x86: improve exception APIs

Previously, exception stubs had to be declared in assembly
language files. Now we have two new APIs to regsiter exception
handlers at C toplevel:

 _EXCEPTION_CONNECT_CODE(handler, vector)
 _EXCEPTION_CONNECT_NOCODE(handler, vector)

For x86 exceptions that do and do not push error codes onto
the stack respectively.

In addition, it's now no longer necessary to #define around
exception registration. We now use .gnu.linkonce magic such that
the first _EXCEPTION_CONNECT_*() that the linker finds is used
for the specified vector. Applications are free to install their
own exception handlers which will take precedence over default
handlers such as installed by arch/x86/core/fatal.c

Some Makefiles have been adjusted so that the default exception
handlers in arch/x86/core/fatal.c are linked last. The code has
been tested that the right order of precedence is taken for
exceptions overridden in the floating point, gdb debug, or
application code. The asm SYS_NANO_CPU_EXC_CONNECT API has been
removed; it was ill- conceived as it only worked for exceptions
that didn't push error codes. All the asm NANO_CPU_EXC_CONNECT_*
APIs are gone as well in favor of the new _EXCEPTION_CONNNECT_*()
APIs.

CONFIG_EXCEPTION_DEBUG no longer needs to be disabled for test
cases that define their own exception handlers.

Issue: ZEP-203
Change-Id: I782e0143fba832d18cdf4daaa7e47820595fe041
Signed-off-by: Andrew Boie <[email protected]>

arch/x86/Kbuild

@@ -1,3 +1,5 @@
-obj-y += core/
 obj-$(CONFIG_GDB_SERVER) += debug/
 obj-y += soc/$(SOC_PATH)/
+# Must be last so that debug/ or soc/ can override default exception
+# handlers
+obj-y += core/

arch/x86/core/Makefile

@@ -11,7 +11,7 @@ endif
 # character starts a comment
 KBUILD_AFLAGS += -Wa,--divide
 
-obj-y += fatal.o cpuhalt.o \
+obj-y += cpuhalt.o \
 	msr.o dynamic.o intconnect.o \
 	excconnect.o sys_fatal_error_handler.o \
 	crt0.o cache_s.o cache.o excstub.o \
@@ -25,3 +25,6 @@ obj-$(CONFIG_REBOOT_RST_CNT) += reboot_rst_cnt.o
 
 obj-$(CONFIG_DEBUG_INFO) += debug/
 obj-$(CONFIG_REBOOT_RST_CNT) += reboot_rst_cnt.o
+
+# Last since we declare default exception handlers here
+obj-y += fatal.o

arch/x86/core/excstub.S

@@ -32,7 +32,6 @@
 #include <offsets.h>	/* nanokernel structure offset definitions */
 
 
-#include <asmPrv.h>
 
 	/* exports (internal APIs) */
 
@@ -298,37 +297,6 @@ BRANCH_LABEL(nestedException)
 	/* Pop of EFLAGS will re-enable interrupts and restore direction flag */
 	iret
 
-	/* Static exception handler stubs */
-#if CONFIG_FP_SHARING
-SYS_NANO_CPU_EXC_CONNECT(_FpNotAvailableExcHandler,IV_DEVICE_NOT_AVAILABLE)
-#endif /* CONFIG_FP_SHARING */
-
-#if CONFIG_EXCEPTION_DEBUG
-
-#define EXC_HANDLER(vec) NANO_CPU_EXC_CONNECT_NO_ERR(handle_exc_##vec, vec, 0)
-#define EXC_HANDLER_CODE(vec) NANO_CPU_EXC_CONNECT(handle_exc_##vec, vec, 0)
-
-#if !defined(CONFIG_DEBUGGER_OWNS_FATAL_PROG_EXC_HANDLERS)
-EXC_HANDLER(IV_DIVIDE_ERROR)
-EXC_HANDLER_CODE(IV_PAGE_FAULT)
-#endif
-
-EXC_HANDLER(IV_NON_MASKABLE_INTERRUPT)
-EXC_HANDLER(IV_OVERFLOW)
-EXC_HANDLER(IV_BOUND_RANGE)
-EXC_HANDLER(IV_INVALID_OPCODE)
-#ifndef CONFIG_FP_SHARING
-EXC_HANDLER(IV_DEVICE_NOT_AVAILABLE)
-#endif
-EXC_HANDLER_CODE(IV_DOUBLE_FAULT)
-EXC_HANDLER_CODE(IV_INVALID_TSS)
-EXC_HANDLER_CODE(IV_SEGMENT_NOT_PRESENT)
-EXC_HANDLER_CODE(IV_STACK_FAULT)
-EXC_HANDLER_CODE(IV_GENERAL_PROTECTION)
-EXC_HANDLER(IV_X87_FPU_FP_ERROR)
-EXC_HANDLER_CODE(IV_ALIGNMENT_CHECK)
-EXC_HANDLER(IV_MACHINE_CHECK)
-#endif /* CONFIG_EXCEPTION_DEBUG */
 
 #if ALL_DYN_EXC_STUBS > 0
 BRANCH_LABEL(_DynExcStubCommon)

arch/x86/core/fatal.c

@@ -27,8 +27,8 @@
 #include <nanokernel.h>
 #include <nano_private.h>
 #include <misc/printk.h>
-#include <asmPrv.h>
 #include <drivers/loapic.h>
+#include <exception.h>
 
 __weak void _debug_fatal_hook(const NANO_ESF *esf) { ARG_UNUSED(esf); }
 
@@ -138,29 +138,44 @@ static FUNC_NORETURN void generic_exc_handle(unsigned int vector,
 	_NanoFatalErrorHandler(_NANO_ERR_CPU_EXCEPTION, pEsf);
 }
 
-#define EXC_FUNC(vector) \
+#define _EXC_FUNC(vector) \
 FUNC_NORETURN void handle_exc_##vector(const NANO_ESF *pEsf) \
 { \
 	generic_exc_handle(vector, pEsf); \
 }
 
-EXC_FUNC(IV_DIVIDE_ERROR);
-EXC_FUNC(IV_NON_MASKABLE_INTERRUPT);
-EXC_FUNC(IV_OVERFLOW);
-EXC_FUNC(IV_BOUND_RANGE);
-EXC_FUNC(IV_INVALID_OPCODE);
-#ifndef CONFIG_FP_SHARING
-EXC_FUNC(IV_DEVICE_NOT_AVAILABLE);
-#endif
-EXC_FUNC(IV_DOUBLE_FAULT);
-EXC_FUNC(IV_INVALID_TSS);
-EXC_FUNC(IV_SEGMENT_NOT_PRESENT);
-EXC_FUNC(IV_STACK_FAULT);
-EXC_FUNC(IV_GENERAL_PROTECTION);
-EXC_FUNC(IV_PAGE_FAULT);
-EXC_FUNC(IV_X87_FPU_FP_ERROR);
-EXC_FUNC(IV_ALIGNMENT_CHECK);
-EXC_FUNC(IV_MACHINE_CHECK);
+#define _EXC_FUNC_CODE(vector) \
+	_EXC_FUNC(vector) \
+	_EXCEPTION_CONNECT_CODE(handle_exc_##vector, vector)
+
+#define _EXC_FUNC_NOCODE(vector) \
+	_EXC_FUNC(vector) \
+	_EXCEPTION_CONNECT_NOCODE(handle_exc_##vector, vector)
+
+/* Necessary indirection to ensure 'vector' is expanded before we expand
+ * the handle_exc_##vector
+ */
+#define EXC_FUNC_NOCODE(vector) \
+	_EXC_FUNC_NOCODE(vector)
+
+#define EXC_FUNC_CODE(vector) \
+	_EXC_FUNC_CODE(vector)
+
+EXC_FUNC_NOCODE(IV_DIVIDE_ERROR);
+EXC_FUNC_NOCODE(IV_NON_MASKABLE_INTERRUPT);
+EXC_FUNC_NOCODE(IV_OVERFLOW);
+EXC_FUNC_NOCODE(IV_BOUND_RANGE);
+EXC_FUNC_NOCODE(IV_INVALID_OPCODE);
+EXC_FUNC_NOCODE(IV_DEVICE_NOT_AVAILABLE);
+EXC_FUNC_CODE(IV_DOUBLE_FAULT);
+EXC_FUNC_CODE(IV_INVALID_TSS);
+EXC_FUNC_CODE(IV_SEGMENT_NOT_PRESENT);
+EXC_FUNC_CODE(IV_STACK_FAULT);
+EXC_FUNC_CODE(IV_GENERAL_PROTECTION);
+EXC_FUNC_CODE(IV_PAGE_FAULT);
+EXC_FUNC_NOCODE(IV_X87_FPU_FP_ERROR);
+EXC_FUNC_CODE(IV_ALIGNMENT_CHECK);
+EXC_FUNC_NOCODE(IV_MACHINE_CHECK);
 
 #endif /* CONFIG_EXCEPTION_DEBUG */
 

arch/x86/core/float.c

@@ -425,5 +425,6 @@ void _FpNotAvailableExcHandler(NANO_ESF * pEsf)
 
 	_FpEnable(_nanokernel.current, enableOption);
 }
+_EXCEPTION_CONNECT_NOCODE(_FpNotAvailableExcHandler, IV_DEVICE_NOT_AVAILABLE);
 
 #endif /* CONFIG_FP_SHARING */

arch/x86/debug/Makefile

@@ -1,3 +1,3 @@
 ccflags-y += -I$(srctree)/kernel/nanokernel/include
 
-obj-$(CONFIG_GDB_SERVER) = gdb_arch.o gdb_dbg_regs.o gdb_arch_exc.o
+obj-$(CONFIG_GDB_SERVER) = gdb_arch.o gdb_dbg_regs.o

arch/x86/debug/gdb_arch.c

@@ -24,7 +24,6 @@
 #include <string.h>
 #include <debug/gdb_arch.h>
 #include <misc/debug/gdb_server.h>
-#include <asmPrv.h>
 
 #define TRACE_FLAG	0x0100 /* EFLAGS:TF */
 #define INT_FLAG	0x0200 /* EFLAGS:IF */
@@ -636,6 +635,7 @@ void gdb_trace_handler(NANO_ESF *esf)
 	(void)irq_lock();
 	_do_gdb_trace_handler(esf);
 }
+_EXCEPTION_CONNECT_NOCODE(gdb_trace_handler, IV_DEBUG);
 
 /**
  * @brief GDB breakpoint handler
@@ -658,6 +658,7 @@ void gdb_bp_handler(NANO_ESF *esf)
 
 	gdb_handler(GDB_EXC_BP, esf, GDB_SIG_TRAP);
 }
+_EXCEPTION_CONNECT_NOCODE(gdb_bp_handler, IV_BREAKPOINT);
 
 /**
  * @brief GDB division-by-zero handler
@@ -675,6 +676,7 @@ void gdb_div_by_zero_handler(NANO_ESF *esf)
 	gdb_debug_status = DEBUGGING;
 	gdb_handler(GDB_EXC_OTHER, esf, GDB_SIG_FPE);
 }
+_EXCEPTION_CONNECT_NOCODE(gdb_div_by_zero_handler, IV_DIVIDE_ERROR);
 
 /**
  * @brief GDB page fault handler
@@ -692,5 +694,6 @@ void gdb_pfault_handler(NANO_ESF *esf)
 	gdb_debug_status = DEBUGGING;
 	gdb_handler(GDB_EXC_OTHER, esf, GDB_SIG_SIGSEGV);
 }
+_EXCEPTION_CONNECT_CODE(gdb_pfault_handler, IV_PAGE_FAULT);
 
 #endif /* GDB_ARCH_HAS_RUNCONTROL */

arch/x86/include/asm_inline_gcc.h

@@ -28,12 +28,7 @@ extern "C" {
  * Include asm_inline.h instead
  */
 
-#ifdef _ASMLANGUAGE
-
-#define SYS_NANO_CPU_EXC_CONNECT(handler, vector) \
-NANO_CPU_EXC_CONNECT_NO_ERR(handler, vector, 0)
-
-#else /* !_ASMLANGUAGE */
+#ifndef _ASMLANGUAGE
 
 /**
  *