On Mon, Dec 20, 2021 at 5:17 PM Ard Biesheuvel [off-list ref] wrote:

On Mon, 20 Dec 2021 at 10:11, Guo Ren [off-list ref] wrote:

quoted

On Tue, Dec 7, 2021 at 11:55 AM Alexandre Ghiti
[off-list ref] wrote:

quoted

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__?

Don't use __attribute__((optimize())) for that: it is known to be
broken, and documented as debug purposes only in the GCC info pages:

https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html

Oh, thx for the link.

quoted

Actually, we've already init tp later.

quoted

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 <redacted>
---
 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/

-- 
Best Regards
 Guo Ren

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