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/*
* libpulp - User-space Livepatching Library
*
* Copyright (C) 2023 SUSE Software Solutions GmbH
*
* This file is part of libpulp.
*
* libpulp is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* libpulp 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with libpulp. If not, see <http://www.gnu.org/licenses/>.
*/
#include "ulp_common.h"
#include "insn_queue.h"
#include "error_common.h"
#include <assert.h>
#include <stdio.h>
/** @brief Interpret a print instruction.
*
* @param insn Instruction to interpet. Must be a print instruction.
*
* @return Size of interpreted instruction.
*/
int
insn_interpret_print(struct ulp_insn *insn)
{
struct ulp_insn_print *p_insn = (struct ulp_insn_print *)insn;
printf("%s\n", p_insn->bytes);
return insn->size;
}
/** @brief Interpret NOP instruction.
*
* @param insn Instruction to interpet. Must be a NOP instruction.
*
* @return Size of interpreted instruction (always 1 byte).
*/
int
insn_interpret_nop(struct ulp_insn *insn)
{
return sizeof(*insn);
}
/* Writes are specific from libpulp and libpulp-tools:
* - On tools, use ptrace.
* - On libpulp, set text permission and use memcpy.
*/
int
insn_interpret_write(struct ulp_insn *insn);
/** Table of decoders. Index must match the `enum ulp_insn_table` object. */
static int (*decoders[ULP_NUM_INSNS])(struct ulp_insn *insn) = {
insn_interpret_nop,
insn_interpret_print,
insn_interpret_write,
};
/** @brief Interpret the given instruction.
*
* This function will interpret the given instruction.
*
* @param insn Instruction to interpret.
*
* @return Size of instruction interpreted.
*/
int
insn_interpret(struct ulp_insn *insn)
{
int index = (int)insn->type;
return (decoders[index])(insn);
}
/** @brief Interpret the instructions in queue.
*
* Interpret all instructions inserted into the queue object.
*
* @param queue
*/
int
insnq_interpret(insn_queue_t *queue)
{
int pc = 0; /* Like a CPU program counter. */
int num_insns_executed = 0;
int size = queue->size;
int num_insns = queue->num_insns;
char *buffer = queue->buffer;
while (num_insns_executed < num_insns) {
struct ulp_insn *insn = (struct ulp_insn *)&buffer[pc];
if (ulp_insn_valid(insn)) {
pc += insn_interpret(insn);
num_insns_executed++;
}
else {
/* Abort if an invalid insn is received. */
WARN("insnq: invalid insn with opcode %d. Further insns will be "
"ignored.", (int)insn->type);
return EINSNQ;
}
}
/* The pc should stop at the size of the queue. */
if (pc != size) {
WARN("insnq: there are bytes left in the instruction queue");
return EINSNQ;
}
/* Number of instructions should match what is in the queue. */
if (num_insns_executed != num_insns) {
WARN("insnq: not all instructions executed");
return EINSNQ;
}
return 0;
}
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