Panic: Save LR and code location in HFSR

Since Nami's PMIC reset clears panic data, we currently report only
a few fault registers (HFSR, MMSR, etc.), IPSR, r4, and r5. These
are included in a feedback report but not very useful. To debug a
crash happening remotely, this patch makes the assert handler,
the watchdog handler, and the panic handler store PC, LR, and some
additional info.

         | regs[1] | regs[3]  | regs[4]  |  HFSR
         | (IPSR)  | (r4)     | (r5)     | [29:2]
  -------+---------+----------+----------+--------------------
  Assert |   n/a   | __func__ | __FILE__ | [29:26] Flags (=3)
         |         |          |          | [25:10] Line#
         |         |          |          | [ 9: 2] Task#
  -------+---------+----------+----------+--------------------
  WDT    |   LR    |  Reason  |    PC    | [29:26] Flags (=4)
         |         |          |          | [ 9: 2] Task#
  -------+---------+----------+----------+--------------------
  Panic  |  IPSR   |    LR    |    PC    |     n/a
  -------+---------+----------+----------+--------------------

Note that this patch is created under several constraints imposed by
the released RO. Some of the constraints are as follows:

- It's the RO not RW who saves the panic data into BBRAM. This is for
  avoiding executing extra code in a restricted environment (= panic).
- If RO sees a watchdog reset without reason == PANIC_SW_WATCHDOG,
  it stores PANIC_SW_WATCHDOG in r4 and clears r5 and IPSR.
- BBRAM is already used up to the max (64 bytes).

Obviously, a patch for ToT would be very different (and much cleaner)
since it's free from these constraints. Most importantly, there is no
PMIC reset which erases panic data.

> crash assert

ASSERTION FAILURE '0' in command_crash() at common/panic_output.c:165

Rebooting...

--- UART initialized after reboot ---
[Reset cause: soft]
[Image: RO, nami_v1.1.8956+f067821734 2021-11-09 12:31:41 some@host]
[0.003853 init buttons]
[0.004072 Inits done]
Restarting system with PMIC.

> panicinfo

ASSERTION FAILURE in command_crash() at common/panic_output.c:165
r0 :         r1 :         r2 :         r3 :
r4 :100a9f82 r5 :100a89e0 r6 :00000000 r7 :00000000
r8 :00000000 r9 :00000000 r10:00000000 r11:00000000
r12:         sp :00000000 lr :         pc :

mmfs = 0, shcsr = 0, hfsr = c029428, dfsr = 0, ipsr = 100995ad

> crash divzero

=== PROCESS EXCEPTION: 06 ====== xPSR: 41000000 ===
r0 :00000000 r1 :100a8f09 r2 :400c4000 r3 :00000000
r4 :1009956f r5 :1009956e r6 :200c07c4 r7 :100a4fe3
r8 :100a4fde r9 :100a3a54 r10:00000000 r11:200c07d2
r12:00000000 sp :200c4508 lr :1009956f pc :1009956e
Undefined instructions
mmfs = 10000, shcsr = 70008, hfsr = 0, dfsr = 0, ipsr = 00000006

=========== Process Stack Contents ===========
200c4528: 00000002 200c4548 200c07c4 200c0400
200c4538: 00000002 1008d2c7 00000000 200c07c4
200c4548: 200c07c4 200c07ca 00000000 00000000
200c4558: 00000000 00000000 00000000 00000000

Rebooting...

> crashinfo

=== PROCESS EXCEPTION: 06 ====== xPSR: ffffffff ===
r0 :         r1 :         r2 :         r3 :
r4 :1009956f r5 :1009956e r6 :00000000 r7 :00000000
r8 :00000000 r9 :00000000 r10:00000000 r11:00000000
r12:         sp :00000000 lr :         pc :
Undefined instructions
mmfs = 10000, shcsr = 0, hfsr = 0, dfsr = 0, ipsr = 00000006

> crash watchdog

>### WATCHDOG PC=100995ae / LR=100995ad / pSP=200c4508 (task 10) ###
Time:     0x0000000009dd5f1d us,  165.502749 s
Deadline: 0x0000000009de2ab3 ->    0.052118 s from now
Active timers:
  Tsk 14  0x0000000009de2ab3 ->    0.052118
Task Ready Name         Events      Time (s)  StkUsed
   0 R << idle >>       00000001  134.736448   80/672
   1 R HOOKS            80000000    0.935280  648/800
   2   USB_CHG_P0       00000000    0.001806  312/672
   3   USB_CHG_P1       00000000    0.004606  320/672
   4 R CHARGER          80000000    1.657817  424/800
   5 R MOTIONSENSE      80000004    1.789985  560/928
   6   CHIPSET          00000000    0.000396  296/800
   7   KEYPROTO         00000000    0.002983  312/672
   8   PDCMD            00000000    0.000065  112/672
   9 R HOSTCMD          00000001    0.517519  568/800
  10 R CONSOLE          00000000    2.074095  332/800
  ...

> panicinfo

> ### WATCHDOG PC=100995ae / LR=100995ad / task=10
r0 :         r1 :         r2 :         r3 :
r4 :dead6664 r5 :100995ae r6 :00000000 r7 :00000000
r8 :00000000 r9 :00000000 r10:00000000 r11:00000000
r12:         sp :00000000 lr :         pc :

mmfs = 0, shcsr = 0, hfsr = 10000028, dfsr = 0, ipsr = 100995ad

BUG=b:200593658
BRANCH=Nami
TEST=Sona. Run crash assert. Verify function name, file name,
line number, task id are stored in r4, r5, ipsr by panicinfo
after PMIC reset.

Change-Id: I55b142ac4de14c05a8184a66ed127c9cbcd29745
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3271351
Reviewed-by: caveh jalali <caveh@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3457946
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
Commit-Queue: Ricardo Quesada <ricardoq@chromium.org>
Tested-by: Ricardo Quesada <ricardoq@chromium.org>
Auto-Submit: Ricardo Quesada <ricardoq@chromium.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/panic.h b/include/panic.h
index 47c749d027..d1099d6cce 100644
--- a/include/panic.h
+++ b/include/panic.h
@@ -188,6 +188,19 @@ void panic_set_reason(uint32_t reason, uint32_t info, uint8_t exception);
 void panic_get_reason(uint32_t *reason, uint32_t *info, uint8_t *exception);
 #endif
 
+#define HFSR_FLAG_ASSERT	3
+#define HFSR_FLAG_WATCHDOG	4
+
+/**
+ * Save code location in struct panic_data then reboot.
+ *
+ * @param func Function name (i.e. __func__). Stored in regs[3].
+ * @param file File path (i.e. __FILE__). Stored in regs[4].
+ * @param line Line number (i.e. __LINE__). Stored in HFSR[25:10].
+ */
+void panic_assert(const char *func, const char *file, uint16_t line)
+	__attribute__((noreturn));
+
 /**
  * Enable/disable bus fault handler
  *