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Diffstat (limited to 'tools/objtool/arch/x86/decode.c')
-rw-r--r--tools/objtool/arch/x86/decode.c318
1 files changed, 230 insertions, 88 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index e7b030f7e2a5..f4af82508228 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -16,14 +16,22 @@
#include <asm/orc_types.h>
#include <objtool/check.h>
+#include <objtool/disas.h>
#include <objtool/elf.h>
#include <objtool/arch.h>
#include <objtool/warn.h>
-#include <objtool/endianness.h>
#include <objtool/builtin.h>
#include <arch/elf.h>
-int arch_ftrace_match(char *name)
+const char *arch_reg_name[CFI_NUM_REGS] = {
+ "rax", "rcx", "rdx", "rbx",
+ "rsp", "rbp", "rsi", "rdi",
+ "r8", "r9", "r10", "r11",
+ "r12", "r13", "r14", "r15",
+ "ra"
+};
+
+int arch_ftrace_match(const char *name)
{
return !strcmp(name, "__fentry__");
}
@@ -36,7 +44,7 @@ static int is_x86_64(const struct elf *elf)
case EM_386:
return 0;
default:
- WARN("unexpected ELF machine type %d", elf->ehdr.e_machine);
+ ERROR("unexpected ELF machine type %d", elf->ehdr.e_machine);
return -1;
}
}
@@ -68,9 +76,65 @@ bool arch_callee_saved_reg(unsigned char reg)
}
}
-unsigned long arch_dest_reloc_offset(int addend)
+/* Undo the effects of __pa_symbol() if necessary */
+static unsigned long phys_to_virt(unsigned long pa)
+{
+ s64 va = pa;
+
+ if (va > 0)
+ va &= ~(0x80000000);
+
+ return va;
+}
+
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
+{
+ s64 addend = reloc_addend(reloc);
+
+ if (arch_pc_relative_reloc(reloc))
+ addend += insn->offset + insn->len - reloc_offset(reloc);
+
+ return phys_to_virt(addend);
+}
+
+static void scan_for_insn(struct section *sec, unsigned long offset,
+ unsigned long *insn_off, unsigned int *insn_len)
+{
+ unsigned long o = 0;
+ struct insn insn;
+
+ while (1) {
+
+ insn_decode(&insn, sec->data->d_buf + o, sec_size(sec) - o,
+ INSN_MODE_64);
+
+ if (o + insn.length > offset) {
+ *insn_off = o;
+ *insn_len = insn.length;
+ return;
+ }
+
+ o += insn.length;
+ }
+}
+
+u64 arch_adjusted_addend(struct reloc *reloc)
{
- return addend + 4;
+ unsigned int type = reloc_type(reloc);
+ s64 addend = reloc_addend(reloc);
+ unsigned long insn_off;
+ unsigned int insn_len;
+
+ if (type == R_X86_64_PLT32)
+ return addend + 4;
+
+ if (type != R_X86_64_PC32 || !is_text_sec(reloc->sec->base))
+ return addend;
+
+ scan_for_insn(reloc->sec->base, reloc_offset(reloc),
+ &insn_off, &insn_len);
+
+ return addend + insn_off + insn_len - reloc_offset(reloc);
}
unsigned long arch_jump_destination(struct instruction *insn)
@@ -84,7 +148,7 @@ bool arch_pc_relative_reloc(struct reloc *reloc)
* All relocation types where P (the address of the target)
* is included in the computation.
*/
- switch (reloc->type) {
+ switch (reloc_type(reloc)) {
case R_X86_64_PC8:
case R_X86_64_PC16:
case R_X86_64_PC32:
@@ -105,7 +169,7 @@ bool arch_pc_relative_reloc(struct reloc *reloc)
#define ADD_OP(op) \
if (!(op = calloc(1, sizeof(*op)))) \
return -1; \
- else for (list_add_tail(&op->list, ops_list); op; op = NULL)
+ else for (*ops_list = op, ops_list = &op->next; op; op = NULL)
/*
* Helpers to decode ModRM/SIB:
@@ -125,8 +189,14 @@ bool arch_pc_relative_reloc(struct reloc *reloc)
#define is_RIP() ((modrm_rm & 7) == CFI_BP && modrm_mod == 0)
#define have_SIB() ((modrm_rm & 7) == CFI_SP && mod_is_mem())
+/*
+ * Check the ModRM register. If there is a SIB byte then check with
+ * the SIB base register. But if the SIB base is 5 (i.e. CFI_BP) and
+ * ModRM mod is 0 then there is no base register.
+ */
#define rm_is(reg) (have_SIB() ? \
- sib_base == (reg) && sib_index == CFI_SP : \
+ sib_base == (reg) && sib_index == CFI_SP && \
+ (sib_base != CFI_BP || modrm_mod != 0) : \
modrm_rm == (reg))
#define rm_is_mem(reg) (mod_is_mem() && !is_RIP() && rm_is(reg))
@@ -146,12 +216,11 @@ static bool has_notrack_prefix(struct insn *insn)
int arch_decode_instruction(struct objtool_file *file, const struct section *sec,
unsigned long offset, unsigned int maxlen,
- unsigned int *len, enum insn_type *type,
- unsigned long *immediate,
- struct list_head *ops_list)
+ struct instruction *insn)
{
+ struct stack_op **ops_list = &insn->stack_ops;
const struct elf *elf = file->elf;
- struct insn insn;
+ struct insn ins;
int x86_64, ret;
unsigned char op1, op2, op3, prefix,
rex = 0, rex_b = 0, rex_r = 0, rex_w = 0, rex_x = 0,
@@ -165,42 +234,42 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
if (x86_64 == -1)
return -1;
- ret = insn_decode(&insn, sec->data->d_buf + offset, maxlen,
+ ret = insn_decode(&ins, sec->data->d_buf + offset, maxlen,
x86_64 ? INSN_MODE_64 : INSN_MODE_32);
if (ret < 0) {
- WARN("can't decode instruction at %s:0x%lx", sec->name, offset);
+ ERROR("can't decode instruction at %s:0x%lx", sec->name, offset);
return -1;
}
- *len = insn.length;
- *type = INSN_OTHER;
+ insn->len = ins.length;
+ insn->type = INSN_OTHER;
- if (insn.vex_prefix.nbytes)
+ if (ins.vex_prefix.nbytes)
return 0;
- prefix = insn.prefixes.bytes[0];
+ prefix = ins.prefixes.bytes[0];
- op1 = insn.opcode.bytes[0];
- op2 = insn.opcode.bytes[1];
- op3 = insn.opcode.bytes[2];
+ op1 = ins.opcode.bytes[0];
+ op2 = ins.opcode.bytes[1];
+ op3 = ins.opcode.bytes[2];
- if (insn.rex_prefix.nbytes) {
- rex = insn.rex_prefix.bytes[0];
+ if (ins.rex_prefix.nbytes) {
+ rex = ins.rex_prefix.bytes[0];
rex_w = X86_REX_W(rex) >> 3;
rex_r = X86_REX_R(rex) >> 2;
rex_x = X86_REX_X(rex) >> 1;
rex_b = X86_REX_B(rex);
}
- if (insn.modrm.nbytes) {
- modrm = insn.modrm.bytes[0];
+ if (ins.modrm.nbytes) {
+ modrm = ins.modrm.bytes[0];
modrm_mod = X86_MODRM_MOD(modrm);
modrm_reg = X86_MODRM_REG(modrm) + 8*rex_r;
modrm_rm = X86_MODRM_RM(modrm) + 8*rex_b;
}
- if (insn.sib.nbytes) {
- sib = insn.sib.bytes[0];
+ if (ins.sib.nbytes) {
+ sib = ins.sib.bytes[0];
/* sib_scale = X86_SIB_SCALE(sib); */
sib_index = X86_SIB_INDEX(sib) + 8*rex_x;
sib_base = X86_SIB_BASE(sib) + 8*rex_b;
@@ -254,7 +323,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
break;
case 0x70 ... 0x7f:
- *type = INSN_JUMP_CONDITIONAL;
+ insn->type = INSN_JUMP_CONDITIONAL;
break;
case 0x80 ... 0x83:
@@ -278,7 +347,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
if (!rm_is_reg(CFI_SP))
break;
- imm = insn.immediate.value;
+ imm = ins.immediate.value;
if (op1 & 2) { /* sign extend */
if (op1 & 1) { /* imm32 */
imm <<= 32;
@@ -292,7 +361,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
switch (modrm_reg & 7) {
case 5:
imm = -imm;
- /* fallthrough */
+ fallthrough;
case 0:
/* add/sub imm, %rsp */
ADD_OP(op) {
@@ -309,14 +378,14 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
ADD_OP(op) {
op->src.type = OP_SRC_AND;
op->src.reg = CFI_SP;
- op->src.offset = insn.immediate.value;
+ op->src.offset = ins.immediate.value;
op->dest.type = OP_DEST_REG;
op->dest.reg = CFI_SP;
}
break;
default:
- /* WARN ? */
+ /* ERROR ? */
break;
}
@@ -356,7 +425,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
op->src.reg = CFI_SP;
op->dest.type = OP_DEST_REG_INDIRECT;
op->dest.reg = modrm_rm;
- op->dest.offset = insn.displacement.value;
+ op->dest.offset = ins.displacement.value;
}
break;
}
@@ -376,7 +445,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
break;
}
- /* fallthrough */
+ fallthrough;
case 0x88:
if (!rex_w)
break;
@@ -389,7 +458,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
op->src.reg = modrm_reg;
op->dest.type = OP_DEST_REG_INDIRECT;
op->dest.reg = CFI_BP;
- op->dest.offset = insn.displacement.value;
+ op->dest.offset = ins.displacement.value;
}
break;
}
@@ -402,7 +471,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
op->src.reg = modrm_reg;
op->dest.type = OP_DEST_REG_INDIRECT;
op->dest.reg = CFI_SP;
- op->dest.offset = insn.displacement.value;
+ op->dest.offset = ins.displacement.value;
}
break;
}
@@ -419,7 +488,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
ADD_OP(op) {
op->src.type = OP_SRC_REG_INDIRECT;
op->src.reg = CFI_BP;
- op->src.offset = insn.displacement.value;
+ op->src.offset = ins.displacement.value;
op->dest.type = OP_DEST_REG;
op->dest.reg = modrm_reg;
}
@@ -432,7 +501,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
ADD_OP(op) {
op->src.type = OP_SRC_REG_INDIRECT;
op->src.reg = CFI_SP;
- op->src.offset = insn.displacement.value;
+ op->src.offset = ins.displacement.value;
op->dest.type = OP_DEST_REG;
op->dest.reg = modrm_reg;
}
@@ -451,10 +520,6 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
if (!rex_w)
break;
- /* skip RIP relative displacement */
- if (is_RIP())
- break;
-
/* skip nontrivial SIB */
if (have_SIB()) {
modrm_rm = sib_base;
@@ -462,9 +527,15 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
break;
}
+ /* lea disp(%rip), %dst */
+ if (is_RIP()) {
+ insn->type = INSN_LEA_RIP;
+ break;
+ }
+
/* lea disp(%src), %dst */
ADD_OP(op) {
- op->src.offset = insn.displacement.value;
+ op->src.offset = ins.displacement.value;
if (!op->src.offset) {
/* lea (%src), %dst */
op->src.type = OP_SRC_REG;
@@ -487,7 +558,13 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
break;
case 0x90:
- *type = INSN_NOP;
+ if (rex_b) /* XCHG %r8, %rax */
+ break;
+
+ if (prefix == 0xf3) /* REP NOP := PAUSE */
+ break;
+
+ insn->type = INSN_NOP;
break;
case 0x9c:
@@ -510,43 +587,56 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
if (op2 == 0x01) {
- if (modrm == 0xca)
- *type = INSN_CLAC;
- else if (modrm == 0xcb)
- *type = INSN_STAC;
-
+ switch (insn_last_prefix_id(&ins)) {
+ case INAT_PFX_REPE:
+ case INAT_PFX_REPNE:
+ if (modrm == 0xca)
+ /* eretu/erets */
+ insn->type = INSN_SYSRET;
+ break;
+ default:
+ if (modrm == 0xca)
+ insn->type = INSN_CLAC;
+ else if (modrm == 0xcb)
+ insn->type = INSN_STAC;
+ break;
+ }
} else if (op2 >= 0x80 && op2 <= 0x8f) {
- *type = INSN_JUMP_CONDITIONAL;
+ insn->type = INSN_JUMP_CONDITIONAL;
+
+ } else if (op2 == 0x05 || op2 == 0x34) {
+
+ /* syscall, sysenter */
+ insn->type = INSN_SYSCALL;
- } else if (op2 == 0x05 || op2 == 0x07 || op2 == 0x34 ||
- op2 == 0x35) {
+ } else if (op2 == 0x07 || op2 == 0x35) {
- /* sysenter, sysret */
- *type = INSN_CONTEXT_SWITCH;
+ /* sysret, sysexit */
+ insn->type = INSN_SYSRET;
} else if (op2 == 0x0b || op2 == 0xb9) {
- /* ud2 */
- *type = INSN_BUG;
+ /* ud2, ud1 */
+ insn->type = INSN_BUG;
- } else if (op2 == 0x0d || op2 == 0x1f) {
+ } else if (op2 == 0x1f) {
- /* nopl/nopw */
- *type = INSN_NOP;
+ /* 0f 1f /0 := NOPL */
+ if (modrm_reg == 0)
+ insn->type = INSN_NOP;
} else if (op2 == 0x1e) {
if (prefix == 0xf3 && (modrm == 0xfa || modrm == 0xfb))
- *type = INSN_ENDBR;
+ insn->type = INSN_ENDBR;
} else if (op2 == 0x38 && op3 == 0xf8) {
- if (insn.prefixes.nbytes == 1 &&
- insn.prefixes.bytes[0] == 0xf2) {
+ if (ins.prefixes.nbytes == 1 &&
+ ins.prefixes.bytes[0] == 0xf2) {
/* ENQCMD cannot be used in the kernel. */
- WARN("ENQCMD instruction at %s:%lx", sec->name,
- offset);
+ WARN("ENQCMD instruction at %s:%lx", sec->name, offset);
}
} else if (op2 == 0xa0 || op2 == 0xa8) {
@@ -591,29 +681,29 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
case 0xcc:
/* int3 */
- *type = INSN_TRAP;
+ insn->type = INSN_TRAP;
break;
case 0xe3:
/* jecxz/jrcxz */
- *type = INSN_JUMP_CONDITIONAL;
+ insn->type = INSN_JUMP_CONDITIONAL;
break;
case 0xe9:
case 0xeb:
- *type = INSN_JUMP_UNCONDITIONAL;
+ insn->type = INSN_JUMP_UNCONDITIONAL;
break;
case 0xc2:
case 0xc3:
- *type = INSN_RETURN;
+ insn->type = INSN_RETURN;
break;
case 0xc7: /* mov imm, r/m */
if (!opts.noinstr)
break;
- if (insn.length == 3+4+4 && !strncmp(sec->name, ".init.text", 10)) {
+ if (ins.length == 3+4+4 && !strncmp(sec->name, ".init.text", 10)) {
struct reloc *immr, *disp;
struct symbol *func;
int idx;
@@ -624,13 +714,13 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
if (!immr || strcmp(immr->sym->name, "pv_ops"))
break;
- idx = (immr->addend + 8) / sizeof(void *);
+ idx = (reloc_addend(immr) + 8) / sizeof(void *);
func = disp->sym;
if (disp->sym->type == STT_SECTION)
- func = find_symbol_by_offset(disp->sym->sec, disp->addend);
+ func = find_symbol_by_offset(disp->sym->sec, reloc_addend(disp));
if (!func) {
- WARN("no func for pv_ops[]");
+ ERROR("no func for pv_ops[]");
return -1;
}
@@ -657,21 +747,25 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
break;
}
- /* fallthrough */
+ fallthrough;
case 0xca: /* retf */
case 0xcb: /* retf */
- *type = INSN_CONTEXT_SWITCH;
+ insn->type = INSN_SYSRET;
+ break;
+
+ case 0xd6: /* udb */
+ insn->type = INSN_BUG;
break;
case 0xe0: /* loopne */
case 0xe1: /* loope */
case 0xe2: /* loop */
- *type = INSN_JUMP_CONDITIONAL;
+ insn->type = INSN_JUMP_CONDITIONAL;
break;
case 0xe8:
- *type = INSN_CALL;
+ insn->type = INSN_CALL;
/*
* For the impact on the stack, a CALL behaves like
* a PUSH of an immediate value (the return address).
@@ -683,30 +777,30 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
break;
case 0xfc:
- *type = INSN_CLD;
+ insn->type = INSN_CLD;
break;
case 0xfd:
- *type = INSN_STD;
+ insn->type = INSN_STD;
break;
case 0xff:
if (modrm_reg == 2 || modrm_reg == 3) {
- *type = INSN_CALL_DYNAMIC;
- if (has_notrack_prefix(&insn))
+ insn->type = INSN_CALL_DYNAMIC;
+ if (has_notrack_prefix(&ins))
WARN("notrack prefix found at %s:0x%lx", sec->name, offset);
} else if (modrm_reg == 4) {
- *type = INSN_JUMP_DYNAMIC;
- if (has_notrack_prefix(&insn))
+ insn->type = INSN_JUMP_DYNAMIC;
+ if (has_notrack_prefix(&ins))
WARN("notrack prefix found at %s:0x%lx", sec->name, offset);
} else if (modrm_reg == 5) {
/* jmpf */
- *type = INSN_CONTEXT_SWITCH;
+ insn->type = INSN_SYSRET;
} else if (modrm_reg == 6) {
@@ -723,7 +817,10 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
break;
}
- *immediate = insn.immediate.nbytes ? insn.immediate.value : 0;
+ if (ins.immediate.nbytes)
+ insn->immediate = ins.immediate.value;
+ else if (ins.displacement.nbytes)
+ insn->immediate = ins.displacement.value;
return 0;
}
@@ -757,7 +854,7 @@ const char *arch_nop_insn(int len)
};
if (len < 1 || len > 5) {
- WARN("invalid NOP size: %d\n", len);
+ ERROR("invalid NOP size: %d\n", len);
return NULL;
}
@@ -777,7 +874,7 @@ const char *arch_ret_insn(int len)
};
if (len < 1 || len > 5) {
- WARN("invalid RET size: %d\n", len);
+ ERROR("invalid RET size: %d\n", len);
return NULL;
}
@@ -820,10 +917,55 @@ int arch_decode_hint_reg(u8 sp_reg, int *base)
bool arch_is_retpoline(struct symbol *sym)
{
- return !strncmp(sym->name, "__x86_indirect_", 15);
+ return !strncmp(sym->name, "__x86_indirect_", 15) ||
+ !strncmp(sym->name, "__pi___x86_indirect_", 20);
}
bool arch_is_rethunk(struct symbol *sym)
{
- return !strcmp(sym->name, "__x86_return_thunk");
+ return !strcmp(sym->name, "__x86_return_thunk") ||
+ !strcmp(sym->name, "__pi___x86_return_thunk");
+}
+
+bool arch_is_embedded_insn(struct symbol *sym)
+{
+ return !strcmp(sym->name, "retbleed_return_thunk") ||
+ !strcmp(sym->name, "srso_alias_safe_ret") ||
+ !strcmp(sym->name, "srso_safe_ret");
}
+
+unsigned int arch_reloc_size(struct reloc *reloc)
+{
+ switch (reloc_type(reloc)) {
+ case R_X86_64_32:
+ case R_X86_64_32S:
+ case R_X86_64_PC32:
+ case R_X86_64_PLT32:
+ return 4;
+ default:
+ return 8;
+ }
+}
+
+bool arch_absolute_reloc(struct elf *elf, struct reloc *reloc)
+{
+ switch (reloc_type(reloc)) {
+ case R_X86_64_32:
+ case R_X86_64_32S:
+ case R_X86_64_64:
+ return true;
+ default:
+ return false;
+ }
+}
+
+#ifdef DISAS
+
+int arch_disas_info_init(struct disassemble_info *dinfo)
+{
+ return disas_info_init(dinfo, bfd_arch_i386,
+ bfd_mach_i386_i386, bfd_mach_x86_64,
+ "att");
+}
+
+#endif /* DISAS */
generated by cgit (git 2.34.1) at 2025-12-21 20:40:33 +0000