riscv: initialize jump labels before early_init_dt_scan()

[PATCH] riscv: initialize jump labels before early_init_dt_scan()

Posted by Jason A. Donenfeld 3 years, 10 months ago

Stephen reported that a static key warning splat appears during early
boot on arm64 systems that credit randomness from device trees that
contain an "rng-seed" property, because the dtb is parsed is called
before jump_label_init() during setup_arch(), which was fixed by
73e2d827a501 ("arm64: Initialize jump labels before
setup_machine_fdt()").

The same basic issue applies to RISC-V as well. So this commit moves the
call to jump_label_init() just before early_init_dt_scan().
jump_label_init() actually requires sbi_init() to be called first for
proper functioning, so it also moves that to the right place.

Reported-by: Stephen Boyd <swboyd@chromium.org>
Reported-by: Phil Elwell <phil@raspberrypi.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Fixes: f5bda35fba61 ("random: use static branch for crng_ready()")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/riscv/kernel/setup.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index f0f36a4a0e9b..c44c81b1cfb3 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -263,13 +263,15 @@ static void __init parse_dtb(void)
 
 void __init setup_arch(char **cmdline_p)
 {
+	early_ioremap_setup();
+	sbi_init();
+	jump_label_init();
+
 	parse_dtb();
 	setup_initial_init_mm(_stext, _etext, _edata, _end);
 
 	*cmdline_p = boot_command_line;
 
-	early_ioremap_setup();
-	jump_label_init();
 	parse_early_param();
 
 	efi_init();
@@ -285,7 +287,6 @@ void __init setup_arch(char **cmdline_p)
 	misc_mem_init();
 
 	init_resources();
-	sbi_init();
 
 #ifdef CONFIG_KASAN
 	kasan_init();
-- 
2.35.1

Re: [PATCH] riscv: initialize jump labels before early_init_dt_scan()

Posted by Jisheng Zhang 3 years, 10 months ago

On Tue, Jun 07, 2022 at 09:57:52PM +0200, Jason A. Donenfeld wrote:
> Stephen reported that a static key warning splat appears during early
> boot on arm64 systems that credit randomness from device trees that
> contain an "rng-seed" property, because the dtb is parsed is called
> before jump_label_init() during setup_arch(), which was fixed by
> 73e2d827a501 ("arm64: Initialize jump labels before
> setup_machine_fdt()").
> 
> The same basic issue applies to RISC-V as well. So this commit moves the

> call to jump_label_init() just before early_init_dt_scan().
> jump_label_init() actually requires sbi_init() to be called first for

Moving the sbi_init() earlier has been sent out but the patch is missing
in 5.19-rc1

https://lore.kernel.org/linux-riscv/20220521143456.2759-1-jszhang@kernel.org/T/#m00c3cb5e4e360ca8d7aa10c79c10437b7307c16c



> proper functioning, so it also moves that to the right place.
> 
> Reported-by: Stephen Boyd <swboyd@chromium.org>
> Reported-by: Phil Elwell <phil@raspberrypi.com>
> Cc: Ard Biesheuvel <ardb@kernel.org>
> Cc: Russel King <linux@armlinux.org.uk>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Fixes: f5bda35fba61 ("random: use static branch for crng_ready()")
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  arch/riscv/kernel/setup.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index f0f36a4a0e9b..c44c81b1cfb3 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -263,13 +263,15 @@ static void __init parse_dtb(void)
>  
>  void __init setup_arch(char **cmdline_p)
>  {
> +	early_ioremap_setup();
> +	sbi_init();
> +	jump_label_init();
> +
>  	parse_dtb();
>  	setup_initial_init_mm(_stext, _etext, _edata, _end);
>  
>  	*cmdline_p = boot_command_line;
>  
> -	early_ioremap_setup();
> -	jump_label_init();
>  	parse_early_param();
>  
>  	efi_init();
> @@ -285,7 +287,6 @@ void __init setup_arch(char **cmdline_p)
>  	misc_mem_init();
>  
>  	init_resources();
> -	sbi_init();
>  
>  #ifdef CONFIG_KASAN
>  	kasan_init();
> -- 
> 2.35.1
> 
> 
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> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

Re: [PATCH] riscv: initialize jump labels before early_init_dt_scan()

Posted by Jason A. Donenfeld 3 years, 10 months ago

This patch isn't needed in the end. An equivalent patch is needed on
xtensa, powerpc, arc, mips, arm32, arm64, riscv. That's a bit much and
points to a larger issue. So I'll fix this the ugly way in the
random.c code :(.

H o w e v e r, I'm pretty sure that you do need to move the sbi_init()
call above the existing jump_label_init() call as already existing. So
you might consider doing that.

Jason