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objtool/LoongArch: Enable orc to be built
Implement arch-specific init_orc_entry(), write_orc_entry(), reg_name(), orc_type_name(), print_reg() and orc_print_dump(), then set BUILD_ORC as y to build the orc related files. Co-developed-by: Jinyang He <hejinyang@loongson.cn> Signed-off-by: Jinyang He <hejinyang@loongson.cn> Co-developed-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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‎tools/arch/loongarch/include/asm/orc_types.h‎

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/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _ORC_TYPES_H
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#define _ORC_TYPES_H
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#include <linux/types.h>
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/*
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* The ORC_REG_* registers are base registers which are used to find other
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* registers on the stack.
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*
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* ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the
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* address of the previous frame: the caller's SP before it called the current
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* function.
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*
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* ORC_REG_UNDEFINED means the corresponding register's value didn't change in
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* the current frame.
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*
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* The most commonly used base registers are SP and FP -- which the previous SP
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* is usually based on -- and PREV_SP and UNDEFINED -- which the previous FP is
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* usually based on.
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*
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* The rest of the base registers are needed for special cases like entry code
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* and GCC realigned stacks.
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*/
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#define ORC_REG_UNDEFINED 0
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#define ORC_REG_PREV_SP 1
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#define ORC_REG_SP 2
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#define ORC_REG_FP 3
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#define ORC_REG_MAX 4
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#define ORC_TYPE_UNDEFINED 0
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#define ORC_TYPE_END_OF_STACK 1
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#define ORC_TYPE_CALL 2
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#define ORC_TYPE_REGS 3
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#define ORC_TYPE_REGS_PARTIAL 4
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#ifndef __ASSEMBLY__
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/*
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* This struct is more or less a vastly simplified version of the DWARF Call
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* Frame Information standard. It contains only the necessary parts of DWARF
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* CFI, simplified for ease of access by the in-kernel unwinder. It tells the
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* unwinder how to find the previous SP and FP (and sometimes entry regs) on
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* the stack for a given code address. Each instance of the struct corresponds
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* to one or more code locations.
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*/
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struct orc_entry {
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s16 sp_offset;
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s16 fp_offset;
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s16 ra_offset;
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unsigned int sp_reg:4;
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unsigned int fp_reg:4;
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unsigned int ra_reg:4;
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unsigned int type:3;
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unsigned int signal:1;
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};
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#endif /* __ASSEMBLY__ */
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#endif /* _ORC_TYPES_H */

‎tools/objtool/Makefile‎

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@@ -57,6 +57,10 @@ ifeq ($(SRCARCH),x86)
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BUILD_ORC := y
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endif
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ifeq ($(SRCARCH),loongarch)
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BUILD_ORC := y
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endif
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export BUILD_ORC
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export srctree OUTPUT CFLAGS SRCARCH AWK
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include $(srctree)/tools/build/Makefile.include

‎tools/objtool/arch/loongarch/Build‎

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objtool-y += decode.o
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objtool-y += special.o
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objtool-y += orc.o

‎tools/objtool/arch/loongarch/decode.c‎

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#include <objtool/check.h>
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#include <objtool/warn.h>
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#include <asm/inst.h>
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#include <asm/orc_types.h>
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#include <linux/objtool_types.h>
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#ifndef EM_LOONGARCH
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#define EM_LOONGARCH 258
@@ -42,6 +44,20 @@ bool arch_callee_saved_reg(unsigned char reg)
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int arch_decode_hint_reg(u8 sp_reg, int *base)
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{
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switch (sp_reg) {
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case ORC_REG_UNDEFINED:
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*base = CFI_UNDEFINED;
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break;
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case ORC_REG_SP:
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*base = CFI_SP;
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break;
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case ORC_REG_FP:
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*base = CFI_FP;
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break;
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default:
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return -1;
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}
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return 0;
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}
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‎tools/objtool/arch/loongarch/orc.c‎

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// SPDX-License-Identifier: GPL-2.0-or-later
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#include <linux/objtool_types.h>
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#include <asm/orc_types.h>
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#include <objtool/check.h>
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#include <objtool/orc.h>
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#include <objtool/warn.h>
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#include <objtool/endianness.h>
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int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi, struct instruction *insn)
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{
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struct cfi_reg *fp = &cfi->regs[CFI_FP];
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struct cfi_reg *ra = &cfi->regs[CFI_RA];
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memset(orc, 0, sizeof(*orc));
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if (!cfi) {
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/*
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* This is usually either unreachable nops/traps (which don't
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* trigger unreachable instruction warnings), or
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* STACK_FRAME_NON_STANDARD functions.
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*/
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orc->type = ORC_TYPE_UNDEFINED;
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return 0;
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}
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switch (cfi->type) {
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case UNWIND_HINT_TYPE_UNDEFINED:
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orc->type = ORC_TYPE_UNDEFINED;
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return 0;
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case UNWIND_HINT_TYPE_END_OF_STACK:
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orc->type = ORC_TYPE_END_OF_STACK;
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return 0;
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case UNWIND_HINT_TYPE_CALL:
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orc->type = ORC_TYPE_CALL;
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break;
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case UNWIND_HINT_TYPE_REGS:
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orc->type = ORC_TYPE_REGS;
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break;
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case UNWIND_HINT_TYPE_REGS_PARTIAL:
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orc->type = ORC_TYPE_REGS_PARTIAL;
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break;
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default:
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WARN_INSN(insn, "unknown unwind hint type %d", cfi->type);
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return -1;
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}
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orc->signal = cfi->signal;
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switch (cfi->cfa.base) {
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case CFI_SP:
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orc->sp_reg = ORC_REG_SP;
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break;
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case CFI_FP:
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orc->sp_reg = ORC_REG_FP;
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break;
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default:
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WARN_INSN(insn, "unknown CFA base reg %d", cfi->cfa.base);
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return -1;
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}
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switch (fp->base) {
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case CFI_UNDEFINED:
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orc->fp_reg = ORC_REG_UNDEFINED;
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orc->fp_offset = 0;
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break;
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case CFI_CFA:
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orc->fp_reg = ORC_REG_PREV_SP;
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orc->fp_offset = fp->offset;
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break;
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case CFI_FP:
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orc->fp_reg = ORC_REG_FP;
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break;
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default:
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WARN_INSN(insn, "unknown FP base reg %d", fp->base);
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return -1;
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}
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switch (ra->base) {
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case CFI_UNDEFINED:
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orc->ra_reg = ORC_REG_UNDEFINED;
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orc->ra_offset = 0;
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break;
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case CFI_CFA:
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orc->ra_reg = ORC_REG_PREV_SP;
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orc->ra_offset = ra->offset;
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break;
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case CFI_FP:
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orc->ra_reg = ORC_REG_FP;
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break;
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default:
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WARN_INSN(insn, "unknown RA base reg %d", ra->base);
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return -1;
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}
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orc->sp_offset = cfi->cfa.offset;
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return 0;
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}
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int write_orc_entry(struct elf *elf, struct section *orc_sec,
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struct section *ip_sec, unsigned int idx,
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struct section *insn_sec, unsigned long insn_off,
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struct orc_entry *o)
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{
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struct orc_entry *orc;
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/* populate ORC data */
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orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
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memcpy(orc, o, sizeof(*orc));
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/* populate reloc for ip */
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if (!elf_init_reloc_text_sym(elf, ip_sec, idx * sizeof(int), idx,
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insn_sec, insn_off))
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return -1;
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return 0;
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}
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static const char *reg_name(unsigned int reg)
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{
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switch (reg) {
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case ORC_REG_SP:
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return "sp";
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case ORC_REG_FP:
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return "fp";
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case ORC_REG_PREV_SP:
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return "prevsp";
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default:
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return "?";
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}
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}
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static const char *orc_type_name(unsigned int type)
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{
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switch (type) {
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case UNWIND_HINT_TYPE_CALL:
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return "call";
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case UNWIND_HINT_TYPE_REGS:
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return "regs";
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case UNWIND_HINT_TYPE_REGS_PARTIAL:
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return "regs (partial)";
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default:
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return "?";
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}
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}
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static void print_reg(unsigned int reg, int offset)
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{
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if (reg == ORC_REG_UNDEFINED)
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printf(" (und) ");
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else
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printf("%s + %3d", reg_name(reg), offset);
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}
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void orc_print_dump(struct elf *dummy_elf, struct orc_entry *orc, int i)
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{
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printf("type:%s", orc_type_name(orc[i].type));
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printf(" sp:");
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print_reg(orc[i].sp_reg, orc[i].sp_offset);
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printf(" fp:");
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print_reg(orc[i].fp_reg, orc[i].fp_offset);
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printf(" ra:");
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print_reg(orc[i].ra_reg, orc[i].ra_offset);
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printf(" signal:%d\n", orc[i].signal);
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}

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