[mynewt-core] branch master updated: kernel/os: Fix os_arch_in_isr for pic32

[jerzy]

This is an automated email from the ASF dual-hosted git repository.

jerzy pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mynewt-core.git


The following commit(s) were added to refs/heads/master by this push:
     new 79099c7  kernel/os: Fix os_arch_in_isr for pic32
79099c7 is described below

commit 79099c75e1b999e378920e2abb2e1a2aec60986c
Author: Jerzy Kasenberg <je...@apache.org>
AuthorDate: Sat Nov 27 10:01:32 2021 +0100

    kernel/os: Fix os_arch_in_isr for pic32
    
    Code was checking STATUS register EXL bit to check if CPU is in ISR.
    This is true when CPU starts handling interrupt, but normal code
    generated by xc32-gcc turns off this bit in ISR code before
    user code is executed.
    
    void __attribute__((interrupt(IPL3AUTO), vector(_TIMER_2_VECTOR))) 
timer2_isr(void)
    {
    9d008198:   415de800        rdpgpr  sp,sp
    9d00819c:   401b7000        mfc0    k1,c0_epc
    9d0081a0:   401a6002        mfc0    k0,c0_srsctl
    9d0081a4:   27bdfed0        addiu   sp,sp,-304
    9d0081a8:   afbb012c        sw      k1,300(sp)
    9d0081ac:   401b6000        mfc0    k1,c0_status  // k1 has STATUS with EXL 
bit set
    9d0081b0:   afba0124        sw      k0,292(sp)
    9d0081b4:   afbb0128        sw      k1,296(sp)
    9d0081b8:   7c1b7844        ins     k1,zero,0x1,0xf   // k1 has now only IE 
preserved (which is 1 since code is in ISR), EXL is cleared
    9d0081bc:   377b0c00        ori     k1,k1,0xc00       // k1 IPL is set to 3 
(from IPL3AUTO)
    9d0081c0:   409b6000        mtc0    k1,c0_status  // status has now IE 1 
and IPL > 0, EXL is 0 to allow nested interrupts
    
    EXL bit is cleared to allow nested interrupts so to check if code is in 
interrupt
    EXL can be checked but also IPL > 0 indicates that code is in ISR handler
---
 kernel/os/include/os/arch/pic32/os/os_arch.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/os/include/os/arch/pic32/os/os_arch.h 
b/kernel/os/include/os/arch/pic32/os/os_arch.h
index 7b78d61..2584949 100644
--- a/kernel/os/include/os/arch/pic32/os/os_arch.h
+++ b/kernel/os/include/os/arch/pic32/os/os_arch.h
@@ -46,8 +46,8 @@ typedef uint32_t os_stack_t;
 static inline int
 os_arch_in_isr(void)
 {
-    /* check the EXL bit */
-    return (_CP0_GET_STATUS() & _CP0_STATUS_EXL_MASK) ? 1 : 0;
+    /* CPU handles interrupt when EXL is set or IPL > 0 */
+    return (_CP0_GET_STATUS() & (_CP0_STATUS_EXL_MASK | _CP0_STATUS_IPL_MASK)) 
? 1 : 0;
 }
 
 /* Include common arch definitions and APIs */