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From:   Andreas Oetken <ennoerlangen@googlemail.com>
To:     Ley Foon Tan <ley.foon.tan@intel.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        linux-kernel@vger.kernel.org
Cc:     Andreas Oetken <ennoerlangen@gmail.com>,
        Andreas Oetken <andreas.oetken@siemens.com>
Subject: [PATCH] nios2: fixed broken sys_clone syscall
Date:   Fri,  5 Feb 2021 09:23:38 +0100
Message-Id: <20210205082338.584931-1-ennoerlangen@gmail.com>
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From: Andreas Oetken <andreas.oetken@siemens.com>

The tls pointer must be pushed on the stack prior to calling nios2_clone
as it is the 5th function argument. Prior handling of the tls pointer was
done inside former called function copy_thread_tls using the r8 register
from the current_pt_regs directly. This was a bad design and resulted in
the current bug introduced in 04bd52fb.

Fixes: 04bd52fb ("nios2: enable HAVE_COPY_THREAD_TLS, switch to kernel_clone_args")
Signed-off-by: Andreas Oetken <andreas.oetken@siemens.com>
---
 arch/nios2/kernel/entry.S | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/nios2/kernel/entry.S b/arch/nios2/kernel/entry.S
index da8442450e46..0794cd7803df 100644
--- a/arch/nios2/kernel/entry.S
+++ b/arch/nios2/kernel/entry.S
@@ -389,7 +389,10 @@ ENTRY(ret_from_interrupt)
  */
 ENTRY(sys_clone)
 	SAVE_SWITCH_STACK
+	subi    sp, sp, 4 /* make space for tls pointer */
+	stw     r8, 0(sp) /* pass tls pointer (r8) via stack (5th argument) */
 	call	nios2_clone
+	addi    sp, sp, 4
 	RESTORE_SWITCH_STACK
 	ret
 
-- 
2.30.0