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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>,
	"Björn Töpel" <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
Date: Thu, 18 Nov 2021 19:25:14 +0800	[thread overview]
Message-ID: <20211118192514.13d3e873@xhacker> (raw)
In-Reply-To: <20211118192130.48b8f04c@xhacker>

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)
-- 
2.33.0



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WARNING: multiple messages have this Message-ID
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>,
	"Björn Töpel" <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
Date: Thu, 18 Nov 2021 19:25:14 +0800	[thread overview]
Message-ID: <20211118192514.13d3e873@xhacker> (raw)
In-Reply-To: <20211118192130.48b8f04c@xhacker>

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)
-- 
2.33.0



  parent reply	other threads:[~2021-11-18 11:35 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-18 11:21 [PATCH v4 0/12] riscv: switch to relative extable and other improvements Jisheng Zhang
2021-11-18 11:21 ` Jisheng Zhang
2021-11-18 11:22 ` [PATCH 01/12] riscv: remove unused __cmpxchg_user() macro Jisheng Zhang
2021-11-18 11:22   ` Jisheng Zhang
2021-11-18 11:22 ` [PATCH 02/12] riscv: consolidate __ex_table construction Jisheng Zhang
2021-11-18 11:22   ` Jisheng Zhang
2021-11-18 11:22 ` [PATCH 03/12] riscv: switch to relative exception tables Jisheng Zhang
2021-11-18 11:22   ` Jisheng Zhang
2021-11-19  2:09   ` tongtiangen
2021-11-19  2:09     ` tongtiangen
2021-11-18 11:23 ` [PATCH 04/12] riscv: bpf: move rv_bpf_fixup_exception signature to extable.h Jisheng Zhang
2021-11-18 11:23   ` Jisheng Zhang
2021-11-18 11:24 ` [PATCH 05/12] riscv: extable: make fixup_exception() return bool Jisheng Zhang
2021-11-18 11:24   ` Jisheng Zhang
2021-11-18 11:24 ` [PATCH 06/12] riscv: extable: use `ex` for `exception_table_entry` Jisheng Zhang
2021-11-18 11:24   ` Jisheng Zhang
2021-11-18 11:25 ` Jisheng Zhang [this message]
2021-11-18 11:25   ` [PATCH 07/12] riscv: lib: uaccess: fold fixups into body Jisheng Zhang
2021-11-18 11:25 ` [PATCH 08/12] riscv: extable: consolidate definitions Jisheng Zhang
2021-11-18 11:25   ` Jisheng Zhang
2021-11-18 11:26 ` [PATCH 09/12] riscv: extable: add `type` and `data` fields Jisheng Zhang
2021-11-18 11:26   ` Jisheng Zhang
2021-11-18 11:42   ` Jisheng Zhang
2021-11-18 11:42     ` Jisheng Zhang
2021-11-18 15:21     ` Mark Rutland
2021-11-18 15:21       ` Mark Rutland
2022-01-06  3:21       ` Palmer Dabbelt
2022-01-06  3:21         ` Palmer Dabbelt
2022-01-06 10:23         ` Mark Rutland
2022-01-06 10:23           ` Mark Rutland
2021-11-19  2:35   ` tongtiangen
2021-11-19  2:35     ` tongtiangen
2021-11-18 11:26 ` [PATCH 10/12] riscv: add gpr-num.h Jisheng Zhang
2021-11-18 11:26   ` Jisheng Zhang
2021-11-18 11:26 ` [PATCH 11/12] riscv: extable: add a dedicated uaccess handler Jisheng Zhang
2021-11-18 11:26   ` Jisheng Zhang
2022-01-20 18:15   ` Mayuresh Chitale
2022-01-20 18:15     ` Mayuresh Chitale
2022-01-21 12:16     ` Jisheng Zhang
2022-01-21 12:16       ` Jisheng Zhang
2022-01-23  9:12       ` Jisheng Zhang
2022-01-23  9:12         ` Jisheng Zhang
2022-01-24 17:02         ` Mayuresh Chitale
2022-01-24 17:02           ` Mayuresh Chitale
2021-11-18 11:27 ` [PATCH 12/12] riscv: vmlinux.lds.S|vmlinux-xip.lds.S: remove `.fixup` section Jisheng Zhang
2021-11-18 11:27   ` Jisheng Zhang

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