Messages in this thread Patch in this message | | | From | Heiko Stuebner <> | Subject | [PATCH v8 01/14] riscv: prevent null-pointer dereference with sbi_remote_fence_i | Date | Thu, 24 Mar 2022 01:06:57 +0100 |
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The callback used inside sbi_remote_fence_i is set at sbi probe time to the needed variant. Before that it is a NULL pointer.
Some users like the flush_icache_*() functions suggest a generic functionality, that doesn't depend on a specific boot-stage but uses sbi_remote_fence_i as one option to flush other cpu cores.
So they definitely shouldn't run into null-pointer dereference issues when called "too early" during boot.
So introduce an empty function to be the standard for the __sbi_rfence function pointer until sbi_init has run.
Users of sbi_remote_fence_i will have separate code for the local cpu and sbi_init() is called before other cpus are brought up. So there are no other cpus present at the time when the issue might happen.
Signed-off-by: Heiko Stuebner <heiko@sntech.de> Reviewed-by: Atish Patra <atishp@rivosinc.com> --- arch/riscv/kernel/sbi.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c index 775d3322b422..5a60a458c0b7 100644 --- a/arch/riscv/kernel/sbi.c +++ b/arch/riscv/kernel/sbi.c @@ -16,11 +16,19 @@ unsigned long sbi_spec_version __ro_after_init = SBI_SPEC_VERSION_DEFAULT; EXPORT_SYMBOL(sbi_spec_version); +static int __sbi_rfence_none(int fid, const struct cpumask *cpu_mask, + unsigned long start, unsigned long size, + unsigned long arg4, unsigned long arg5) +{ + return -EOPNOTSUPP; +} + static void (*__sbi_set_timer)(uint64_t stime) __ro_after_init; static int (*__sbi_send_ipi)(const struct cpumask *cpu_mask) __ro_after_init; static int (*__sbi_rfence)(int fid, const struct cpumask *cpu_mask, unsigned long start, unsigned long size, - unsigned long arg4, unsigned long arg5) __ro_after_init; + unsigned long arg4, unsigned long arg5) + __ro_after_init = __sbi_rfence_none; struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0, unsigned long arg1, unsigned long arg2, -- 2.35.1
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