linux-kernel - [PATCH V2] riscv: compat: Using seperated vdso_maps for compat_vdso

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Message-Id: <20220526003339.2948309-1-guoren@kernel.org>
Date:   Wed, 25 May 2022 20:33:39 -0400
From:   guoren@...nel.org
To:     palmer@...osinc.com, arnd@...db.de, linux@...ck-us.net,
        palmer@...belt.com, heiko@...ech.de
Cc:     linux-riscv@...ts.infradead.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, Guo Ren <guoren@...ux.alibaba.com>,
        Guo Ren <guoren@...nel.org>
Subject: [PATCH V2] riscv: compat: Using seperated vdso_maps for compat_vdso_info

From: Guo Ren <guoren@...ux.alibaba.com>

This is a fixup for vdso implementation which caused musl to
fail.

[   11.600082] Run /sbin/init as init process
[   11.628561] init[1]: unhandled signal 11 code 0x1 at
0x0000000000000000 in libc.so[ffffff8ad39000+a4000]
[   11.629398] CPU: 0 PID: 1 Comm: init Not tainted
5.18.0-rc7-next-20220520 #1
[   11.629462] Hardware name: riscv-virtio,qemu (DT)
[   11.629546] epc : 00ffffff8ada1100 ra : 00ffffff8ada13c8 sp :
00ffffffc58199f0
[   11.629586]  gp : 00ffffff8ad39000 tp : 00ffffff8ade0998 t0 :
ffffffffffffffff
[   11.629598]  t1 : 00ffffffc5819fd0 t2 : 0000000000000000 s0 :
00ffffff8ade0cc0
[   11.629610]  s1 : 00ffffff8ade0cc0 a0 : 0000000000000000 a1 :
00ffffffc5819a00
[   11.629622]  a2 : 0000000000000001 a3 : 000000000000001e a4 :
00ffffffc5819b00
[   11.629634]  a5 : 00ffffffc5819b00 a6 : 0000000000000000 a7 :
0000000000000000
[   11.629645]  s2 : 00ffffff8ade0ac8 s3 : 00ffffff8ade0ec8 s4 :
00ffffff8ade0728
[   11.629656]  s5 : 00ffffff8ade0a90 s6 : 0000000000000000 s7 :
00ffffffc5819e40
[   11.629667]  s8 : 00ffffff8ade0ca0 s9 : 00ffffff8addba50 s10:
0000000000000000
[   11.629678]  s11: 0000000000000000 t3 : 0000000000000002 t4 :
0000000000000001
[   11.629688]  t5 : 0000000000020000 t6 : ffffffffffffffff
[   11.629699] status: 0000000000004020 badaddr: 0000000000000000
cause: 000000000000000d

The last __vdso_init(&compat_vdso_info) replaces the data in normal
vdso_info. This is an obvious bug.

Reported-by: Guenter Roeck <linux@...ck-us.net>
Tested-by: Guenter Roeck <linux@...ck-us.net>
Tested-by: Heiko Stübner <heiko@...ech.de>
Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Signed-off-by: Guo Ren <guoren@...nel.org>
Cc: Palmer Dabbelt <palmer@...belt.com>
---
Changes in V2:
 - Add Tested-by
 - Rename vvar & vdso in /proc/<pid>/maps.
---
 arch/riscv/kernel/vdso.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
index 50fe4c877603..957f164c9778 100644
--- a/arch/riscv/kernel/vdso.c
+++ b/arch/riscv/kernel/vdso.c
@@ -206,12 +206,23 @@ static struct __vdso_info vdso_info __ro_after_init = {
 };
 
 #ifdef CONFIG_COMPAT
+static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
+	[RV_VDSO_MAP_VVAR] = {
+		.name   = "[compat vvar]",
+		.fault = vvar_fault,
+	},
+	[RV_VDSO_MAP_VDSO] = {
+		.name   = "[compat vdso]",
+		.mremap = vdso_mremap,
+	},
+};
+
 static struct __vdso_info compat_vdso_info __ro_after_init = {
 	.name = "compat_vdso",
 	.vdso_code_start = compat_vdso_start,
 	.vdso_code_end = compat_vdso_end,
-	.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
-	.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
+	.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
+	.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
 };
 #endif
 
-- 
2.36.1