/* $NetBSD: db_interface.c,v 1.7 2019/01/27 02:08:36 pgoyette Exp $ */
/*
* Copyright (c) 2017 Ryo Shimizu <ryo@nerv.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.7 2019/01/27 02:08:36 pgoyette Exp $");
#include <sys/param.h>
#include <sys/types.h>
#include <uvm/uvm.h>
#include <uvm/uvm_prot.h>
#include <aarch64/db_machdep.h>
#include <aarch64/machdep.h>
#include <aarch64/pmap.h>
#include <aarch64/cpufunc.h>
#include <ddb/db_access.h>
#include <ddb/db_command.h>
#include <ddb/db_output.h>
#include <ddb/db_variables.h>
#include <ddb/db_sym.h>
#include <ddb/db_extern.h>
#include <ddb/db_interface.h>
#include <dev/cons.h>
void
db_read_bytes(vaddr_t addr, size_t size, char *data)
{
vaddr_t lastpage = -1;
const char *src;
for (src = (const char *)addr; size > 0;) {
uintptr_t tmp;
if ((lastpage != atop((vaddr_t)src)) &&
vtophys((vaddr_t)src) == VTOPHYS_FAILED) {
db_printf("address %p is invalid\n", src);
memset(data, 0, size); /* stubs are filled by zero */
return;
}
lastpage = atop((vaddr_t)src);
tmp = (uintptr_t)src | (uintptr_t)data;
if ((size >= 8) && ((tmp & 7) == 0)) {
*(uint64_t *)data = *(const uint64_t *)src;
src += 8;
data += 8;
size -= 8;
} else if ((size >= 4) && ((tmp & 3) == 0)) {
*(uint32_t *)data = *(const uint32_t *)src;
src += 4;
data += 4;
size -= 4;
} else if ((size >= 2) && ((tmp & 1) == 0)) {
*(uint16_t *)data = *(const uint16_t *)src;
src += 2;
data += 2;
size -= 2;
} else {
*data++ = *src++;
size--;
}
}
}
static void
db_write_text(vaddr_t addr, size_t size, const char *data)
{
pt_entry_t *ptep, pte;
size_t s;
/*
* consider page boundary, and
* it works even if kernel_text is mapped with L2 or L3.
*/
if (atop(addr) != atop(addr + size - 1)) {
s = PAGE_SIZE - (addr & PAGE_MASK);
db_write_text(addr, s, data);
addr += s;
size -= s;
data += s;
}
while (size > 0) {
ptep = kvtopte(addr);
KASSERT(ptep != NULL);
/* save pte */
pte = *ptep;
/*
* change to writable. require to keep execute permission.
* because if the block/page to which the target address belongs and
* the block/page to which this function itself belongs are the same,
* if drop PROT_EXECUTE and TLB invalidate, the program stop...
*/
pmap_kvattr(addr, VM_PROT_EXECUTE|VM_PROT_READ|VM_PROT_WRITE);
aarch64_tlbi_all();
s = size;
if (size > PAGE_SIZE)
s = PAGE_SIZE;
memcpy((void *)addr, data, s);
cpu_icache_sync_range(addr, size);
/* restore pte */
*ptep = pte;
aarch64_tlbi_all();
addr += s;
size -= s;
data += s;
}
}
void
db_write_bytes(vaddr_t addr, size_t size, const char *data)
{
vaddr_t kernstart, datastart;
vaddr_t lastpage = -1;
char *dst;
/* if readonly page, require changing attribute to write */
extern char __kernel_text[], __data_start[];
kernstart = trunc_page((vaddr_t)__kernel_text);
datastart = trunc_page((vaddr_t)__data_start);
if (kernstart <= addr && addr < datastart) {
size_t s;
s = datastart - addr;
if (s > size)
s = size;
db_write_text(addr, s, data);
addr += s;
size -= s;
data += s;
}
/* XXX: need to check read only block/page */
for (dst = (char *)addr; size > 0;) {
uintptr_t tmp;
if ((lastpage != atop((vaddr_t)dst)) &&
(vtophys((vaddr_t)dst) == VTOPHYS_FAILED)) {
db_printf("address %p is invalid\n", dst);
return;
}
lastpage = atop((vaddr_t)dst);
tmp = (uintptr_t)dst | (uintptr_t)data;
if ((size >= 8) && ((tmp & 7) == 0)) {
*(uint64_t *)dst = *(const uint64_t *)data;
dst += 8;
data += 8;
size -= 8;
} else if ((size >= 4) && ((tmp & 3) == 0)) {
*(uint32_t *)dst = *(const uint32_t *)data;
dst += 4;
data += 4;
size -= 4;
} else if ((size >= 2) && ((tmp & 1) == 0)) {
*(uint16_t *)dst = *(const uint16_t *)data;
dst += 2;
data += 2;
size -= 2;
} else {
*dst++ = *data++;
size--;
}
}
}
/*
* return register value of $X0..$X30, $SP or 0($XZR)
*/
static uint64_t
db_fetch_reg(unsigned int reg, db_regs_t *regs, bool use_sp)
{
if (reg >= 32)
panic("db_fetch_reg: botch");
if (reg == 31) {
/* $SP or $XZR */
return use_sp ? regs->tf_sp : 0;
}
return regs->tf_reg[reg];
}
static inline uint64_t
SignExtend(int bitwidth, uint64_t imm, unsigned int multiply)
{
const uint64_t signbit = ((uint64_t)1 << (bitwidth - 1));
const uint64_t immmax = signbit << 1;
if (imm & signbit)
imm -= immmax;
return imm * multiply;
}
db_addr_t
db_branch_taken(db_expr_t inst, db_addr_t pc, db_regs_t *regs)
{
#define INSN_FMT_RN(insn) (((insn) >> 5) & 0x1f)
#define INSN_FMT_IMM26(insn) ((insn) & 0x03ffffff)
#define INSN_FMT_IMM19(insn) (((insn) >> 5) & 0x7ffff)
#define INSN_FMT_IMM14(insn) (((insn) >> 5) & 0x3fff)
if (((inst & 0xfffffc1f) == 0xd65f0000) || /* ret xN */
((inst & 0xfffffc1f) == 0xd63f0000) || /* blr xN */
((inst & 0xfffffc1f) == 0xd61f0000)) { /* br xN */
return db_fetch_reg(INSN_FMT_RN(inst), regs, false);
}
if (((inst & 0xfc000000) == 0x94000000) || /* bl imm */
((inst & 0xfc000000) == 0x14000000)) { /* b imm */
return SignExtend(26, INSN_FMT_IMM26(inst), 4) + pc;
}
if (((inst & 0xff000010) == 0x54000000) || /* b.cond */
((inst & 0x7f000000) == 0x35000000) || /* cbnz */
((inst & 0x7f000000) == 0x34000000)) { /* cbz */
return SignExtend(19, INSN_FMT_IMM19(inst), 4) + pc;
}
if (((inst & 0x7f000000) == 0x37000000) || /* tbnz */
((inst & 0x7f000000) == 0x36000000)) { /* tbz */
return SignExtend(14, INSN_FMT_IMM14(inst), 4) + pc;
}
panic("branch_taken: botch");
}
bool
db_inst_unconditional_flow_transfer(db_expr_t inst)
{
if (((inst & 0xfffffc1f) == 0xd65f0000) || /* ret xN */
((inst & 0xfc000000) == 0x94000000) || /* bl */
((inst & 0xfffffc1f) == 0xd63f0000) || /* blr */
((inst & 0xfc000000) == 0x14000000) || /* b imm */
((inst & 0xfffffc1f) == 0xd61f0000)) /* br */
return true;
#define INSN_FMT_COND(insn) ((insn) & 0xf)
#define CONDITION_AL 14
if (((inst & 0xff000010) == 0x54000000) && /* b.cond */
(INSN_FMT_COND(inst) == CONDITION_AL)) /* always? */
return true;
return false;
}