Change in coreboot[master]: libpayload/x86/exception: Add ability to handle user defined interrupts

[Raul Rangel (Code Review)]

Raul Rangel has uploaded this change for review. ( https://review.coreboot.org/28100

Change subject: libpayload/x86/exception: Add ability to handle user defined interrupts
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libpayload/x86/exception: Add ability to handle user defined interrupts

I need to setup the APIC timer to fire interrupts. I would like to reuse
the existing interrupt table. So I extended it to support user defined
interrupts. I just added all 255 vectors so there wouldn't need to be
any additional build time configuration.

BUG=b:109749762
TEST=Wrote an interrupt handler and fired an APIC timer interrupt and
verified that vector 32 was returned.

Change-Id: Id9c2583c7c3d9be4a06a25e546e64399f2b0620c
Signed-off-by: Raul E Rangel 
---
M payloads/libpayload/arch/x86/exception.c
M payloads/libpayload/arch/x86/exception_asm.S
2 files changed, 34 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/00/28100/1

diff --git a/payloads/libpayload/arch/x86/exception.c b/payloads/libpayload/arch/x86/exception.c
index b562660..c9ab6bf 100644
--- a/payloads/libpayload/arch/x86/exception.c
+++ b/payloads/libpayload/arch/x86/exception.c
@@ -161,7 +161,15 @@
 void exception_dispatch(void)
 {
    u32 vec = exception_state->vector;
-	die_if(vec >= EXC_COUNT || !names[vec], "Bad exception vector %u", vec);
+
+	/* Handle user defined vectors */
+	if (vec >= 32 && vec <= 255) {
+		die_if(!hook || !hook(vec),
+		       "Hook required to handle user defined vector %u\n", vec);
+	}
+
+	die_if(vec >= EXC_COUNT || !names[vec], "Bad exception vector %u\n",
+	       vec);

if (hook && hook(vec))
    	return;
diff --git a/payloads/libpayload/arch/x86/exception_asm.S b/payloads/libpayload/arch/x86/exception_asm.S
index a8f9a1d..5bbe69e 100644
--- a/payloads/libpayload/arch/x86/exception_asm.S
+++ b/payloads/libpayload/arch/x86/exception_asm.S
@@ -68,6 +68,14 @@
    jmp	exception_common
    .endm

+	.altmacro
+	.macro  user_defined_stubs from, to
+	stub	\from
+	.if     \to-\from
+	user_defined_stubs	%(from+1),\to
+	.endif
+	.endm
+
    stub 0
    stub 1
    stub 2
@@ -100,6 +108,11 @@
    stub 29
    stub_err 30
    stub 31
+	/* Split the macro so we avoid a stack overflow. */
+	user_defined_stubs 32, 63
+	user_defined_stubs 64, 127
+	user_defined_stubs 128, 191
+	user_defined_stubs 192, 255

exception_common:
    /*
@@ -215,6 +228,14 @@
    .long \target
    .endm

+	.altmacro
+	.macro  user_defined_gates from, to
+	interrupt_gate	exception_stub_\from
+	.if     \to-\from
+	user_defined_gates	%(from+1),\to
+	.endif
+	.endm
+
    .align 8
    .global	idt
 idt:
@@ -250,6 +271,10 @@
    interrupt_gate exception_stub_29
    interrupt_gate exception_stub_30
    interrupt_gate exception_stub_31
+	user_defined_gates 32, 63
+	user_defined_gates 64, 127
+	user_defined_gates 128, 191
+	user_defined_gates 192, 255
 idt_end:

/* IDT pointer for use with lidt */