/*
* This file is part of Luma3DS
* Copyright (C) 2016-2017 Aurora Wright, TuxSH
*
* This program 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 Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*
* Additional Terms 7.b and 7.c of GPLv3 apply to this file:
* * Requiring preservation of specified reasonable legal notices or
* author attributions in that material or in the Appropriate Legal
* Notices displayed by works containing it.
* * Prohibiting misrepresentation of the origin of that material,
* or requiring that modified versions of such material be marked in
* reasonable ways as different from the original version.
*/
#include "gdb/watchpoints.h"
#include "csvc.h"
#define _REENT_ONLY
#include <errno.h>
/*
There are only 2 Watchpoint Register Pairs on MPCORE ARM11 CPUs,
and only 2 Breakpoint Register Pairs with context ID capabilities (BRP4-5) as well.
We'll reserve and use all 4 of them
*/
RecursiveLock watchpointManagerLock;
typedef struct Watchpoint
{
u32 address;
u32 size;
WatchpointKind kind;
Handle debug; // => context ID
} Watchpoint;
typedef struct WatchpointManager
{
u32 total;
Watchpoint watchpoints[2];
} WatchpointManager;
static WatchpointManager manager;
static void K_EnableMonitorModeDebugging(void)
{
__asm__ __volatile__("cpsid aif");
u32 DSCR;
__asm__ __volatile__("mrc p14, 0, %[val], c0, c1, 0" : [val] "=r" (DSCR));
DSCR |= 0x8000;
__asm__ __volatile__("mcr p14, 0, %[val], c0, c1, 0" :: [val] "r" (DSCR));
}
static void K_DisableWatchpoint(u32 id)
{
u32 control;
__asm__ __volatile__("cpsid aif");
if(id == 0)
{
// WCR0
__asm__ __volatile__("mrc p14, 0, %[val], c0, c0, 7" : [val] "=r" (control));
control &= ~1;
__asm__ __volatile__("mcr p14, 0, %[val], c0, c0, 7" :: [val] "r" (control));
// BCR4
__asm__ __volatile__("mrc p14, 0, %[val], c0, c4, 5" : [val] "=r" (control));
control &= ~1;
__asm__ __volatile__("mcr p14, 0, %[val], c0, c4, 5" :: [val] "r" (control));
}
else if(id == 1)
{
// WCR1
__asm__ __volatile__("mrc p14, 0, %[val], c0, c1, 7" : [val] "=r" (control));
control &= ~1;
__asm__ __volatile__("mcr p14, 0, %[val], c0, c1, 7" :: [val] "r" (control));
// BCR5
__asm__ __volatile__("mrc p14, 0, %[val], c0, c5, 5" : [val] "=r" (control));
control &= ~1;
__asm__ __volatile__("mcr p14, 0, %[val], c0, c5, 5" :: [val] "r" (control));
}
}
static void K_SetWatchpoint0WithContextId(u32 DVA, u32 WCR, u32 contextId)
{
// http://infocenter.arm.com/help/topic/com.arm.doc.ddi0360f/CEGCFFDF.html
u32 BCR =
(1 << 21) | /* compare with context ID */
(1 << 20) | /* linked (with a WRP in our case) */
(0xf << 5) | /* byte address select, +0 to +3 as mandated when linking with a WRP */
(3 << 1) | /* either privileged modes or user mode, as mandated when linking with a WRP */
(1 << 0) ; /* enabled */
__asm__ __volatile__("cpsid aif");
K_DisableWatchpoint(0);
__asm__ __volatile__("mcr p14, 0, %[val], c0, c0, 6" :: [val] "r" (DVA));
__asm__ __volatile__("mcr p14, 0, %[val], c0, c4, 4" :: [val] "r" (contextId));
__asm__ __volatile__("mcr p14, 0, %[val], c0, c0, 7" :: [val] "r" (WCR));
__asm__ __volatile__("mcr p14, 0, %[val], c0, c4, 5" :: [val] "r" (BCR));
__asm__ __volatile__("mcr p15, 0, %[val], c7, c10, 5" :: [val] "r" (0) : "memory"); // DMB
}
static void K_SetWatchpoint1WithContextId(u32 DVA, u32 WCR, u32 contextId)
{
// http://infocenter.arm.com/help/topic/com.arm.doc.ddi0360f/CEGCFFDF.html
u32 BCR =
(1 << 21) | /* compare with context ID */
(1 << 20) | /* linked (with a WRP in our case) */
(0xf << 5) | /* byte address select, +0 to +3 as mandated when linking with a WRP */
(3 << 1) | /* either privileged modes or user mode, as mandated when linking with a WRP */
(1 << 0) ; /* enabled */
__asm__ __volatile__("cpsid aif");
K_DisableWatchpoint(1);
__asm__ __volatile__("mcr p14, 0, %[val], c0, c1, 6" :: [val] "r" (DVA));
__asm__ __volatile__("mcr p14, 0, %[val], c0, c5, 4" :: [val] "r" (contextId));
__asm__ __volatile__("mcr p14, 0, %[val], c0, c1, 7" :: [val] "r" (WCR));
__asm__ __volatile__("mcr p14, 0, %[val], c0, c5, 5" :: [val] "r" (BCR));
__asm__ __volatile__("mcr p15, 0, %[val], c7, c10, 5" :: [val] "r" (0) : "memory"); // DMB
}
void GDB_ResetWatchpoints(void)
{
static bool lockInitialized = false;
if(!lockInitialized)
{
RecursiveLock_Init(&watchpointManagerLock);
lockInitialized = true;
}
RecursiveLock_Lock(&watchpointManagerLock);
svcCustomBackdoor(K_EnableMonitorModeDebugging);
svcCustomBackdoor(K_DisableWatchpoint, 0);
svcCustomBackdoor(K_DisableWatchpoint, 1);
memset(&manager, 0, sizeof(WatchpointManager));
RecursiveLock_Unlock(&watchpointManagerLock);
}
int GDB_AddWatchpoint(GDBContext *ctx, u32 address, u32 size, WatchpointKind kind)
{
RecursiveLock_Lock(&watchpointManagerLock);
u32 offset = address - (address & ~3);
if(manager.total == 2)
return -EBUSY;
if(size == 0 || (offset + size) > 4 || kind == WATCHPOINT_DISABLED)
return -EINVAL;
if(GDB_GetWatchpointKind(ctx, address) != WATCHPOINT_DISABLED)
// Disallow duplicate watchpoints: the kernel doesn't give us sufficient info to differentiate them by kind (DFSR)
return -EINVAL;
u32 id = manager.watchpoints[0].kind == WATCHPOINT_DISABLED ? 0 : 1;
u32 selectMask = ((1 << size) - 1) << offset;
u32 WCR = (1 << 20) | /* linked */
((4 + id) << 16) | /* ID of the linked BRP */
(selectMask << 5) | /* byte address select */
((u32)kind << 3) | /* kind */
(2 << 1) | /* user mode only */
(1 << 0) ; /* enabled */
s64 out;
Result r = svcGetHandleInfo(&out, ctx->debug, 0x10000); // context ID
if(R_SUCCEEDED(r))
{
svcCustomBackdoor(id == 0 ? K_SetWatchpoint0WithContextId : K_SetWatchpoint1WithContextId, address, WCR, (u32)out);
Watchpoint *watchpoint = &manager.watchpoints[id];
manager.total++;
watchpoint->address = address;
watchpoint->size = size;
watchpoint->kind = kind;
watchpoint->debug = ctx->debug;
ctx->watchpoints[ctx->nbWatchpoints++] = address;
RecursiveLock_Unlock(&watchpointManagerLock);
return 0;
}
else
{
RecursiveLock_Unlock(&watchpointManagerLock);
return -EINVAL;
}
}
int GDB_RemoveWatchpoint(GDBContext *ctx, u32 address, WatchpointKind kind)
{
RecursiveLock_Lock(&watchpointManagerLock);
u32 id;
for(id = 0; id < 2 && manager.watchpoints[id].address != address && manager.watchpoints[id].debug != ctx->debug; id++);
if(id == 2 || (kind != WATCHPOINT_DISABLED && manager.watchpoints[id].kind != kind))
{
RecursiveLock_Unlock(&watchpointManagerLock);
return -EINVAL;
}
else
{
svcCustomBackdoor(K_DisableWatchpoint, id);
memset(&manager.watchpoints[id], 0, sizeof(Watchpoint));
manager.total--;
if(ctx->watchpoints[0] == address)
{
ctx->watchpoints[0] = ctx->watchpoints[1];
ctx->watchpoints[1] = 0;
ctx->nbWatchpoints--;
}
else if(ctx->watchpoints[1] == address)
{
ctx->watchpoints[1] = 0;
ctx->nbWatchpoints--;
}
RecursiveLock_Unlock(&watchpointManagerLock);
return 0;
}
}
WatchpointKind GDB_GetWatchpointKind(GDBContext *ctx, u32 address)
{
u32 id;
for(id = 0; id < 2 && manager.watchpoints[id].address != address && manager.watchpoints[id].debug != ctx->debug; id++);
return id == 2 ? WATCHPOINT_DISABLED : manager.watchpoints[id].kind;
}