[1/3] arch/xtensa: Provide vfork()

arch/Kconfig

@@ -158,6 +158,7 @@ config ARCH_X86_64
 config ARCH_XTENSA
 	bool "Xtensa"
 	select ARCH_HAVE_BACKTRACE
+	select ARCH_HAVE_VFORK
 	select ARCH_HAVE_CPUINFO
 	select ARCH_HAVE_INTERRUPTSTACK
 	select ARCH_HAVE_STACKCHECK

arch/xtensa/include/irq.h

@@ -217,6 +217,16 @@ struct xcptcontext
   uint32_t *regs;
 
 #ifdef CONFIG_LIB_SYSCALL
+  /* The exception frame of the system call currently in progress, i.e. the
+   * caller's register context as the vector saved it.  A system call body
+   * runs as ordinary C code long after the exception has been dispatched, so
+   * this is the only way for one to reach the registers of the thread that
+   * made the call -- vfork() needs the caller's stack pointer and return
+   * address to give the child a copy.
+   */
+
+  uint32_t *sregs;
+
   /* The following array holds the return address and the exc_return value
    * needed to return from each nested system call.
    */

arch/xtensa/src/common/Make.defs

@@ -39,6 +39,11 @@ CMN_CSRCS += xtensa_modifyreg8.c xtensa_modifyreg16.c xtensa_modifyreg32.c
 CMN_CSRCS += xtensa_mpu.c xtensa_nputs.c xtensa_oneshot.c xtensa_perf.c
 CMN_CSRCS += xtensa_releasestack.c xtensa_registerdump.c
 CMN_CSRCS += xtensa_swint.c xtensa_stackframe.c
+
+ifneq ($(CONFIG_ARCH_HAVE_FORK)$(CONFIG_ARCH_HAVE_VFORK),)
+CMN_CSRCS += xtensa_fork.c
+endif
+
 CMN_CSRCS += xtensa_saveusercontext.c
 CMN_CSRCS += xtensa_usestack.c xtensa_tcbinfo.c