If watchdog is enabled, the arch/powerpc/lib/ticks.S::wait_ticks() function calls the function specified by the WATCHDOG_RESET macro. The wait_ticks function depends on the registers r0, r6 and r7 being preserved however that is not guaranteed, e.g. if the reset function is a C function this will probably overwrite r0 and cause an endless loop.
The following patch changes to using r14+r15 instead of r6+r7 (to resemble what would have been generated by a C compiler) and saves all necessary registers on the stack.
The patch has been tested on a custom MPC5125 based machine using the 512x powerpc architecture.
Signed-off-by: Mats Karrman mats.karrman@tritech.se Cc: Wolfgang Denk wd@denx.de Acked-by: Joakim Tjernlund joakim.tjernlund@transmode.se --- arch/powerpc/lib/ticks.S | 17 +++++++++++------ 1 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/lib/ticks.S b/arch/powerpc/lib/ticks.S index 1781039..63114bb 100644 --- a/arch/powerpc/lib/ticks.S +++ b/arch/powerpc/lib/ticks.S @@ -50,19 +50,24 @@ wait_ticks: stwu r1, -16(r1) mflr r0 /* save link register */ stw r0, 20(r1) /* Use r0 or GDB will be unhappy */ - mr r7, r3 /* save tick count */ + stw r14, 12(r1) /* save used registers */ + stw r15, 8(r1) + mr r14, r3 /* save tick count */ bl get_ticks /* Get start time */
/* Calculate end time */ - addc r7, r4, r7 /* Compute end time lower */ - addze r6, r3 /* and end time upper */ + addc r14, r4, r14 /* Compute end time lower */ + addze r15, r3 /* and end time upper */
WATCHDOG_RESET /* Trigger watchdog, if needed */ 1: bl get_ticks /* Get current time */ - subfc r4, r4, r7 /* Subtract current time from end time */ - subfe. r3, r3, r6 + subfc r4, r4, r14 /* Subtract current time from end time */ + subfe. r3, r3, r15 bge 1b /* Loop until time expired */
- mtlr r0 /* restore link register */ + lwz r15, 8(r1) /* restore saved registers */ + lwz r14, 12(r1) + lwz r0, 20(r1) addi r1,r1,16 + mtlr r0 blr