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xtensa: Fix thread entry point

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The stack initilaization was calling the user-provided entry function
directly, which works fine until that function returns, at which point
it will try to unspill A0-A3 from the 16 bytes above the allocated
stack and then "return" to a NULL pointer.

The kernel provides a _thread_entry() function that does cleanup
properly, so use that.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2017-12-17 09:30:39 -08:00 • committed by Anas Nashif
commit 63ad74f833
1 changed files with 14 additions and 13 deletions
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27
arch/xtensa/core/xtensa-asm2.c
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@ -9,6 +9,7 @@
#include <kernel.h>
#include <ksched.h>
#include <kernel_structs.h>
#include <nano_internal.h>
#include <_soc_inthandlers.h>
void *xtensa_init_stack(int *stack_top,
@ -27,23 +28,23 @@ void *xtensa_init_stack(int *stack_top,
memset(bsa, 0, bsasz);
bsa[BSA_PC_OFF/4] = entry;
bsa[BSA_PC_OFF/4] = _thread_entry;
bsa[BSA_PS_OFF/4] = (void *)(PS_WOE | PS_UM | PS_CALLINC(1));
/* Arguments. Remember these start at A6, which will be
* rotated into A2 by the ENTRY instruction that begins the
* entry function. And A4-A7 and A8-A11 are optional quads
* that live below the BSA!
/* Arguments to _thread_entry(). Remember these start at A6,
* which will be rotated into A2 by the ENTRY instruction that
* begins the C function. And A4-A7 and A8-A11 are optional
* quads that live below the BSA!
*/
bsa[-1] = arg2; /* a7 */
bsa[-2] = arg1; /* a6 */
bsa[-3] = 0; /* a5 */
bsa[-4] = 0; /* a4 */
bsa[-1] = arg1; /* a7 */
bsa[-2] = entry; /* a6 */
bsa[-3] = 0; /* a5 */
bsa[-4] = 0; /* a4 */
bsa[-5] = 0; /* a11 */
bsa[-6] = 0; /* a10 */
bsa[-7] = 0; /* a9 */
bsa[-8] = arg3; /* a8 */
bsa[-5] = 0; /* a11 */
bsa[-6] = 0; /* a10 */
bsa[-7] = arg3; /* a9 */
bsa[-8] = arg2; /* a8 */
/* Finally push the BSA pointer and return the stack pointer
* as the handle