libpayload: Rework exception hook interface

This patch makes some slight changes to the exception hook interface.
The old code provides a different handler hook for every exception
type... however, in practice all those hook functions often need to look
very similar, so this creates more boilerplate than it removes. The new
interface just allows for a single hook with the exception type passed
as an argument, and the consumer can signal whether the exception was
handled through the return value. (Right now this still only supports
one consumer, but it could easily be extended to walk through a list of
hooks if the need arises.)

Also move the excepton state from an argument to a global. This avoids a
lot of boilerplate since some consumers need to change the state from
many places, so they would have to pass the same pointer around many
times. It also removes the false suggestion that the exception state was
not global and you could have multiple copies of it (which the exception
core doesn't support for any architecture).

On the ARM side, the exception state is separated from the exception
stack for easier access. (This requires some assembly changes, and I
threw in a few comments and corrected the immediate sigils from '$' to
the official '#' while I'm there.) Since the exception state is now both
stored and loaded through an indirection pointer, this allows for some
very limited reentrance (you could point it to a different struct while
handling an exception, and while you still won't be able to return to
the outer-level exception from there, you could at least swap out the
pointer and return back to System Mode in one go).

BUG=chrome-os-partner:18390
TEST=Made sure normal exceptions still get dumped correctly on both
archs.

Original-Change-Id: I5d9a934fab7c14ccb2c9d7ee4b3465c825521fa2
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/202562
Original-Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
(cherry picked from commit 97542110f0b385b9b8d89675866e65db8ca32aeb)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

*** Squashed to prevent build failures. ***

libpayload: align arm64 with new exception handling model

The exception handling was previously updated, however the
arm64 changes raced with hat one. Make the arm64 align with
the new model. Without these changes compilation will fail.

BUG=None
BRANCH=None
TEST=Can build libpayload for rush.

Original-Change-Id: I320b39a57b985d1f87446ea7757955664f8dba8f
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/204402
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit 0080df41b311ef20f9214b386fa4e38ee54aa1a1)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I9a0bb3848cf5286f9f4bb08172a9f4a15278348e
Reviewed-on: http://review.coreboot.org/8117
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

4 files changed, 39 insertions, 21 deletions

diff --git a/payloads/libpayload/include/arm/arch/exception.h b/payloads/libpayload/include/arm/arch/exception.h
index c6864a5ad2..fbbce5ed3d 100644
--- a/payloads/libpayload/include/arm/arch/exception.h
+++ b/payloads/libpayload/include/arm/arch/exception.h
@@ -32,13 +32,19 @@
 
 #include <stdint.h>
 
+void exception_dispatch(u32 idx);
 void set_vbar(uint32_t vbar);
 
 struct exception_state
 {
-	uint32_t cpsr;
-	uint32_t regs[16];
+	u32 regs[16];
+	u32 cpsr;
 } __attribute__((packed));
+extern struct exception_state exception_state;
+
+extern u32 exception_stack[];
+extern u32 *exception_stack_end;
+extern struct exception_state *exception_state_ptr;
 
 enum {
 	EXC_UNDEF = 1,
diff --git a/payloads/libpayload/include/arm64/arch/exception.h b/payloads/libpayload/include/arm64/arch/exception.h
index f4a7552db9..44a4e5998d 100644
--- a/payloads/libpayload/include/arm64/arch/exception.h
+++ b/payloads/libpayload/include/arm64/arch/exception.h
@@ -41,6 +41,8 @@ struct exception_state
 	uint64_t regs[31];
 } __attribute__((packed));
 
+extern struct exception_state *exception_state;
+
 enum {
 	EXC_INV = 0,
 	EXC_SYNC = 1,
diff --git a/payloads/libpayload/include/exception.h b/payloads/libpayload/include/exception.h
index 1d9b832c07..67923ea9af 100644
--- a/payloads/libpayload/include/exception.h
+++ b/payloads/libpayload/include/exception.h
@@ -32,9 +32,10 @@
 
 #include <arch/exception.h>
 
-typedef void (*exception_hook)(int type, struct exception_state *state);
+/* Return 1 if the exception was handled, 0 to proceed to the next handler. */
+typedef int (*exception_hook)(u32 type);
 
 void exception_init(void);
-void exception_install_hook(int type, exception_hook hook);
+void exception_install_hook(exception_hook h);
 
 #endif
diff --git a/payloads/libpayload/include/x86/arch/exception.h b/payloads/libpayload/include/x86/arch/exception.h
index 82f2ca0a32..fe222aa4f2 100644
--- a/payloads/libpayload/include/x86/arch/exception.h
+++ b/payloads/libpayload/include/x86/arch/exception.h
@@ -32,28 +32,37 @@
 
 #include <stdint.h>
 
-void exception_dispatch(void);
 void exception_init_asm(void);
+void exception_dispatch(void);
 
 struct exception_state
 {
-	uint32_t eax;
-	uint32_t ecx;
-	uint32_t edx;
-	uint32_t ebx;
-	uint32_t esp;
-	uint32_t ebp;
-	uint32_t esi;
-	uint32_t edi;
-	uint32_t eip;
-	uint32_t eflags;
-	uint32_t cs;
-	uint32_t ss;
-	uint32_t ds;
-	uint32_t es;
-	uint32_t fs;
-	uint32_t gs;
+	/* Careful: x86/gdb.c currently relies on the size and order of regs. */
+	struct {
+		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;
+	} regs;
+	u32 error_code;
+	u32 vector;
 } __attribute__((packed));
+extern struct exception_state *exception_state;
+
+extern u32 exception_stack[];
+extern u32 *exception_stack_end;
 
 enum {
 	EXC_DE = 0, /* Divide by zero */