[PATCH 1/6] OpenRISC: Account for red-zone (fixup printf bug).
Hesham ALMatary
heshamelmatary at gmail.com
Mon Sep 15 22:33:28 UTC 2014
This patch allocate a space in the stack to account for red-zone
that gcc may utilize for the use of leaf functions. Care must be
taken to handle this red-zone from many places:
1- Upon creation of a new thread stack.
2- Once an interrupt entred.
Also moving the enable-thread-dispach() and increment ISR level before
checking if dispatch needed was required.
The previous modifications solved the printf bug which disabled ticker
to output strings after context switches that arise from Thread_Delay_ended.
---
c/src/lib/libbsp/or1k/or1ksim/start/start.S | 2 +-
cpukit/score/cpu/or1k/or1k-context-initialize.c | 3 +-
cpukit/score/cpu/or1k/or1k-exception-handler-low.S | 42 +++++++++++-----------
3 files changed, 25 insertions(+), 22 deletions(-)
diff --git a/c/src/lib/libbsp/or1k/or1ksim/start/start.S b/c/src/lib/libbsp/or1k/or1ksim/start/start.S
index 6942b52..4d911d4 100644
--- a/c/src/lib/libbsp/or1k/or1ksim/start/start.S
+++ b/c/src/lib/libbsp/or1k/or1ksim/start/start.S
@@ -16,7 +16,7 @@
*/
#define EXCEPTION_SETUP(vector) \
l.nop ;\
- l.addi r1, r1, -4 ;\
+ l.addi r1, r1, -200 ;\
l.sw 0(r1), r3; \
l.addi r3, r0, vector; \
l.j _ISR_Handler; \
diff --git a/cpukit/score/cpu/or1k/or1k-context-initialize.c b/cpukit/score/cpu/or1k/or1k-context-initialize.c
index 7ac2875..1c9cdd7 100644
--- a/cpukit/score/cpu/or1k/or1k-context-initialize.c
+++ b/cpukit/score/cpu/or1k/or1k-context-initialize.c
@@ -29,7 +29,8 @@ void _CPU_Context_Initialize(
void *tls_area
)
{
- uint32_t stack = (uint32_t) stack_area_begin;
+ /* Decrement 200 byte to account for red-zone */
+ uint32_t stack = ((uint32_t) stack_area_begin) - 200;
uint32_t sr;
sr = _OR1K_mfspr(CPU_OR1K_SPR_SR);
diff --git a/cpukit/score/cpu/or1k/or1k-exception-handler-low.S b/cpukit/score/cpu/or1k/or1k-exception-handler-low.S
index 7108ff6..b18c4a3 100644
--- a/cpukit/score/cpu/or1k/or1k-exception-handler-low.S
+++ b/cpukit/score/cpu/or1k/or1k-exception-handler-low.S
@@ -93,7 +93,7 @@ PUBLIC(_ISR_Handler)
l.sw 0(r8), r7
/* Save interrupted task stack pointer */
- l.addi r4, r1, 144
+ l.addi r4, r1, 340
l.sw 4(r1), r4
/* Save interrupted task r3 (first arg) value */
@@ -118,7 +118,7 @@ PUBLIC(_ISR_Handler)
/* Do not switch stacks if we are in a nested interrupt. At
* this point r5 should be holding ISR_NEST_LEVEL value.
*/
- l.sfgtui r5, 2
+ l.sfgtui r5, 1
l.bf jump_to_c_handler
l.nop
@@ -134,6 +134,21 @@ jump_to_c_handler:
/* Switch back to the interrupted task stack */
l.add r1, r14, r0
+ /* Decrement nesting level */
+ l.movhi r6, hi(ISR_NEST_LEVEL)
+ l.ori r6, r6, lo(ISR_NEST_LEVEL)
+
+ /* Enable multitasking */
+ l.movhi r8, hi(THREAD_DISPATCH_DISABLE_LEVEL)
+ l.ori r8, r8, lo(THREAD_DISPATCH_DISABLE_LEVEL)
+
+ l.lwz r5, 0(r6)
+ l.lwz r7, 0(r8)
+ l.addi r5, r5, -1
+ l.addi r7, r7, -1
+ l.sw 0(r6), r5
+ l.sw 0(r8), r7
+
/* Check if dispatch needed */
l.movhi r31, hi(DISPATCH_NEEDED)
l.ori r31, r31, lo(DISPATCH_NEEDED)
@@ -163,21 +178,6 @@ jump_to_c_handler:
l.lwz r13, 136(r1)
l.mtspr r0, r13, CPU_OR1K_SPR_ESR0
- /* Increment nesting level */
- l.movhi r6, hi(ISR_NEST_LEVEL)
- l.ori r6, r6, lo(ISR_NEST_LEVEL)
-
- /* Disable multitasking */
- l.movhi r8, hi(THREAD_DISPATCH_DISABLE_LEVEL)
- l.ori r8, r8, lo(THREAD_DISPATCH_DISABLE_LEVEL)
-
- l.lwz r5, 0(r6)
- l.lwz r7, 0(r8)
- l.addi r5, r5, -1
- l.addi r7, r7, -1
- l.sw 0(r6), r5
- l.sw 0(r8), r7
-
l.lwz r2, 8(r1)
l.lwz r3, 12(r1)
l.lwz r4, 16(r1)
@@ -208,10 +208,12 @@ jump_to_c_handler:
l.lwz r29, 116(r1)
l.lwz r30, 120(r1)
l.lwz r31, 124(r1)
-
+
+ /* Unwind exception frame */
l.addi r1, r1, 140
-
- l.addi r1, r1, 4
+
+ /* Red-zone */
+ l.addi r1, r1, 200
l.rfe
l.nop
--
1.9.3
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