riscv: Initialize thread pointer before calling C functions

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
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@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 273eb0f..b865046 100644 (file)
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -298,6 +298,7 @@ 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