pussuw commented on a change in pull request #5782:
URL: https://github.com/apache/incubator-nuttx/pull/5782#discussion_r838152965
##########
File path: arch/risc-v/src/common/riscv_swint.c
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@@ -179,6 +187,31 @@ int riscv_swint(int irq, void *context, void *arg)
riscv_registerdump(regs);
#endif
+ /* Handle the syscall */
+
+ regs = riscv_handle_syscall(regs);
+
+ /* Report what happened. That might difficult in the case of a context
+ * switch
+ */
+
+#ifdef CONFIG_DEBUG_SYSCALL_INFO
+ if (regs != CURRENT_REGS)
+ {
+ svcinfo("SWInt Return: Context switch!\n");
+ riscv_registerdump((const uintptr_t *)CURRENT_REGS);
+ }
+ else
+ {
+ svcinfo("SWInt Return: %d\n", regs[REG_A0]);
+ }
+#endif
+
+ return OK;
+}
+
+void *riscv_handle_syscall(uintptr_t *regs)
Review comment:
Good morning, I took a look at riscv_swint.c and the context switch
routines are all dependend on the CURRENT_REGS variable, which is defined as:
`#define CURRENT_REGS (g_current_regs[up_cpu_index()])`
It is a global variable that is dependent on the CPU index too. So no, the
function is not truly re-entrant. I guess what CURRENT_REGS is needed for is to
pass a reference to the modified context to the interrupt return logic, which
is not used when using the trampoline to dispatch a syscall.
As riscv_swint can be entered both from the trampoline as well as interrupt,
the value of CURRENT_REGS really needs to be set and cleared.
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