bsps/powerpc: Add PPC_EXC_CONFIG_BOOKE_ONLY

In combination with the PPC_EXC_CONFIG_USE_FIXED_HANDLER option this
removes all dependencies on valid read-write data.  The exception
handling must be statically configured and all components reside in
read-only sections.

c/src/lib/libbsp/powerpc/shared/src/ppc-exc-handler-table.c

@@ -16,12 +16,14 @@
 
 #ifdef PPC_EXC_CONFIG_USE_FIXED_HANDLER
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
 static int ppc_exc_interrupt_dispatch(BSP_Exception_frame *f, unsigned vector)
 {
   bsp_interrupt_dispatch();
 
   return 0;
 }
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
 
 const ppc_exc_handler_t ppc_exc_handler_table [LAST_VALID_EXC + 1] = {
   ppc_exc_handler_default,
@@ -29,7 +31,11 @@ const ppc_exc_handler_t ppc_exc_handler_table [LAST_VALID_EXC + 1] = {
   ppc_exc_handler_default,
   ppc_exc_handler_default,
   ppc_exc_handler_default,
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
   ppc_exc_interrupt_dispatch,
+#else /* PPC_EXC_CONFIG_BOOKE_ONLY */
+  ppc_exc_handler_default,
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
   ppc_exc_handler_default,
   ppc_exc_handler_default,
   ppc_exc_handler_default,

c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_asm_macros.h

@@ -279,6 +279,8 @@ TEST_LOCK_crit_done_\_FLVR:
 /* Standard*/
 	.macro	RECOVER_CHECK_std _FLVR
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 	/* Check if exception is recoverable */
 	lwz	SCRATCH_REGISTER_0, SRR1_FRAME_OFFSET(FRAME_REGISTER)
 	lwz	SCRATCH_REGISTER_1, ppc_exc_msr_bits@sdarel(r13)
@@ -290,6 +292,8 @@ recover_check_twiddle_std_\_FLVR:
 	/* Not recoverable? */
 	bne	recover_check_twiddle_std_\_FLVR
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 	.endm
 
 /* Critical */
@@ -302,6 +306,8 @@ recover_check_twiddle_std_\_FLVR:
 /* Machine check */
 	.macro	RECOVER_CHECK_mchk _FLVR
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 	/* Check if exception is recoverable */
 	lwz	SCRATCH_REGISTER_0, SRR1_FRAME_OFFSET(FRAME_REGISTER)
 	lwz	SCRATCH_REGISTER_1, ppc_exc_msr_bits@sdarel(r13)
@@ -313,6 +319,8 @@ recover_check_twiddle_mchk_\_FLVR:
 	/* Not recoverable? */
 	bne	recover_check_twiddle_mchk_\_FLVR
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 	.endm
 
 /*
@@ -520,6 +528,8 @@ wrap_disable_thread_dispatching_done_\_FLVR:
 	/* Save vector number and exception type */
 	stw	VECTOR_REGISTER, EXCEPTION_NUMBER_OFFSET(FRAME_REGISTER)
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 	/* Load MSR bit mask */
 	lwz	SCRATCH_REGISTER_0, ppc_exc_msr_bits@sdarel(r13)
 
@@ -532,6 +542,8 @@ wrap_disable_thread_dispatching_done_\_FLVR:
 
 wrap_change_msr_done_\_FLVR:
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 #ifdef __ALTIVEC__
 	LA  SCRATCH_REGISTER_0, _CPU_save_altivec_volatile
 	mtctr SCRATCH_REGISTER_0
@@ -660,11 +672,15 @@ wrap_thread_dispatching_done_\_FLVR:
 	bctrl
 #endif
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 	/* Restore MSR? */
 	bne	CR_MSR, wrap_restore_msr_\_FLVR
 
 wrap_restore_msr_done_\_FLVR:
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 	/*
 	 * At this point r1 is a valid exception frame pointer and
 	 * FRAME_REGISTER is no longer needed.
@@ -725,6 +741,8 @@ wrap_restore_msr_done_\_FLVR:
 	/* Return */
 	\_RFI
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 wrap_change_msr_\_FLVR:
 
 	mfmsr	SCRATCH_REGISTER_1
@@ -744,6 +762,8 @@ wrap_restore_msr_\_FLVR:
 	isync
 	b	wrap_restore_msr_done_\_FLVR
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 wrap_save_non_volatile_regs_\_FLVR:
 
 	/* Load pristine stack pointer */

c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c

@@ -31,6 +31,8 @@ uint32_t ppc_exc_vector_register_std  = 0;
 uint32_t ppc_exc_vector_register_crit = 0;
 uint32_t ppc_exc_vector_register_mchk = 0;
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 /* MSR bits to enable once critical status info is saved and the stack
  * is switched; must be set depending on CPU type
  *
@@ -39,6 +41,8 @@ uint32_t ppc_exc_vector_register_mchk = 0;
  */
 uint32_t ppc_exc_msr_bits = MSR_IR | MSR_DR | MSR_RI;
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 int ppc_exc_handler_default(BSP_Exception_frame *f, unsigned int vector)
 {
   return -1;

c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_initialize.c

@@ -192,6 +192,8 @@ void ppc_exc_initialize(
 
   ppc_interrupt_set_disable_mask(interrupt_disable_mask);
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
   /* Use current MMU / RI settings when running C exception handlers */
   ppc_exc_msr_bits = ppc_machine_state_register() & (MSR_DR | MSR_IR | MSR_RI);
 
@@ -199,7 +201,9 @@ void ppc_exc_initialize(
   /* Need vector unit enabled to save/restore altivec context */
   ppc_exc_msr_bits |= MSR_VE;
 #endif
- 
+
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
   if (ppc_cpu_is_bookE() == PPC_BOOKE_STD || ppc_cpu_is_bookE() == PPC_BOOKE_E500) {
     ppc_exc_initialize_booke();
   }
@@ -221,6 +225,7 @@ void ppc_exc_initialize(
     }
   }
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
   /* If we are on a classic PPC with MSR_DR enabled then
    * assert that the mapping for at least this task's
    * stack is write-back-caching enabled (see README/CAVEATS)
@@ -252,4 +257,5 @@ void ppc_exc_initialize(
     __asm__ volatile ("dcbz 0, %0"::"b" (p));
     /* If we make it thru here then things seem to be OK */
   }
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
 }

c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_naked.S

@@ -76,6 +76,8 @@ ppc_exc_wrap_naked:
 	mflr	SCRATCH_REGISTER_0
 	stw	SCRATCH_REGISTER_0, EXC_LR_OFFSET(r1)
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 	/* Load MSR bit mask */
 	lwz	SCRATCH_REGISTER_0, ppc_exc_msr_bits@sdarel(r13)
 
@@ -88,6 +90,8 @@ ppc_exc_wrap_naked:
 
 wrap_change_msr_done_naked:
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 	/*
 	 * Call high level exception handler
 	 */
@@ -127,11 +131,15 @@ wrap_change_msr_done_naked:
 	mtctr	SCRATCH_REGISTER_0
 	bctrl
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 	/* Restore MSR? */
 	bne	CR_MSR, wrap_restore_msr_naked
 
 wrap_restore_msr_done_naked:
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 	/* Restore XER and CTR */
 	lwz	SCRATCH_REGISTER_0, EXC_XER_OFFSET(r1)
 	lwz	SCRATCH_REGISTER_1, EXC_CTR_OFFSET(r1)
@@ -175,6 +183,8 @@ wrap_restore_msr_done_naked:
 	/* Return */
 	rfi
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 wrap_change_msr_naked:
 
 	mfmsr	SCRATCH_REGISTER_1
@@ -193,3 +203,5 @@ wrap_restore_msr_naked:
 	sync
 	isync
 	b	wrap_restore_msr_done_naked
+
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */

c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/vectors.h

@@ -410,6 +410,8 @@ typedef int (*ppc_exc_handler_t)(BSP_Exception_frame *f, unsigned vector);
  */
 int ppc_exc_handler_default(BSP_Exception_frame *f, unsigned int vector);
 
+#ifndef PPC_EXC_CONFIG_BOOKE_ONLY
+
 /**
  * @brief Bits for MSR update.
  *
@@ -422,6 +424,8 @@ int ppc_exc_handler_default(BSP_Exception_frame *f, unsigned int vector);
  */
 extern uint32_t ppc_exc_msr_bits;
 
+#endif /* PPC_EXC_CONFIG_BOOKE_ONLY */
+
 /**
  * @brief Cache write back check flag.
  *