+	ret
 ENDPROC(__asm_copy_to_user)
 ENDPROC(__asm_copy_from_user)
 EXPORT_SYMBOL(__asm_copy_to_user)
@@ -218,19 +225,12 @@  ENTRY(__clear_user)
 	addi a0, a0, 1
 	bltu a0, a3, 5b
 	j 3b
-ENDPROC(__clear_user)
-EXPORT_SYMBOL(__clear_user)
 
-	.section .fixup,"ax"
-	.balign 4
-	/* Fixup code for __copy_user(10) and __clear_user(11) */
-10:
-	/* Disable access to user memory */
-	csrs CSR_STATUS, t6
-	mv a0, t5
-	ret
+	/* Exception fixup code */
 11:
+	/* Disable access to user memory */
 	csrs CSR_STATUS, t6
 	mv a0, a1
 	ret
-	.previous
+ENDPROC(__clear_user)
+EXPORT_SYMBOL(__clear_user)

[07/12] riscv: lib: uaccess: fold fixups into body

Commit Message

Patch