michaelh/zephyr
1
0
Fork 0
Code Releases Activity

arm: use BASEPRI_MAX instead of BASEPRI to mask interrupts

Browse source 
When locking interrupt in a critical session, it is
safer to do MSR BASEPRI_MAX instead of BASEPRI. The
rationale is that when writing to BASEPRI_MAX, the
writing is conditional, and is only applied if the
change is to a higher priority level. This commit
replaces BASEPRI with BASEPRI_MAX in operations that
aim to lock some specific interrupts:
- irq_lock()
- masking out PendSV
So, for example, it is not possible to actually
unmask any interrupts by doing an irq_lock operation.
The commit does not introduce behavioral changes.
However, it makes irq_lock() more robust against
future changes to the IRQ locking mechanism.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
This commit is contained in:
Ioannis Glaropoulos 2021-06-22 11:46:50 +02:00 • committed by Christopher Friedt
commit 03c4bcd920
3 changed files with 4 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

2
include/arch/arm/aarch32/asm_inline_gcc.h
View file

@ -56,7 +56,7 @@ static ALWAYS_INLINE unsigned int arch_irq_lock(void)
__asm__ volatile(
"mov %1, %2;"
"mrs %0, BASEPRI;"
"msr BASEPRI, %1;"
"msr BASEPRI_MAX, %1;"
"isb;"
: "=r"(key), "=r"(tmp)
: "i"(_EXC_IRQ_DEFAULT_PRIO)