From: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
To: linux-kernel@vger.kernel.org
Cc: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>,
Pierce Andjelkovic <pierceandjelkovic@gmail.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
linux-riscv@lists.infradead.org
Subject: [PATCH] RISC-V: prevent sbi_send_cpumask_ipi race with ftrace
Date: Thu, 12 Aug 2021 13:34:33 +0100 [thread overview]
Message-ID: <20210812123433.27871-1-dimitri.ledkov@canonical.com> (raw)
From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
ftrace will patch instructions in sbi_send_cpumask_ipi, which is going to
be used by flush_icache_range, leading to potential races and crashes like
this:
[ 0.000000] ftrace: allocating 38893 entries in 152 pages
[ 0.000000] Oops - illegal instruction [#1]
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.11.0-1014-generic #14-Ubuntu
[ 0.000000] epc: ffffffe00000920e ra : ffffffe000009384 sp : ffffffe001803d30
[ 0.000000] gp : ffffffe001a14240 tp : ffffffe00180f440 t0 : ffffffe07fe38000
[ 0.000000] t1 : ffffffe0019cd338 t2 : 0000000000000000 s0 : ffffffe001803d70
[ 0.000000] s1 : 0000000000000000 a0 : ffffffe0000095aa a1 : 0000000000000001
[ 0.000000] a2 : 0000000000000002 a3 : 0000000000000000 a4 : 0000000000000000
[ 0.000000] a5 : 0000000000000000 a6 : 0000000000000004 a7 : 0000000052464e43
[ 0.000000] s2 : 0000000000000002 s3 : 0000000000000001 s4 : 0000000000000000
[ 0.000000] s5 : 0000000000000000 s6 : 0000000000000000 s7 : 0000000000000000
[ 0.000000] s8 : ffffffe001a170c0 s9 : 0000000000000001 s10: 0000000000000001
[ 0.000000] s11: 00000000fffcc5d0 t3 : 0000000000000068 t4 : 000000000000000b
[ 0.000000] t5 : ffffffe0019cd3e0 t6 : ffffffe001803cd8
[ 0.000000] status: 0000000200000100 badaddr: 000000000513f187 cause: 0000000000000002
[ 0.000000] ---[ end trace f67eb9af4d8d492b ]---
[ 0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
[ 0.000000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---
Where ffffffe00000920e lies in the middle of sbi_send_cpumask_ipi.
Reproduced on Unmatched board using Ubuntu kernels. See
https://people.canonical.com/~xnox/lp1934548/ for sample images,
kernels, debug symbols.
BugLink: https://bugs.launchpad.net/bugs/1934548
Reported-by: Pierce Andjelkovic <pierceandjelkovic@gmail.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
cc: Paul Walmsley <paul.walmsley@sifive.com>
cc: linux-riscv@lists.infradead.org
cc: stable@vger.kernel.org
---
arch/riscv/kernel/sbi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 7402a417f38e..158199865c68 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -562,7 +562,7 @@ long sbi_get_mimpid(void)
return __sbi_base_ecall(SBI_EXT_BASE_GET_MIMPID);
}
-static void sbi_send_cpumask_ipi(const struct cpumask *target)
+static void notrace sbi_send_cpumask_ipi(const struct cpumask *target)
{
struct cpumask hartid_mask;
--
2.30.2
next reply other threads:[~2021-08-12 12:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-12 12:34 Dimitri John Ledkov [this message]
2021-08-12 15:53 ` [PATCH] RISC-V: prevent sbi_send_cpumask_ipi race with ftrace Atish Patra
2021-08-13 17:09 ` Dimitri John Ledkov
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