linux-kernel - [PATCH V2 01/21] riscv: move sbi_init() earlier before jump_label

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Message-Id: <20230216182043.1946553-2-sunilvl@ventanamicro.com>
Date:   Thu, 16 Feb 2023 23:50:23 +0530
From:   Sunil V L <sunilvl@...tanamicro.com>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, Jonathan Corbet <corbet@....net>
Cc:     linux-riscv@...ts.infradead.org, linux-acpi@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Conor Dooley <conor.dooley@...rochip.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Anup Patel <apatel@...tanamicro.com>,
        Atish Patra <atishp@...osinc.com>,
        Jisheng Zhang <jszhang@...nel.org>,
        Anup Patel <anup@...infault.org>
Subject: [PATCH V2 01/21] riscv: move sbi_init() earlier before jump_label_init()

From: Jisheng Zhang <jszhang@...nel.org>

We call jump_label_init() in setup_arch() is to use static key
mechanism earlier, but riscv jump label relies on the sbi functions,
If we enable static key before sbi_init(), the code path looks like:
  static_branch_enable()
    ..
      arch_jump_label_transform()
        patch_text_nosync()
          flush_icache_range()
            flush_icache_all()
              sbi_remote_fence_i() for CONFIG_RISCV_SBI case
                __sbi_rfence()

Since sbi isn't initialized, so NULL deference! Here is a typical
panic log:

[    0.000000] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
[    0.000000] Oops [#1]
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.18.0-rc7+ #79
[    0.000000] Hardware name: riscv-virtio,qemu (DT)
[    0.000000] epc : 0x0
[    0.000000]  ra : sbi_remote_fence_i+0x1e/0x26
[    0.000000] epc : 0000000000000000 ra : ffffffff80005826 sp : ffffffff80c03d50
[    0.000000]  gp : ffffffff80ca6178 tp : ffffffff80c0ad80 t0 : 6200000000000000
[    0.000000]  t1 : 0000000000000000 t2 : 62203a6b746e6972 s0 : ffffffff80c03d60
[    0.000000]  s1 : ffffffff80001af6 a0 : 0000000000000000 a1 : 0000000000000000
[    0.000000]  a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000
[    0.000000]  a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000000080200
[    0.000000]  s2 : ffffffff808b3e48 s3 : ffffffff808bf698 s4 : ffffffff80cb2818
[    0.000000]  s5 : 0000000000000001 s6 : ffffffff80c9c345 s7 : ffffffff80895aa0
[    0.000000]  s8 : 0000000000000001 s9 : 000000000000007f s10: 0000000000000000
[    0.000000]  s11: 0000000000000000 t3 : ffffffff80824d08 t4 : 0000000000000022
[    0.000000]  t5 : 000000000000003d t6 : 0000000000000000
[    0.000000] status: 0000000000000100 badaddr: 0000000000000000 cause: 000000000000000c
[    0.000000] ---[ end trace 0000000000000000 ]---
[    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! ]---

Fix this issue by moving sbi_init() earlier before jump_label_init()

Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
Reviewed-by: Anup Patel <anup@...infault.org>
Reviewed-by: Atish Patra <atishp@...osinc.com>
---
 arch/riscv/kernel/setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 86acd690d529..4335f08ffaf2 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -270,6 +270,7 @@ void __init setup_arch(char **cmdline_p)
 	*cmdline_p = boot_command_line;
 
 	early_ioremap_setup();
+	sbi_init();
 	jump_label_init();
 	parse_early_param();
 
@@ -287,7 +288,6 @@ void __init setup_arch(char **cmdline_p)
 	misc_mem_init();
 
 	init_resources();
-	sbi_init();
 
 #ifdef CONFIG_KASAN
 	kasan_init();
-- 
2.34.1