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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012 Rabin Vincent <rabin at rab.in>
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/wait.h>
#include <linux/uprobes.h>
#include <linux/module.h>
#include "../decode.h"
#include "../decode-arm.h"
#include "core.h"
static int uprobes_substitute_pc(unsigned long *pinsn, u32 oregs)
{
probes_opcode_t insn = __mem_to_opcode_arm(*pinsn);
probes_opcode_t temp;
probes_opcode_t mask;
int freereg;
u32 free = 0xffff;
u32 regs;
for (regs = oregs; regs; regs >>= 4, insn >>= 4) {
if ((regs & 0xf) == REG_TYPE_NONE)
continue;
free &= ~(1 << (insn & 0xf));
}
/* No PC, no problem */
if (free & (1 << 15))
return 15;
if (!free)
return -1;
/*
* fls instead of ffs ensures that for "ldrd r0, r1, [pc]" we would
* pick LR instead of R1.
*/
freereg = free = fls(free) - 1;
temp = __mem_to_opcode_arm(*pinsn);
insn = temp;
regs = oregs;
mask = 0xf;
for (; regs; regs >>= 4, mask <<= 4, free <<= 4, temp >>= 4) {
if ((regs & 0xf) == REG_TYPE_NONE)
continue;
if ((temp & 0xf) != 15)
continue;
insn &= ~mask;
insn |= free & mask;
}
*pinsn = __opcode_to_mem_arm(insn);
return freereg;
}
static void uprobe_set_pc(struct arch_uprobe *auprobe,
struct arch_uprobe_task *autask,
struct pt_regs *regs)
{
u32 pcreg = auprobe->pcreg;
autask->backup = regs->uregs[pcreg];
regs->uregs[pcreg] = regs->ARM_pc + 8;
}
static void uprobe_unset_pc(struct arch_uprobe *auprobe,
struct arch_uprobe_task *autask,
struct pt_regs *regs)
{
/* PC will be taken care of by common code */
regs->uregs[auprobe->pcreg] = autask->backup;
}
static void uprobe_aluwrite_pc(struct arch_uprobe *auprobe,
struct arch_uprobe_task *autask,
struct pt_regs *regs)
{
u32 pcreg = auprobe->pcreg;
alu_write_pc(regs->uregs[pcreg], regs);
regs->uregs[pcreg] = autask->backup;
}
static void uprobe_write_pc(struct arch_uprobe *auprobe,
struct arch_uprobe_task *autask,
struct pt_regs *regs)
{
u32 pcreg = auprobe->pcreg;
load_write_pc(regs->uregs[pcreg], regs);
regs->uregs[pcreg] = autask->backup;
}
enum probes_insn
decode_pc_ro(probes_opcode_t insn, struct arch_probes_insn *asi,
const struct decode_header *d)
{
struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
asi);
struct decode_emulate *decode = (struct decode_emulate *) d;
u32 regs = decode->header.type_regs.bits >> DECODE_TYPE_BITS;
int reg;
reg = uprobes_substitute_pc(&auprobe->ixol[0], regs);
if (reg == 15)
return INSN_GOOD;
if (reg == -1)
return INSN_REJECTED;
auprobe->pcreg = reg;
auprobe->prehandler = uprobe_set_pc;
auprobe->posthandler = uprobe_unset_pc;
return INSN_GOOD;
}
enum probes_insn
decode_wb_pc(probes_opcode_t insn, struct arch_probes_insn *asi,
const struct decode_header *d, bool alu)
{
struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
asi);
enum probes_insn ret = decode_pc_ro(insn, asi, d);
if (((insn >> 12) & 0xf) == 15)
auprobe->posthandler = alu ? uprobe_aluwrite_pc
: uprobe_write_pc;
return ret;
}
enum probes_insn
decode_rd12rn16rm0rs8_rwflags(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *d)
{
return decode_wb_pc(insn, asi, d, true);
}
enum probes_insn
decode_ldr(probes_opcode_t insn, struct arch_probes_insn *asi,
const struct decode_header *d)
{
return decode_wb_pc(insn, asi, d, false);
}
enum probes_insn
uprobe_decode_ldmstm(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *d)
{
struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
asi);
unsigned reglist = insn & 0xffff;
int rn = (insn >> 16) & 0xf;
int lbit = insn & (1 << 20);
unsigned used = reglist | (1 << rn);
if (rn == 15)
return INSN_REJECTED;
if (!(used & (1 << 15)))
return INSN_GOOD;
if (used & (1 << 14))
return INSN_REJECTED;
/* Use LR instead of PC */
insn ^= 0xc000;
auprobe->pcreg = 14;
auprobe->ixol[0] = __opcode_to_mem_arm(insn);
auprobe->prehandler = uprobe_set_pc;
if (lbit)
auprobe->posthandler = uprobe_write_pc;
else
auprobe->posthandler = uprobe_unset_pc;
return INSN_GOOD;
}
const union decode_action uprobes_probes_actions[] = {
[PROBES_PRELOAD_IMM] = {.handler = probes_simulate_nop},
[PROBES_PRELOAD_REG] = {.handler = probes_simulate_nop},
[PROBES_BRANCH_IMM] = {.handler = simulate_blx1},
[PROBES_MRS] = {.handler = simulate_mrs},
[PROBES_BRANCH_REG] = {.handler = simulate_blx2bx},
[PROBES_CLZ] = {.handler = probes_simulate_nop},
[PROBES_SATURATING_ARITHMETIC] = {.handler = probes_simulate_nop},
[PROBES_MUL1] = {.handler = probes_simulate_nop},
[PROBES_MUL2] = {.handler = probes_simulate_nop},
[PROBES_SWP] = {.handler = probes_simulate_nop},
[PROBES_LDRSTRD] = {.decoder = decode_pc_ro},
[PROBES_LOAD_EXTRA] = {.decoder = decode_pc_ro},
[PROBES_LOAD] = {.decoder = decode_ldr},
[PROBES_STORE_EXTRA] = {.decoder = decode_pc_ro},
[PROBES_STORE] = {.decoder = decode_pc_ro},
[PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp},
[PROBES_DATA_PROCESSING_REG] = {
.decoder = decode_rd12rn16rm0rs8_rwflags},
[PROBES_DATA_PROCESSING_IMM] = {
.decoder = decode_rd12rn16rm0rs8_rwflags},
[PROBES_MOV_HALFWORD] = {.handler = probes_simulate_nop},
[PROBES_SEV] = {.handler = probes_simulate_nop},
[PROBES_WFE] = {.handler = probes_simulate_nop},
[PROBES_SATURATE] = {.handler = probes_simulate_nop},
[PROBES_REV] = {.handler = probes_simulate_nop},
[PROBES_MMI] = {.handler = probes_simulate_nop},
[PROBES_PACK] = {.handler = probes_simulate_nop},
[PROBES_EXTEND] = {.handler = probes_simulate_nop},
[PROBES_EXTEND_ADD] = {.handler = probes_simulate_nop},
[PROBES_MUL_ADD_LONG] = {.handler = probes_simulate_nop},
[PROBES_MUL_ADD] = {.handler = probes_simulate_nop},
[PROBES_BITFIELD] = {.handler = probes_simulate_nop},
[PROBES_BRANCH] = {.handler = simulate_bbl},
[PROBES_LDMSTM] = {.decoder = uprobe_decode_ldmstm}
};
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