unwind-libdw.c

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// SPDX-License-Identifier: GPL-2.0
#include <elfutils/libdwfl.h>
#include "../../util/unwind-libdw.h"
#include "../../util/perf_regs.h"
#include "../../util/event.h"

/* See backends/ppc_initreg.c and backends/ppc_regs.c in elfutils.  */
static const int special_regs[3][2] = {
    { 65, PERF_REG_POWERPC_LINK },
    { 101, PERF_REG_POWERPC_XER },
    { 109, PERF_REG_POWERPC_CTR },
};

bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
{
    struct unwind_info *ui = arg;
    struct regs_dump *user_regs = &ui->sample->user_regs;
    Dwarf_Word dwarf_regs[32], dwarf_nip;
    size_t i;

#define REG(r) ({                       \
    Dwarf_Word val = 0;                 \
    perf_reg_value(&val, user_regs, PERF_REG_POWERPC_##r);  \
    val;                            \
})

    dwarf_regs[0]  = REG(R0);
    dwarf_regs[1]  = REG(R1);
    dwarf_regs[2]  = REG(R2);
    dwarf_regs[3]  = REG(R3);
    dwarf_regs[4]  = REG(R4);
    dwarf_regs[5]  = REG(R5);
    dwarf_regs[6]  = REG(R6);
    dwarf_regs[7]  = REG(R7);
    dwarf_regs[8]  = REG(R8);
    dwarf_regs[9]  = REG(R9);
    dwarf_regs[10] = REG(R10);
    dwarf_regs[11] = REG(R11);
    dwarf_regs[12] = REG(R12);
    dwarf_regs[13] = REG(R13);
    dwarf_regs[14] = REG(R14);
    dwarf_regs[15] = REG(R15);
    dwarf_regs[16] = REG(R16);
    dwarf_regs[17] = REG(R17);
    dwarf_regs[18] = REG(R18);
    dwarf_regs[19] = REG(R19);
    dwarf_regs[20] = REG(R20);
    dwarf_regs[21] = REG(R21);
    dwarf_regs[22] = REG(R22);
    dwarf_regs[23] = REG(R23);
    dwarf_regs[24] = REG(R24);
    dwarf_regs[25] = REG(R25);
    dwarf_regs[26] = REG(R26);
    dwarf_regs[27] = REG(R27);
    dwarf_regs[28] = REG(R28);
    dwarf_regs[29] = REG(R29);
    dwarf_regs[30] = REG(R30);
    dwarf_regs[31] = REG(R31);
    if (!dwfl_thread_state_registers(thread, 0, 32, dwarf_regs))
        return false;

    dwarf_nip = REG(NIP);
    dwfl_thread_state_register_pc(thread, dwarf_nip);
    for (i = 0; i < ARRAY_SIZE(special_regs); i++) {
        Dwarf_Word val = 0;
        perf_reg_value(&val, user_regs, special_regs[i][1]);
        if (!dwfl_thread_state_registers(thread,
                         special_regs[i][0], 1,
                         &val))
            return false;
    }

    return true;
}