[RFC PATCH v0 03/19] x86/insn: Add an insn_decode() API
From: Borislav Petkov
Date: Tue Nov 24 2020 - 05:21:13 EST
From: Borislav Petkov <bp@xxxxxxx>
Users of the instruction decoder should use this to decode instruction
bytes. For that, have insn*() helpers return an int value to denote
success/failure.
While at it, make insn_get_opcode() more stricter as to whether what has
seen so far is a valid insn and if not.
Copy linux/kconfig.h for the tools-version of the decoder so that it can
use IS_ENABLED().
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
arch/x86/include/asm/insn.h | 24 ++--
arch/x86/lib/insn.c | 182 +++++++++++++++++++++++-------
tools/arch/x86/include/asm/insn.h | 24 ++--
tools/arch/x86/lib/insn.c | 182 +++++++++++++++++++++++-------
tools/include/linux/kconfig.h | 73 ++++++++++++
5 files changed, 391 insertions(+), 94 deletions(-)
create mode 100644 tools/include/linux/kconfig.h
diff --git a/arch/x86/include/asm/insn.h b/arch/x86/include/asm/insn.h
index 5c1ae3eff9d4..e80ddfe86255 100644
--- a/arch/x86/include/asm/insn.h
+++ b/arch/x86/include/asm/insn.h
@@ -87,13 +87,23 @@ struct insn {
#define X86_VEX_M_MAX 0x1f /* VEX3.M Maximum value */
extern void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64);
-extern void insn_get_prefixes(struct insn *insn);
-extern void insn_get_opcode(struct insn *insn);
-extern void insn_get_modrm(struct insn *insn);
-extern void insn_get_sib(struct insn *insn);
-extern void insn_get_displacement(struct insn *insn);
-extern void insn_get_immediate(struct insn *insn);
-extern void insn_get_length(struct insn *insn);
+extern int insn_get_prefixes(struct insn *insn);
+extern int insn_get_opcode(struct insn *insn);
+extern int insn_get_modrm(struct insn *insn);
+extern int insn_get_sib(struct insn *insn);
+extern int insn_get_displacement(struct insn *insn);
+extern int insn_get_immediate(struct insn *insn);
+extern int insn_get_length(struct insn *insn);
+
+enum insn_mode {
+ INSN_MODE_32,
+ INSN_MODE_64,
+ /* Mode is determined by the current kernel build. */
+ INSN_MODE_KERN,
+ INSN_NUM_MODES,
+};
+
+extern int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m);
/* Attribute will be determined after getting ModRM (for opcode groups) */
static inline void insn_get_attribute(struct insn *insn)
diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
index 1ba994862b56..1f749e3b4a25 100644
--- a/arch/x86/lib/insn.c
+++ b/arch/x86/lib/insn.c
@@ -13,6 +13,9 @@
#include <asm/inat.h>
#include <asm/insn.h>
+#include <linux/errno.h>
+#include <linux/kconfig.h>
+
#include <asm/emulate_prefix.h>
/* Verify next sizeof(t) bytes can be on the same instruction */
@@ -98,8 +101,12 @@ static void insn_get_emulate_prefix(struct insn *insn)
* Populates the @insn->prefixes bitmap, and updates @insn->next_byte
* to point to the (first) opcode. No effect if @insn->prefixes.got
* is already set.
+ *
+ * * Returns:
+ * 0: on success
+ * !0: on error
*/
-void insn_get_prefixes(struct insn *insn)
+int insn_get_prefixes(struct insn *insn)
{
struct insn_field *prefixes = &insn->prefixes;
insn_attr_t attr;
@@ -107,7 +114,7 @@ void insn_get_prefixes(struct insn *insn)
int i, nb;
if (prefixes->got)
- return;
+ return 0;
insn_get_emulate_prefix(insn);
@@ -218,8 +225,10 @@ void insn_get_prefixes(struct insn *insn)
prefixes->got = 1;
+ return 0;
+
err_out:
- return;
+ return 1;
}
/**
@@ -231,14 +240,20 @@ void insn_get_prefixes(struct insn *insn)
* If necessary, first collects any preceding (prefix) bytes.
* Sets @insn->opcode.value = opcode1. No effect if @insn->opcode.got
* is already 1.
+ *
+ * Returns:
+ * 0: on success
+ * !0: on error
*/
-void insn_get_opcode(struct insn *insn)
+int insn_get_opcode(struct insn *insn)
{
struct insn_field *opcode = &insn->opcode;
insn_byte_t op;
int pfx_id;
+
if (opcode->got)
- return;
+ return 0;
+
if (!insn->prefixes.got)
insn_get_prefixes(insn);
@@ -255,9 +270,13 @@ void insn_get_opcode(struct insn *insn)
insn->attr = inat_get_avx_attribute(op, m, p);
if ((inat_must_evex(insn->attr) && !insn_is_evex(insn)) ||
(!inat_accept_vex(insn->attr) &&
- !inat_is_group(insn->attr)))
- insn->attr = 0; /* This instruction is bad */
- goto end; /* VEX has only 1 byte for opcode */
+ !inat_is_group(insn->attr))) {
+ /* This instruction is bad */
+ insn->attr = 0;
+ return 1;
+ }
+ /* VEX has only 1 byte for opcode */
+ goto end;
}
insn->attr = inat_get_opcode_attribute(op);
@@ -268,13 +287,18 @@ void insn_get_opcode(struct insn *insn)
pfx_id = insn_last_prefix_id(insn);
insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
}
- if (inat_must_vex(insn->attr))
- insn->attr = 0; /* This instruction is bad */
+
+ if (inat_must_vex(insn->attr)) {
+ /* This instruction is bad */
+ insn->attr = 0;
+ return 1;
+ }
end:
opcode->got = 1;
+ return 0;
err_out:
- return;
+ return 1;
}
/**
@@ -284,15 +308,22 @@ void insn_get_opcode(struct insn *insn)
* Populates @insn->modrm and updates @insn->next_byte to point past the
* ModRM byte, if any. If necessary, first collects the preceding bytes
* (prefixes and opcode(s)). No effect if @insn->modrm.got is already 1.
+ *
+ * Returns:
+ * 0: on success
+ * !0: on error
*/
-void insn_get_modrm(struct insn *insn)
+int insn_get_modrm(struct insn *insn)
{
struct insn_field *modrm = &insn->modrm;
insn_byte_t pfx_id, mod;
+
if (modrm->got)
- return;
+ return 0;
+
if (!insn->opcode.got)
- insn_get_opcode(insn);
+ if (insn_get_opcode(insn))
+ return 1;
if (inat_has_modrm(insn->attr)) {
mod = get_next(insn_byte_t, insn);
@@ -302,17 +333,22 @@ void insn_get_modrm(struct insn *insn)
pfx_id = insn_last_prefix_id(insn);
insn->attr = inat_get_group_attribute(mod, pfx_id,
insn->attr);
- if (insn_is_avx(insn) && !inat_accept_vex(insn->attr))
- insn->attr = 0; /* This is bad */
+ if (insn_is_avx(insn) && !inat_accept_vex(insn->attr)) {
+ /* Bad insn */
+ insn->attr = 0;
+ return 1;
+ }
}
}
if (insn->x86_64 && inat_is_force64(insn->attr))
insn->opnd_bytes = 8;
+
modrm->got = 1;
+ return 0;
err_out:
- return;
+ return 1;
}
@@ -329,8 +365,11 @@ int insn_rip_relative(struct insn *insn)
if (!insn->x86_64)
return 0;
- if (!modrm->got)
- insn_get_modrm(insn);
+
+ if (!modrm->got) {
+ if (insn_get_modrm(insn))
+ return 0;
+ }
/*
* For rip-relative instructions, the mod field (top 2 bits)
* is zero and the r/m field (bottom 3 bits) is 0x5.
@@ -344,15 +383,23 @@ int insn_rip_relative(struct insn *insn)
*
* If necessary, first collects the instruction up to and including the
* ModRM byte.
+ *
+ * Returns:
+ * 0: if decoding succeeded
+ * !0: otherwise.
*/
-void insn_get_sib(struct insn *insn)
+int insn_get_sib(struct insn *insn)
{
insn_byte_t modrm;
if (insn->sib.got)
- return;
- if (!insn->modrm.got)
- insn_get_modrm(insn);
+ return 0;
+
+ if (!insn->modrm.got) {
+ if (insn_get_modrm(insn))
+ return 1;
+ }
+
if (insn->modrm.nbytes) {
modrm = (insn_byte_t)insn->modrm.value;
if (insn->addr_bytes != 2 &&
@@ -363,8 +410,10 @@ void insn_get_sib(struct insn *insn)
}
insn->sib.got = 1;
+ return 0;
+
err_out:
- return;
+ return 1;
}
@@ -375,15 +424,23 @@ void insn_get_sib(struct insn *insn)
* If necessary, first collects the instruction up to and including the
* SIB byte.
* Displacement value is sign-expanded.
+ *
+ * * Returns:
+ * 0: if decoding succeeded
+ * !0: otherwise.
*/
-void insn_get_displacement(struct insn *insn)
+int insn_get_displacement(struct insn *insn)
{
insn_byte_t mod, rm, base;
if (insn->displacement.got)
- return;
- if (!insn->sib.got)
- insn_get_sib(insn);
+ return 0;
+
+ if (!insn->sib.got) {
+ if (insn_get_sib(insn))
+ return 1;
+ }
+
if (insn->modrm.nbytes) {
/*
* Interpreting the modrm byte:
@@ -426,9 +483,10 @@ void insn_get_displacement(struct insn *insn)
}
out:
insn->displacement.got = 1;
+ return 0;
err_out:
- return;
+ return 1;
}
/* Decode moffset16/32/64. Return 0 if failed */
@@ -539,20 +597,27 @@ static int __get_immptr(struct insn *insn)
}
/**
- * insn_get_immediate() - Get the immediates of instruction
+ * insn_get_immediate() - Get the immediate in an instruction
* @insn: &struct insn containing instruction
*
* If necessary, first collects the instruction up to and including the
* displacement bytes.
* Basically, most of immediates are sign-expanded. Unsigned-value can be
- * get by bit masking with ((1 << (nbytes * 8)) - 1)
+ * computed by bit masking with ((1 << (nbytes * 8)) - 1)
+ *
+ * Returns:
+ * 0: on success
+ * !0: on error
*/
-void insn_get_immediate(struct insn *insn)
+int insn_get_immediate(struct insn *insn)
{
if (insn->immediate.got)
- return;
- if (!insn->displacement.got)
- insn_get_displacement(insn);
+ return 0;
+
+ if (!insn->displacement.got) {
+ if (insn_get_displacement(insn))
+ return 1;
+ }
if (inat_has_moffset(insn->attr)) {
if (!__get_moffset(insn))
@@ -605,9 +670,10 @@ void insn_get_immediate(struct insn *insn)
}
done:
insn->immediate.got = 1;
+ return 0;
err_out:
- return;
+ return 1;
}
/**
@@ -616,13 +682,49 @@ void insn_get_immediate(struct insn *insn)
*
* If necessary, first collects the instruction up to and including the
* immediates bytes.
- */
-void insn_get_length(struct insn *insn)
+ *
+ * Returns:
+ * - 0 on success
+ * - !0 on error
+*/
+int insn_get_length(struct insn *insn)
{
if (insn->length)
- return;
+ return 0;
+
if (!insn->immediate.got)
- insn_get_immediate(insn);
+ if (insn_get_immediate(insn))
+ return 1;
+
insn->length = (unsigned char)((unsigned long)insn->next_byte
- (unsigned long)insn->kaddr);
+
+ return 0;
+}
+
+/**
+ * insn_decode() - Decode an x86 instruction
+ * @insn: &struct insn to be initialized
+ * @kaddr: address (in kernel memory) of instruction (or copy thereof)
+ * @buf_len: length of the insn buffer at @kaddr
+ * @m: insn mode, see enum insn_mode
+ *
+ * Returns:
+ * 0: if decoding succeeded
+ * < 0: otherwise.
+ */
+int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m)
+{
+ if (m == INSN_MODE_KERN)
+ insn_init(insn, kaddr, buf_len, IS_ENABLED(CONFIG_X86_64));
+ else
+ insn_init(insn, kaddr, buf_len, m == INSN_MODE_64);
+
+ if (insn_get_length(insn))
+ return -EINVAL;
+
+ if (insn_complete(insn))
+ return 0;
+
+ return -EINVAL;
}
diff --git a/tools/arch/x86/include/asm/insn.h b/tools/arch/x86/include/asm/insn.h
index 568854b14d0a..f223bd7ec27e 100644
--- a/tools/arch/x86/include/asm/insn.h
+++ b/tools/arch/x86/include/asm/insn.h
@@ -87,13 +87,23 @@ struct insn {
#define X86_VEX_M_MAX 0x1f /* VEX3.M Maximum value */
extern void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64);
-extern void insn_get_prefixes(struct insn *insn);
-extern void insn_get_opcode(struct insn *insn);
-extern void insn_get_modrm(struct insn *insn);
-extern void insn_get_sib(struct insn *insn);
-extern void insn_get_displacement(struct insn *insn);
-extern void insn_get_immediate(struct insn *insn);
-extern void insn_get_length(struct insn *insn);
+extern int insn_get_prefixes(struct insn *insn);
+extern int insn_get_opcode(struct insn *insn);
+extern int insn_get_modrm(struct insn *insn);
+extern int insn_get_sib(struct insn *insn);
+extern int insn_get_displacement(struct insn *insn);
+extern int insn_get_immediate(struct insn *insn);
+extern int insn_get_length(struct insn *insn);
+
+enum insn_mode {
+ INSN_MODE_32,
+ INSN_MODE_64,
+ /* Mode is determined by the current kernel build. */
+ INSN_MODE_KERN,
+ INSN_NUM_MODES,
+};
+
+extern int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m);
/* Attribute will be determined after getting ModRM (for opcode groups) */
static inline void insn_get_attribute(struct insn *insn)
diff --git a/tools/arch/x86/lib/insn.c b/tools/arch/x86/lib/insn.c
index f3277d6e4ef2..41d2418302d9 100644
--- a/tools/arch/x86/lib/insn.c
+++ b/tools/arch/x86/lib/insn.c
@@ -13,6 +13,9 @@
#include "../include/asm/inat.h"
#include "../include/asm/insn.h"
+#include <linux/errno.h>
+#include <linux/kconfig.h>
+
#include "../include/asm/emulate_prefix.h"
/* Verify next sizeof(t) bytes can be on the same instruction */
@@ -98,8 +101,12 @@ static void insn_get_emulate_prefix(struct insn *insn)
* Populates the @insn->prefixes bitmap, and updates @insn->next_byte
* to point to the (first) opcode. No effect if @insn->prefixes.got
* is already set.
+ *
+ * * Returns:
+ * 0: on success
+ * !0: on error
*/
-void insn_get_prefixes(struct insn *insn)
+int insn_get_prefixes(struct insn *insn)
{
struct insn_field *prefixes = &insn->prefixes;
insn_attr_t attr;
@@ -107,7 +114,7 @@ void insn_get_prefixes(struct insn *insn)
int i, nb;
if (prefixes->got)
- return;
+ return 0;
insn_get_emulate_prefix(insn);
@@ -218,8 +225,10 @@ void insn_get_prefixes(struct insn *insn)
prefixes->got = 1;
+ return 0;
+
err_out:
- return;
+ return 1;
}
/**
@@ -231,14 +240,20 @@ void insn_get_prefixes(struct insn *insn)
* If necessary, first collects any preceding (prefix) bytes.
* Sets @insn->opcode.value = opcode1. No effect if @insn->opcode.got
* is already 1.
+ *
+ * Returns:
+ * 0: on success
+ * !0: on error
*/
-void insn_get_opcode(struct insn *insn)
+int insn_get_opcode(struct insn *insn)
{
struct insn_field *opcode = &insn->opcode;
insn_byte_t op;
int pfx_id;
+
if (opcode->got)
- return;
+ return 0;
+
if (!insn->prefixes.got)
insn_get_prefixes(insn);
@@ -255,9 +270,13 @@ void insn_get_opcode(struct insn *insn)
insn->attr = inat_get_avx_attribute(op, m, p);
if ((inat_must_evex(insn->attr) && !insn_is_evex(insn)) ||
(!inat_accept_vex(insn->attr) &&
- !inat_is_group(insn->attr)))
- insn->attr = 0; /* This instruction is bad */
- goto end; /* VEX has only 1 byte for opcode */
+ !inat_is_group(insn->attr))) {
+ /* This instruction is bad */
+ insn->attr = 0;
+ return 1;
+ }
+ /* VEX has only 1 byte for opcode */
+ goto end;
}
insn->attr = inat_get_opcode_attribute(op);
@@ -268,13 +287,18 @@ void insn_get_opcode(struct insn *insn)
pfx_id = insn_last_prefix_id(insn);
insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
}
- if (inat_must_vex(insn->attr))
- insn->attr = 0; /* This instruction is bad */
+
+ if (inat_must_vex(insn->attr)) {
+ /* This instruction is bad */
+ insn->attr = 0;
+ return 1;
+ }
end:
opcode->got = 1;
+ return 0;
err_out:
- return;
+ return 1;
}
/**
@@ -284,15 +308,22 @@ void insn_get_opcode(struct insn *insn)
* Populates @insn->modrm and updates @insn->next_byte to point past the
* ModRM byte, if any. If necessary, first collects the preceding bytes
* (prefixes and opcode(s)). No effect if @insn->modrm.got is already 1.
+ *
+ * Returns:
+ * 0: on success
+ * !0: on error
*/
-void insn_get_modrm(struct insn *insn)
+int insn_get_modrm(struct insn *insn)
{
struct insn_field *modrm = &insn->modrm;
insn_byte_t pfx_id, mod;
+
if (modrm->got)
- return;
+ return 0;
+
if (!insn->opcode.got)
- insn_get_opcode(insn);
+ if (insn_get_opcode(insn))
+ return 1;
if (inat_has_modrm(insn->attr)) {
mod = get_next(insn_byte_t, insn);
@@ -302,17 +333,22 @@ void insn_get_modrm(struct insn *insn)
pfx_id = insn_last_prefix_id(insn);
insn->attr = inat_get_group_attribute(mod, pfx_id,
insn->attr);
- if (insn_is_avx(insn) && !inat_accept_vex(insn->attr))
- insn->attr = 0; /* This is bad */
+ if (insn_is_avx(insn) && !inat_accept_vex(insn->attr)) {
+ /* Bad insn */
+ insn->attr = 0;
+ return 1;
+ }
}
}
if (insn->x86_64 && inat_is_force64(insn->attr))
insn->opnd_bytes = 8;
+
modrm->got = 1;
+ return 0;
err_out:
- return;
+ return 1;
}
@@ -329,8 +365,11 @@ int insn_rip_relative(struct insn *insn)
if (!insn->x86_64)
return 0;
- if (!modrm->got)
- insn_get_modrm(insn);
+
+ if (!modrm->got) {
+ if (insn_get_modrm(insn))
+ return 0;
+ }
/*
* For rip-relative instructions, the mod field (top 2 bits)
* is zero and the r/m field (bottom 3 bits) is 0x5.
@@ -344,15 +383,23 @@ int insn_rip_relative(struct insn *insn)
*
* If necessary, first collects the instruction up to and including the
* ModRM byte.
+ *
+ * Returns:
+ * 0: if decoding succeeded
+ * !0: otherwise.
*/
-void insn_get_sib(struct insn *insn)
+int insn_get_sib(struct insn *insn)
{
insn_byte_t modrm;
if (insn->sib.got)
- return;
- if (!insn->modrm.got)
- insn_get_modrm(insn);
+ return 0;
+
+ if (!insn->modrm.got) {
+ if (insn_get_modrm(insn))
+ return 1;
+ }
+
if (insn->modrm.nbytes) {
modrm = (insn_byte_t)insn->modrm.value;
if (insn->addr_bytes != 2 &&
@@ -363,8 +410,10 @@ void insn_get_sib(struct insn *insn)
}
insn->sib.got = 1;
+ return 0;
+
err_out:
- return;
+ return 1;
}
@@ -375,15 +424,23 @@ void insn_get_sib(struct insn *insn)
* If necessary, first collects the instruction up to and including the
* SIB byte.
* Displacement value is sign-expanded.
+ *
+ * * Returns:
+ * 0: if decoding succeeded
+ * !0: otherwise.
*/
-void insn_get_displacement(struct insn *insn)
+int insn_get_displacement(struct insn *insn)
{
insn_byte_t mod, rm, base;
if (insn->displacement.got)
- return;
- if (!insn->sib.got)
- insn_get_sib(insn);
+ return 0;
+
+ if (!insn->sib.got) {
+ if (insn_get_sib(insn))
+ return 1;
+ }
+
if (insn->modrm.nbytes) {
/*
* Interpreting the modrm byte:
@@ -426,9 +483,10 @@ void insn_get_displacement(struct insn *insn)
}
out:
insn->displacement.got = 1;
+ return 0;
err_out:
- return;
+ return 1;
}
/* Decode moffset16/32/64. Return 0 if failed */
@@ -539,20 +597,27 @@ static int __get_immptr(struct insn *insn)
}
/**
- * insn_get_immediate() - Get the immediates of instruction
+ * insn_get_immediate() - Get the immediate in an instruction
* @insn: &struct insn containing instruction
*
* If necessary, first collects the instruction up to and including the
* displacement bytes.
* Basically, most of immediates are sign-expanded. Unsigned-value can be
- * get by bit masking with ((1 << (nbytes * 8)) - 1)
+ * computed by bit masking with ((1 << (nbytes * 8)) - 1)
+ *
+ * Returns:
+ * 0: on success
+ * !0: on error
*/
-void insn_get_immediate(struct insn *insn)
+int insn_get_immediate(struct insn *insn)
{
if (insn->immediate.got)
- return;
- if (!insn->displacement.got)
- insn_get_displacement(insn);
+ return 0;
+
+ if (!insn->displacement.got) {
+ if (insn_get_displacement(insn))
+ return 1;
+ }
if (inat_has_moffset(insn->attr)) {
if (!__get_moffset(insn))
@@ -605,9 +670,10 @@ void insn_get_immediate(struct insn *insn)
}
done:
insn->immediate.got = 1;
+ return 0;
err_out:
- return;
+ return 1;
}
/**
@@ -616,13 +682,49 @@ void insn_get_immediate(struct insn *insn)
*
* If necessary, first collects the instruction up to and including the
* immediates bytes.
- */
-void insn_get_length(struct insn *insn)
+ *
+ * Returns:
+ * - 0 on success
+ * - !0 on error
+*/
+int insn_get_length(struct insn *insn)
{
if (insn->length)
- return;
+ return 0;
+
if (!insn->immediate.got)
- insn_get_immediate(insn);
+ if (insn_get_immediate(insn))
+ return 1;
+
insn->length = (unsigned char)((unsigned long)insn->next_byte
- (unsigned long)insn->kaddr);
+
+ return 0;
+}
+
+/**
+ * insn_decode() - Decode an x86 instruction
+ * @insn: &struct insn to be initialized
+ * @kaddr: address (in kernel memory) of instruction (or copy thereof)
+ * @buf_len: length of the insn buffer at @kaddr
+ * @m: insn mode, see enum insn_mode
+ *
+ * Returns:
+ * 0: if decoding succeeded
+ * < 0: otherwise.
+ */
+int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m)
+{
+ if (m == INSN_MODE_KERN)
+ insn_init(insn, kaddr, buf_len, IS_ENABLED(CONFIG_X86_64));
+ else
+ insn_init(insn, kaddr, buf_len, m == INSN_MODE_64);
+
+ if (insn_get_length(insn))
+ return -EINVAL;
+
+ if (insn_complete(insn))
+ return 0;
+
+ return -EINVAL;
}
diff --git a/tools/include/linux/kconfig.h b/tools/include/linux/kconfig.h
new file mode 100644
index 000000000000..1555a0c4f345
--- /dev/null
+++ b/tools/include/linux/kconfig.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TOOLS_LINUX_KCONFIG_H
+#define _TOOLS_LINUX_KCONFIG_H
+
+/* CONFIG_CC_VERSION_TEXT (Do not delete this comment. See help in Kconfig) */
+
+#ifdef CONFIG_CPU_BIG_ENDIAN
+#define __BIG_ENDIAN 4321
+#else
+#define __LITTLE_ENDIAN 1234
+#endif
+
+#define __ARG_PLACEHOLDER_1 0,
+#define __take_second_arg(__ignored, val, ...) val
+
+/*
+ * The use of "&&" / "||" is limited in certain expressions.
+ * The following enable to calculate "and" / "or" with macro expansion only.
+ */
+#define __and(x, y) ___and(x, y)
+#define ___and(x, y) ____and(__ARG_PLACEHOLDER_##x, y)
+#define ____and(arg1_or_junk, y) __take_second_arg(arg1_or_junk y, 0)
+
+#define __or(x, y) ___or(x, y)
+#define ___or(x, y) ____or(__ARG_PLACEHOLDER_##x, y)
+#define ____or(arg1_or_junk, y) __take_second_arg(arg1_or_junk 1, y)
+
+/*
+ * Helper macros to use CONFIG_ options in C/CPP expressions. Note that
+ * these only work with boolean and tristate options.
+ */
+
+/*
+ * Getting something that works in C and CPP for an arg that may or may
+ * not be defined is tricky. Here, if we have "#define CONFIG_BOOGER 1"
+ * we match on the placeholder define, insert the "0," for arg1 and generate
+ * the triplet (0, 1, 0). Then the last step cherry picks the 2nd arg (a one).
+ * When CONFIG_BOOGER is not defined, we generate a (... 1, 0) pair, and when
+ * the last step cherry picks the 2nd arg, we get a zero.
+ */
+#define __is_defined(x) ___is_defined(x)
+#define ___is_defined(val) ____is_defined(__ARG_PLACEHOLDER_##val)
+#define ____is_defined(arg1_or_junk) __take_second_arg(arg1_or_junk 1, 0)
+
+/*
+ * IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0
+ * otherwise. For boolean options, this is equivalent to
+ * IS_ENABLED(CONFIG_FOO).
+ */
+#define IS_BUILTIN(option) __is_defined(option)
+
+/*
+ * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0
+ * otherwise.
+ */
+#define IS_MODULE(option) __is_defined(option##_MODULE)
+
+/*
+ * IS_REACHABLE(CONFIG_FOO) evaluates to 1 if the currently compiled
+ * code can call a function defined in code compiled based on CONFIG_FOO.
+ * This is similar to IS_ENABLED(), but returns false when invoked from
+ * built-in code when CONFIG_FOO is set to 'm'.
+ */
+#define IS_REACHABLE(option) __or(IS_BUILTIN(option), \
+ __and(IS_MODULE(option), __is_defined(MODULE)))
+
+/*
+ * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm',
+ * 0 otherwise.
+ */
+#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
+
+#endif /* _TOOLS_LINUX_KCONFIG_H */
--
2.21.0