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SubjectRe: [PATCH 04/28] nios2: Exception handling
Hi Ley Foon,

On Apr 18, Ley Foon Tan wrote:
> +
> + /* Get thread info pointer */
> + movi r11, %lo(0xfffff000)
> + and r11, sp, r11
> + ldw r11, TI_FLAGS(r11)
> +
> + /* If someone is ptrace:ing us, take the long way. */
> + BTBNZ r11, r11, TIF_SYSCALL_TRACE, traced_system_call
> +

Are you sure this is correct? Have you tested this works correctly?

Last time I tested this, it caused the traced_system_call to be taken
for every system call. I already reported and provided a patch a few
months ago:

http://lists.rocketboards.org/pipermail/nios2-dev/2014-January/006968.html

Here's my proposed fix:

diff --git a/arch/nios2/kernel/entry.S b/arch/nios2/kernel/entry.S
index 9cf2bac..3798008 100644
--- a/arch/nios2/kernel/entry.S
+++ b/arch/nios2/kernel/entry.S
@@ -204,13 +204,10 @@ ENTRY(handle_system_call)
ldw r1, %lo(sys_call_table)(r1)
beq r1, r0, ret_invsyscall

- /* Get thread info pointer */
- movi r11, %lo(0xfffff000)
- and r11, sp, r11
- ldw r11, TI_FLAGS(r11)
-
- /* If someone is ptrace:ing us, take the long way. */
- BTBNZ r11, r11, TIF_SYSCALL_TRACE, traced_system_call
+ /* Check if we are being traced */
+ GET_THREAD_INFO r11
+ ldw r11,TI_FLAGS(r11)
+ BTBNZ r11,r11,TIF_SYSCALL_TRACE,traced_system_call

/* Execute the system call */
callr r1
--
1.9.1
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com
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