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authorMats Kärrman <mats.karrman@tritech.se>2013-04-09 17:10:59 +0200
committerTom Rini <trini@ti.com>2013-04-10 10:31:02 -0400
commitfac150e83f403933e9ffc9d01f858c4a6313874e (patch)
treebb4ba2875fd12abdc370040eb79af5f1125407be /arch/powerpc
parent645b271a6039e79b368f027a5624dc0820441733 (diff)
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powerpc/lib: fix unsafe register handling in wait_ticks
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> Tested-by: Stefan Roese <sr@denx.de>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/lib/ticks.S17
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