/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2017 Ash Logan (QuarkTheAwesome)
 *
 *  RetroArch is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with RetroArch.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

/* TODO: Program exceptions don't seem to work. Good thing they almost never happen. */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <wiiu/os.h>
#include "wiiu_dbg.h"
#include "exception_handler.h"
#include "version.h"
#ifdef HAVE_GIT_VERSION
#include "version_git.h"
#endif
/*	Settings */
#define NUM_STACK_TRACE_LINES 5

/*	Externals
	From the linker scripts.
*/
extern unsigned int __code_start;
#define TEXT_START (unsigned int)&__code_start
extern unsigned int __code_end;
#define TEXT_END (unsigned int)&__code_end

void test_os_exceptions(void);
void exception_print_symbol(uint32_t addr);

typedef struct _framerec
{
   struct _framerec* up;
   void* lr;
} frame_rec, *frame_rec_t;

/*	Fill in a few gaps in thread.h
	Dimok calls these exception_specific0 and 1;
	though we may as well name them by their function.
*/
#define dsisr __unknown[0]
#define dar __unknown[1]

/*	Some bitmasks for determining DSI causes.
	Taken from the PowerPC Programming Environments Manual (32-bit).
*/

/* Set if the EA is unmapped. */
#define DSISR_TRANSLATION_MISS 0x40000000
/* Set if the memory accessed is protected. */
#define DSISR_TRANSLATION_PROT 0x8000000
/* Set if certain instructions are used on uncached memory (see manual) */
#define DSISR_BAD_CACHING 0x4000000
/* Set if the offending operation is a write, clear for a read. */
#define DSISR_WRITE_ATTEMPTED 0x2000000
/* Set if the memory accessed is a DABR match */
#define DSISR_DABR_MATCH 0x400000
/*	ISI cause bitmasks, same source */
#define SRR1_ISI_TRANSLATION_MISS 0x40000000
#define SRR1_ISI_TRANSLATION_PROT 0x8000000
/*	PROG cause bitmasks, guess where from */
/* Set on floating-point exceptions */
#define SRR1_PROG_IEEE_FLOAT 0x100000
/* Set on an malformed instruction (can't decode) */
#define SRR1_PROG_BAD_INSTR 0x80000
/* Set on a privileged instruction executing in userspace */
#define SRR1_PROG_PRIV_INSTR 0x40000
/* Set on a trap instruction */
#define SRR1_PROG_TRAP 0x20000
/* Clear if srr0 points to the address that caused the exception (yes, really) */
#define SRR1_PROG_SRR0_INACCURATE 0x10000

#define buf_add(...) wiiu_exception_handler_pos += sprintf(exception_msgbuf + wiiu_exception_handler_pos, __VA_ARGS__)
size_t wiiu_exception_handler_pos = 0;
char* exception_msgbuf;

void __attribute__((__noreturn__)) exception_cb(OSContext* ctx, OSExceptionType type)
{
   /*	No message buffer available, fall back onto MEM1 */
   if (!exception_msgbuf || !OSEffectiveToPhysical(exception_msgbuf))
      exception_msgbuf = (char*)0xF4000000;

   /*	First up, the pretty header that tells you wtf just happened */
   if (type == OS_EXCEPTION_TYPE_DSI)
   {
      /*	Exception type and offending instruction location */
      buf_add("DSI: Instr at %08" PRIX32, ctx->srr0);
      /*	Was this a read or a write? */
      if (ctx->dsisr & DSISR_WRITE_ATTEMPTED)
         buf_add(" bad write to");
      else
         buf_add(" bad read from");

      /*	So why was it bad?
         Other causes (DABR) don't have a message to go with them. */
      if (ctx->dsisr & DSISR_TRANSLATION_MISS)
         buf_add(" unmapped memory at");
      else if (ctx->dsisr & DSISR_TRANSLATION_PROT)
         buf_add(" protected memory at");
      else if (ctx->dsisr & DSISR_BAD_CACHING)
         buf_add(" uncached memory at");

      buf_add(" %08" PRIX32 "\n", ctx->dar);
   }
   else if (type == OS_EXCEPTION_TYPE_ISI)
   {
      buf_add("ISI: Bad execute of");
      if (ctx->srr1 & SRR1_ISI_TRANSLATION_PROT)
         buf_add(" protected memory at");
      else if (ctx->srr1 & SRR1_ISI_TRANSLATION_MISS)
         buf_add(" unmapped memory at");

      buf_add(" %08" PRIX32 "\n", ctx->srr0);
   }
   else if (type == OS_EXCEPTION_TYPE_PROGRAM)
   {
      buf_add("PROG:");
      if (ctx->srr1 & SRR1_PROG_BAD_INSTR)
         buf_add(" Malformed instruction at");
      else if (ctx->srr1 & SRR1_PROG_PRIV_INSTR)
         buf_add(" Privileged instruction in userspace at");
      else if (ctx->srr1 & SRR1_PROG_IEEE_FLOAT)
         buf_add(" Floating-point exception at");
      else if (ctx->srr1 & SRR1_PROG_TRAP)
         buf_add(" Trap conditions met at");
      else
         buf_add(" Out-of-spec error (!) at");

      if (ctx->srr1 & SRR1_PROG_SRR0_INACCURATE)
         buf_add("%08" PRIX32 "-ish\n", ctx->srr0);
      else
         buf_add("%08" PRIX32 "\n", ctx->srr0);
   }

   /*	Add register dump
      There's space for two more regs at the end of the last line...
      Any ideas for what to put there? */
   buf_add( \
         "r0  %08" PRIX32 " r1  %08" PRIX32 " r2  %08" PRIX32 " r3  %08" PRIX32 " r4  %08" PRIX32 "\n" \
         "r5  %08" PRIX32 " r6  %08" PRIX32 " r7  %08" PRIX32 " r8  %08" PRIX32 " r9  %08" PRIX32 "\n" \
         "r10 %08" PRIX32 " r11 %08" PRIX32 " r12 %08" PRIX32 " r13 %08" PRIX32 " r14 %08" PRIX32 "\n" \
         "r15 %08" PRIX32 " r16 %08" PRIX32 " r17 %08" PRIX32 " r18 %08" PRIX32 " r19 %08" PRIX32 "\n" \
         "r20 %08" PRIX32 " r21 %08" PRIX32 " r22 %08" PRIX32 " r23 %08" PRIX32 " r24 %08" PRIX32 "\n" \
         "r25 %08" PRIX32 " r26 %08" PRIX32 " r27 %08" PRIX32 " r28 %08" PRIX32 " r29 %08" PRIX32 "\n" \
         "r30 %08" PRIX32 " r31 %08" PRIX32 " lr  %08" PRIX32 " sr1 %08" PRIX32 " dsi %08" PRIX32 "\n" \
         "ctr %08" PRIX32 " cr  %08" PRIX32 " xer %08" PRIX32 "\n",\
         ctx->gpr[0],  ctx->gpr[1],  ctx->gpr[2],  ctx->gpr[3],  ctx->gpr[4],  \
         ctx->gpr[5],  ctx->gpr[6],  ctx->gpr[7],  ctx->gpr[8],  ctx->gpr[9],  \
         ctx->gpr[10], ctx->gpr[11], ctx->gpr[12], ctx->gpr[13], ctx->gpr[14], \
         ctx->gpr[15], ctx->gpr[16], ctx->gpr[17], ctx->gpr[18], ctx->gpr[19], \
         ctx->gpr[20], ctx->gpr[21], ctx->gpr[22], ctx->gpr[23], ctx->gpr[24], \
         ctx->gpr[25], ctx->gpr[26], ctx->gpr[27], ctx->gpr[28], ctx->gpr[29], \
         ctx->gpr[30], ctx->gpr[31], ctx->lr,      ctx->srr1,    ctx->dsisr,   \
         ctx->ctr,     ctx->cr,      ctx->xer                                  \
         );

   /*	Stack trace!
      First, let's print the PC... */
   exception_print_symbol(ctx->srr0);

   if (ctx->gpr[1])
   {
      int i;
      /*	Then the addresses off the stack.
         Code borrowed from Dimok's exception handler. */
      frame_rec_t p = (frame_rec_t)ctx->gpr[1];
      if ((unsigned int)p->lr != ctx->lr)
         exception_print_symbol(ctx->lr);

      for (i = 0; i < NUM_STACK_TRACE_LINES && p->up; p = p->up, i++)
         exception_print_symbol((unsigned int)p->lr);
   }
   else
      buf_add("Stack pointer invalid. Could not trace further.\n");

#ifdef HAVE_GIT_VERSION
   buf_add("RetroArch " PACKAGE_VERSION " (%s) built " __DATE__, retroarch_git_version);
#else
   buf_add("RetroArch " PACKAGE_VERSION " built " __DATE__);
#endif
   OSFatal(exception_msgbuf);
   for (;;) {}
}

BOOL __attribute__((__noreturn__)) exception_dsi_cb(OSContext* ctx)
{
	exception_cb(ctx, OS_EXCEPTION_TYPE_DSI);
}

BOOL __attribute__((__noreturn__)) exception_isi_cb(OSContext* ctx)
{
   exception_cb(ctx, OS_EXCEPTION_TYPE_ISI);
}

BOOL __attribute__((__noreturn__)) exception_prog_cb(OSContext* ctx)
{
	exception_cb(ctx, OS_EXCEPTION_TYPE_PROGRAM);
}

void exception_print_symbol(uint32_t addr)
{
   /*	Check if addr is within this RPX's .text */
   if (addr >= TEXT_START && addr < TEXT_END)
   {
      char symbolName[64];
      OSGetSymbolName(addr, symbolName, 63);

      buf_add("%08" PRIX32 "(%08" PRIX32 "):%s\n",
            addr, addr - TEXT_START, symbolName);
   }
   /*	Check if addr is within the system library area... */
   else if ((addr >= 0x01000000 && addr < 0x01800000) ||
         /*	Or the rest of the app executable area.
            I would have used whatever method JGeckoU uses to determine
            the real lowest address, but *someone* didn't make it open-source :/ */
         (addr >= 0x01800000 && addr < 0x1000000))
   {
      char *seperator = NULL;
      char symbolName[64];

      OSGetSymbolName(addr, symbolName, 63);

      /*	Extract RPL name and try and find its base address */
      seperator = strchr(symbolName, '|');

      if (seperator)
      {
         void* libAddr = NULL;
         /*	Isolate library name; should end with .rpl
            (our main RPX was caught by another test case above) */
         *seperator = '\0';
         /*	Try for a base address */
         OSDynLoad_Acquire(symbolName, &libAddr);

         /*	Special case for coreinit; which has broken handles */
         if (!strcmp(symbolName, "coreinit.rpl"))
         {
            void* PPCExit_addr;
            OSDynLoad_FindExport(libAddr, 0, "__PPCExit", &PPCExit_addr);
            libAddr = PPCExit_addr - 0x180;
         }

         *seperator = '|';

         /*	We got one! */
         if (libAddr)
         {
            buf_add("%08" PRIX32 "(%08" PRIX32 "):%s\n", addr, addr - (unsigned int)libAddr, symbolName);
            OSDynLoad_Release(libAddr);
            return;
         }
      }
      /*	Ah well. We can still print the basics. */
      buf_add("%08" PRIX32 "(        ):%s\n", addr, symbolName);
   }

   /*	Check if addr is in the HBL range
      TODO there's no real reason we couldn't find the symbol here,
      it's just laziness and arguably uneccesary bloat */
   else if (addr >= 0x00800000 && addr < 0x01000000)
      buf_add("%08" PRIX32 "(%08" PRIX32 "):<unknown:HBL>\n", addr, addr - 0x00800000);
   /*	If all else fails, just say "unknown" */
   else
      buf_add("%08" PRIX32 "(        ):<unknown>\n", addr);
}

/*	void setup_os_exceptions(void)
	Install and initialize the exception handler.
*/
void setup_os_exceptions(void)
{
   exception_msgbuf = malloc(4096);
   OSSetExceptionCallback(OS_EXCEPTION_TYPE_DSI, exception_dsi_cb);
   OSSetExceptionCallback(OS_EXCEPTION_TYPE_ISI, exception_isi_cb);
   OSSetExceptionCallback(OS_EXCEPTION_TYPE_PROGRAM, exception_prog_cb);
   test_os_exceptions();
}

/*	void test_os_exceptions(void)
	Used for debugging. Insert code here to induce a crash.
*/
void test_os_exceptions(void)
{
   /*Write to 0x00000000; causes DSI */
#if 0
   __asm__ volatile (
         "li %r3, 0 \n" \
         "stw %r3, 0(%r3) \n"
         );
   DCFlushRange((void*)0, 4);
#endif

   /*Malformed instruction, causes PROG. Doesn't seem to work. */
#if 0
   __asm__ volatile (
         ".int 0xDEADC0DE"
         );
#endif

   /* Jump to 0; causes ISI */
#if 0
   void (*testFunc)() = (void(*)())0;
   testFunc();
#endif
}