libpayload: x86: Add support for catching processor exceptions.

This functionality is already available for ARM, so lets add it to x86 as
well. We'll want to be able to hook exceptions when running as a remote GDB
target.

Change-Id: I42f640b08eb9eb86a1bcab3c327f7780191a2eb5
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/179601
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit 5b8cf0c9f70a7e14766a2b095e6739a8d6321a34)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6898
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>

4 files changed, 494 insertions, 0 deletions

diff --git a/payloads/libpayload/arch/x86/Makefile.inc b/payloads/libpayload/arch/x86/Makefile.inc
index 8efbc12831..549a6303e7 100644
--- a/payloads/libpayload/arch/x86/Makefile.inc
+++ b/payloads/libpayload/arch/x86/Makefile.inc
@@ -32,6 +32,7 @@ libc-y += main.c sysinfo.c
 libc-y += timer.c coreboot.c util.S
 libc-y += exec.S virtual.c
 libc-y += string.c
+libc-y += exception_asm.S exception.c
 
 libcbfs-$(CONFIG_LP_CBFS) += rom_media.c
 
diff --git a/payloads/libpayload/arch/x86/exception.c b/payloads/libpayload/arch/x86/exception.c
new file mode 100644
index 0000000000..a9a65ca5a2
--- /dev/null
+++ b/payloads/libpayload/arch/x86/exception.c
@@ -0,0 +1,199 @@
+/*
+ * This file is part of the libpayload project.
+ *
+ * Copyright 2013 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <exception.h>
+#include <libpayload.h>
+#include <stdint.h>
+
+uint8_t exception_stack[0x1000] __attribute__((aligned(8)));
+extern void *exception_stack_end;
+
+struct exception_state
+{
+	u32 eax;
+	u32 ecx;
+	u32 edx;
+	u32 ebx;
+	u32 esp;
+	u32 ebp;
+	u32 esi;
+	u32 edi;
+	u32 eip;
+	u32 eflags;
+	u32 cs;
+	u32 ss;
+	u32 ds;
+	u32 es;
+	u32 fs;
+	u32 gs;
+	u32 error_code;
+	u32 vector;
+} __attribute__((packed));
+
+struct exception_info
+{
+	const char *name;
+	void (*error_code_printer)(u32 code);
+};
+
+static void print_segment_error_code(u32 code)
+{
+	printf("%#x - descriptor %#x in the ", code, (code >> 3) & 0x1f);
+	if (code & (0x1 << 1)) {
+		printf("IDT");
+	} else {
+		if (code & 0x04)
+			printf("LDT");
+		else
+			printf("GDT");
+	}
+	if (code & (0x1 << 0))
+		printf(", external to the CPU");
+	else
+		printf(", internal to the CPU");
+}
+
+static void print_page_fault_error_code(u32 code)
+{
+	printf("%#x -", code);
+	if (code & (0x1 << 0))
+		printf(" page protection");
+	else
+		printf(" page not present");
+	if (code & (0x1 << 1))
+		printf(", write");
+	else
+		printf(", read");
+	if (code & (0x1 << 2))
+		printf(", user");
+	else
+		printf(", supervisor");
+	if (code & (0x1 << 3))
+		printf(", reserved bits set");
+	if (code & (0x1 << 4))
+		printf(", instruction fetch");
+}
+
+static void print_raw_error_code(u32 code)
+{
+	printf("%#x", code);
+}
+
+static struct exception_info exceptions[] = {
+	[0] =  { .name = "divide by zero" },
+	[1] =  { .name = "debug" },
+	[2] =  { .name = "non-maskable-interrupt" },
+	[3] =  { .name = "breakpoint" },
+	[4] =  { .name = "overflow" },
+	[5] =  { .name = "bound range" },
+	[6] =  { .name = "invalid opcode" },
+	[7] =  { .name = "device not available" },
+	[8] =  { .name = "double fault",
+		 .error_code_printer = &print_raw_error_code },
+	[10] = { .name = "invalid tss",
+		 .error_code_printer = &print_segment_error_code },
+	[11] = { .name = "segment not present",
+		 .error_code_printer = &print_segment_error_code },
+	[12] = { .name = "stack",
+		 .error_code_printer = &print_segment_error_code },
+	[13] = { .name = "general protection",
+		 .error_code_printer = &print_segment_error_code },
+	[14] = { .name = "page fault",
+		 .error_code_printer = &print_page_fault_error_code },
+	[16] = { .name = "x87 floating point" },
+	[17] = { .name = "alignment check",
+		 .error_code_printer = &print_raw_error_code },
+	[18] = { .name = "machine check" },
+	[19] = { .name = "SIMD floating point" },
+	[30] = { .name = "security",
+		 .error_code_printer = &print_raw_error_code },
+};
+
+static void dump_stack(uintptr_t addr, size_t bytes)
+{
+	int i, j;
+	const int line = 8;
+	uint32_t *ptr = (uint32_t *)(addr & ~(line * sizeof(*ptr) - 1));
+
+	printf("Dumping stack:\n");
+	for (i = bytes / sizeof(*ptr); i >= 0; i -= line) {
+		printf("%p: ", ptr + i);
+		for (j = i; j < i + line; j++)
+			printf("%08x ", *(ptr + j));
+		printf("\n");
+	}
+}
+
+void exception_handler(void);
+void exception_handler(void)
+{
+	struct exception_state *state =
+		(void *)((u8 *)exception_stack_end - sizeof(*state));
+
+	struct exception_info *info = NULL;
+	if (state->vector < ARRAY_SIZE(exceptions))
+		info = &exceptions[state->vector];
+
+	if (info)
+		printf("Exception %d (%s)\n", state->vector, info->name);
+	else
+		printf("Unrecognized exception %d\n", state->vector);
+	if (info->error_code_printer) {
+		printf("Error code: ");
+		info->error_code_printer(state->error_code);
+		printf("\n");
+	}
+	printf("EIP:    0x%08x\n", state->eip);
+	printf("CS:     0x%04x\n", state->cs);
+	printf("EFLAGS: 0x%08x\n", state->eflags);
+	printf("EAX:    0x%08x\n", state->eax);
+	printf("ECX:    0x%08x\n", state->ecx);
+	printf("EDX:    0x%08x\n", state->edx);
+	printf("EBX:    0x%08x\n", state->ebx);
+	printf("ESP:    0x%08x\n", state->esp);
+	printf("EBP:    0x%08x\n", state->ebp);
+	printf("ESI:    0x%08x\n", state->esi);
+	printf("EDI:    0x%08x\n", state->edi);
+	printf("DS:     0x%04x\n", state->ds);
+	printf("ES:     0x%04x\n", state->es);
+	printf("SS:     0x%04x\n", state->ss);
+	printf("FS:     0x%04x\n", state->fs);
+	printf("GS:     0x%04x\n", state->gs);
+
+	dump_stack(state->esp, 512);
+
+	halt();
+}
+
+void exception_init_asm(void);
+void exception_init(void)
+{
+	exception_stack_end = exception_stack + sizeof(exception_stack);
+	exception_init_asm();
+}
diff --git a/payloads/libpayload/arch/x86/exception_asm.S b/payloads/libpayload/arch/x86/exception_asm.S
new file mode 100644
index 0000000000..c56a7a0bab
--- /dev/null
+++ b/payloads/libpayload/arch/x86/exception_asm.S
@@ -0,0 +1,291 @@
+/*
+ * This file is part of the libpayload project.
+ *
+ * Copyright 2013 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+	.align 4
+	.global exception_stack_end
+exception_stack_end:
+	.long 0
+
+/* Some temporary variables which are used while saving exception state. */
+vector:
+	.long 0
+error_code:
+	.long 0
+old_esp:
+	.long 0
+old_eax:
+	.long 0
+
+	.align 8
+
+/*
+ * Each exception vector has a small stub associated with it which sets aside
+ * the error code, if any, records which vector we entered from, and calls
+ * the common exception entry point. Some exceptions have error codes and some
+ * don't, so we have a macro for each type.
+ */
+
+	.macro stub num
+exception_stub_\num:
+	movl	$0, error_code
+	movl	$\num, vector
+	jmp	exception_common
+	.endm
+
+	.macro stub_err num
+exception_stub_\num:
+	popl	error_code
+	movl	$\num, vector
+	jmp	exception_common
+	.endm
+
+	stub 0
+	stub 1
+	stub 2
+	stub 3
+	stub 4
+	stub 5
+	stub 6
+	stub 7
+	stub_err 8
+	stub 9
+	stub_err 10
+	stub_err 11
+	stub_err 12
+	stub_err 13
+	stub_err 14
+	stub 15
+	stub 16
+	stub_err 17
+	stub 18
+	stub 19
+	stub 20
+	stub 21
+	stub 22
+	stub 23
+	stub 24
+	stub 25
+	stub 26
+	stub 27
+	stub 28
+	stub 29
+	stub_err 30
+	stub 31
+
+exception_common:
+	/*
+	 * Save off the stack pointer and old eax value and install the
+	 * exception stack. eax points to the old stack which has the
+	 * exception ip, cs, and flags.
+	 */
+	mov	%esp, old_esp
+	addl	$12, old_esp
+	mov	%eax, old_eax
+	mov	%esp, %eax
+	mov	exception_stack_end, %esp
+
+	/*
+	 * Push values onto the top of the exception stack to form an
+	 * exception state structure.
+	 */
+	pushl	vector
+	pushl	error_code
+	pushl	%gs
+	pushl	%fs
+	pushl	%es
+	pushl	%ds
+	pushl	%ss
+	pushl	4(%eax)
+	pushl	8(%eax)
+	pushl	(%eax)
+	pushl	%edi
+	pushl	%esi
+	pushl	%ebp
+	pushl	old_esp
+	pushl	%ebx
+	pushl	%edx
+	pushl	%ecx
+	pushl	old_eax
+
+	/*
+	 * Call the C exception handler. It will find the exception state on
+	 * the exception stack. Not passing parameters means we don't have to
+	 * worry about what ABI is being used.
+	 */
+	call	exception_handler
+
+	/*
+	 * Restore state from the exception state structure, including any
+	 * changes that might have been made.
+	 */
+	popl	old_eax
+	popl	%ecx
+	popl	%edx
+	popl	%ebx
+	popl	old_esp
+
+	mov	old_esp, %eax
+	subl	$12, %eax
+
+	popl	%ebp
+	popl	%esi
+	popl	%edi
+	popl	(%eax)
+	popl	8(%eax)
+	popl	4(%eax)
+	popl	%ss
+	popl	%ds
+	popl	%es
+	popl	%fs
+	popl	%gs
+
+	mov	%eax, %esp
+	mov	old_eax, %eax
+
+	/* Return from the exception. */
+	iretl
+
+/*
+ * We need segment selectors for the IDT, so we need to know where things are
+ * in the GDT. We set one up here which is pretty standard and largely copied
+ * from coreboot.
+ */
+	.align 8
+gdt:
+	/* selgdt 0, unused */
+	.word 0x0000, 0x0000
+	.byte 0x00, 0x00, 0x00, 0x00
+
+	/* selgdt 8, unused */
+	.word 0x0000, 0x0000
+	.byte 0x00, 0x00, 0x00, 0x00
+
+	/* selgdt 0x10, flat 4GB code segment */
+        .word 0xffff, 0x0000
+	.byte 0x00, 0x9b, 0xcf, 0x00
+
+	/* selgdt 0x18, flat 4GB data segment */
+	.word 0xffff, 0x0000
+	.byte 0x00, 0x93, 0xcf, 0x00
+gdt_end:
+
+/* GDT pointer for use with lgdt */
+gdt_ptr:
+	.word	gdt_end - gdt - 1
+	.long	gdt
+
+	/*
+	 * Record the target and construct the actual entry at init time. This
+	 * is necessary because the linker doesn't want to construct the entry
+	 * for us.
+	 */
+	.macro interrupt_gate target
+	.long \target
+	.long \target
+	.endm
+
+	.align 8
+	.global	idt
+idt:
+	interrupt_gate exception_stub_0
+	interrupt_gate exception_stub_1
+	interrupt_gate exception_stub_2
+	interrupt_gate exception_stub_3
+	interrupt_gate exception_stub_4
+	interrupt_gate exception_stub_5
+	interrupt_gate exception_stub_6
+	interrupt_gate exception_stub_7
+	interrupt_gate exception_stub_8
+	interrupt_gate exception_stub_9
+	interrupt_gate exception_stub_10
+	interrupt_gate exception_stub_11
+	interrupt_gate exception_stub_12
+	interrupt_gate exception_stub_13
+	interrupt_gate exception_stub_14
+	interrupt_gate exception_stub_15
+	interrupt_gate exception_stub_16
+	interrupt_gate exception_stub_17
+	interrupt_gate exception_stub_18
+	interrupt_gate exception_stub_19
+	interrupt_gate exception_stub_20
+	interrupt_gate exception_stub_21
+	interrupt_gate exception_stub_22
+	interrupt_gate exception_stub_23
+	interrupt_gate exception_stub_24
+	interrupt_gate exception_stub_25
+	interrupt_gate exception_stub_26
+	interrupt_gate exception_stub_27
+	interrupt_gate exception_stub_28
+	interrupt_gate exception_stub_29
+	interrupt_gate exception_stub_30
+	interrupt_gate exception_stub_31
+idt_end:
+
+/* IDT pointer for use with lidt */
+idt_ptr:
+	.word idt_end - idt - 1
+	.long idt
+
+	.global exception_init_asm
+exception_init_asm:
+	/* Save eax so we can use it as a temporary variable. */
+	pushl	%eax
+
+	/* Install the GDT. */
+	lgdt	gdt_ptr
+	/* Load the segment registers from it. */
+	ljmp	$0x10, $1f
+1:	movl	$0x18, %eax
+	movl	%eax, %ds
+	movl	%eax, %es
+	movl	%eax, %ss
+	movl	%eax, %fs
+	movl	%eax, %gs
+
+	/*
+	 * Loop over the entries which start out as two copies of the target
+	 * address. We can turn them into real interrupt gates by selectively
+	 * replacing certain bit fields.
+	 */
+	movl	$idt, %eax
+1:
+	andl	$0x0000ffff, (%eax)
+	orl	$0x00100000, (%eax)
+	andl	$0xffff0000, 4(%eax)
+	orl	$0x0000ee00, 4(%eax)
+	addl	$8, %eax
+	cmp	$idt_end, %eax
+	jne	1b
+
+	/* Install the IDT. */
+	lidt	idt_ptr
+
+	/* Restore eax and return to the caller. */
+	popl	%eax
+	ret
diff --git a/payloads/libpayload/arch/x86/main.c b/payloads/libpayload/arch/x86/main.c
index c788f0f670..ee52a937e6 100644
--- a/payloads/libpayload/arch/x86/main.c
+++ b/payloads/libpayload/arch/x86/main.c
@@ -27,6 +27,7 @@
  * SUCH DAMAGE.
  */
 
+#include <exception.h>
 #include <libpayload.h>
 
 unsigned long loader_eax;  /**< The value of EAX passed from the loader */
@@ -54,6 +55,8 @@ void start_main(void)
 	console_init();
 #endif
 
+	exception_init();
+
 	/*
 	 * Any other system init that has to happen before the
 	 * user gets control goes here.