arm: Dump additional fault registers in abort handlers

Paging code is tricky and figuring out what is wrong with it can be a
pain. This patch tries to ease the burden by giving a little more
information for prefetch and data aborts, dumping the Instruction Fault
Address Register (IFAR), Instruction Fault Status Register (IFSR) and
Auxiliary Instruction Fault Status Register (AIFSR) or the respective
Data registers. These contain additional information about the cause of
the abort (internal/external, write or read, fault subtype, etc.) and
the faulting address.

BUG=None
TEST=I have read through enough imprecise asynchronous external abort
reports with this patch that I learned the bit pattern by heart.

Change-Id: If1850c4a6df29b1195714ed0bdf025e51220e8ab
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: bf3b4924121825a5ceef7e5c14b7b307d01f8e9c
Original-Change-Id: I56a0557d4257f40b5b30c559c84eaf9b9f729099
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/223784
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9345
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

2 files changed, 60 insertions, 0 deletions

diff --git a/payloads/libpayload/arch/arm/exception.c b/payloads/libpayload/arch/arm/exception.c
index d100937295..6f1796018b 100644
--- a/payloads/libpayload/arch/arm/exception.c
+++ b/payloads/libpayload/arch/arm/exception.c
@@ -90,6 +90,18 @@ void exception_dispatch(u32 idx)
 
 	printf("%s Exception\n", names[idx]);
 	print_regs();
+	switch (idx) {
+	case EXC_PABORT:
+		printf("IFAR = %#.8x\n", read_ifar());
+		printf("IFSR = %#.8x\n", read_ifsr());
+		printf("AIFSR = %#.8x\n", read_aifsr());
+		break;
+	case EXC_DABORT:
+		printf("DFAR = %#.8x\n", read_dfar());
+		printf("DFSR = %#.8x\n", read_dfsr());
+		printf("ADFSR = %#.8x\n", read_adfsr());
+		break;
+	};
 	dump_stack(exception_state.regs[13], 512);
 	halt();
 }
diff --git a/payloads/libpayload/include/arm/arch/cache.h b/payloads/libpayload/include/arm/arch/cache.h
index 67f6fd4492..b258185b9b 100644
--- a/payloads/libpayload/include/arm/arch/cache.h
+++ b/payloads/libpayload/include/arm/arch/cache.h
@@ -268,6 +268,54 @@ static inline void write_sctlr(uint32_t val)
 	isb();
 }
 
+/* read data fault address register (DFAR) */
+static inline uint32_t read_dfar(void)
+{
+	uint32_t val;
+	asm volatile ("mrc p15, 0, %0, c6, c0, 0" : "=r" (val));
+	return val;
+}
+
+/* read data fault status register (DFSR) */
+static inline uint32_t read_dfsr(void)
+{
+	uint32_t val;
+	asm volatile ("mrc p15, 0, %0, c5, c0, 0" : "=r" (val));
+	return val;
+}
+
+/* read instruction fault address register (IFAR) */
+static inline uint32_t read_ifar(void)
+{
+	uint32_t val;
+	asm volatile ("mrc p15, 0, %0, c6, c0, 2" : "=r" (val));
+	return val;
+}
+
+/* read instruction fault status register (IFSR) */
+static inline uint32_t read_ifsr(void)
+{
+	uint32_t val;
+	asm volatile ("mrc p15, 0, %0, c5, c0, 1" : "=r" (val));
+	return val;
+}
+
+/* read auxiliary data fault status register (ADFSR) */
+static inline uint32_t read_adfsr(void)
+{
+	uint32_t val;
+	asm volatile ("mrc p15, 0, %0, c5, c1, 0" : "=r" (val));
+	return val;
+}
+
+/* read auxiliary instruction fault status register (AIFSR) */
+static inline uint32_t read_aifsr(void)
+{
+	uint32_t val;
+	asm volatile ("mrc p15, 0, %0, c5, c1, 1" : "=r" (val));
+	return val;
+}
+
 /*
  * Cache maintenance API
  */