[PATCH v3 12/13] riscv: Initialize thread pointer before calling C functions

[Guo Ren]

On Tue, Dec 7, 2021 at 11:55 AM Alexandre Ghiti
<alexandre.ghiti at canonical.com> wrote:
>
> Because of the stack canary feature that reads from the current task
> structure the stack canary value, the thread pointer register "tp" must
> be set before calling any C function from head.S: by chance, setup_vm
Shall we disable -fstack-protector for setup_vm() with __attribute__?
Actually, we've already init tp later.

> and all the functions that it calls does not seem to be part of the
> functions where the canary check is done, but in the following commits,
> some functions will.
>
> Fixes: f2c9699f65557a31 ("riscv: Add STACKPROTECTOR supported")
> Signed-off-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>
> ---
>  arch/riscv/kernel/head.S | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> index c3c0ed559770..86f7ee3d210d 100644
> --- a/arch/riscv/kernel/head.S
> +++ b/arch/riscv/kernel/head.S
> @@ -302,6 +302,7 @@ clear_bss_done:
>         REG_S a0, (a2)
>
>         /* Initialize page tables and relocate to virtual addresses */
> +       la tp, init_task
>         la sp, init_thread_union + THREAD_SIZE
>         XIP_FIXUP_OFFSET sp
>  #ifdef CONFIG_BUILTIN_DTB
> --
> 2.32.0
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/