x86/insn: Support big endian cross-compiles

The x86 instruction decoder code is shared across the kernel source and the tools. Currently objtool seems to be the only tool from build tools needed which breaks x86 cross-compilation on big endian systems. Make the x86 instruction decoder build host endianness agnostic to support x86 cross-compilation and enable objtool to implement endianness awareness for big endian architectures support. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Co-developed-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
mariux64 · Jan 14, 2021 · 1d509f2 · 1d509f2
1 parent c8d7b7e
commit 1d509f2
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Showing 5 changed files with 160 additions and 112 deletions.
diff --git a/arch/x86/include/asm/insn.h b/arch/x86/include/asm/insn.h
@@ -7,9 +7,12 @@
  * Copyright (C) IBM Corporation, 2009
  */
 
+#include <asm/byteorder.h>
 /* insn_attr_t is defined in inat.h */
 #include <asm/inat.h>
 
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
+
 struct insn_field {
 	union {
 		insn_value_t value;
@@ -20,6 +23,36 @@ struct insn_field {
 	unsigned char nbytes;
 };
 
+static inline void insn_field_set(struct insn_field *p, insn_value_t v,
+				  unsigned char n)
+{
+	p->value = v;
+	p->nbytes = n;
+}
+
+#else
+
+struct insn_field {
+	insn_value_t value;
+	union {
+		insn_value_t little;
+		insn_byte_t bytes[4];
+	};
+	/* !0 if we've run insn_get_xxx() for this field */
+	unsigned char got;
+	unsigned char nbytes;
+};
+
+static inline void insn_field_set(struct insn_field *p, insn_value_t v,
+				  unsigned char n)
+{
+	p->value = v;
+	p->little = __cpu_to_le32(v);
+	p->nbytes = n;
+}
+
+#endif
+
 struct insn {
 	struct insn_field prefixes;	/*
 					 * Prefixes

diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
@@ -5,6 +5,7 @@
  * Copyright (C) IBM Corporation, 2002, 2004, 2009
  */
 
+#include <linux/kernel.h>
 #ifdef __KERNEL__
 #include <linux/string.h>
 #else
@@ -15,15 +16,28 @@
 
 #include <asm/emulate_prefix.h>
 
+#define leXX_to_cpu(t, r)						\
+({									\
+	__typeof__(t) v;						\
+	switch (sizeof(t)) {						\
+	case 4: v = le32_to_cpu(r); break;				\
+	case 2: v = le16_to_cpu(r); break;				\
+	case 1:	v = r; break;						\
+	default:							\
+		BUILD_BUG(); break;					\
+	}								\
+	v;								\
+})
+
 /* Verify next sizeof(t) bytes can be on the same instruction */
 #define validate_next(t, insn, n)	\
 	((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
 
 #define __get_next(t, insn)	\
-	({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); r; })
+	({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
 
 #define __peek_nbyte_next(t, insn, n)	\
-	({ t r = *(t*)((insn)->next_byte + n); r; })
+	({ t r = *(t*)((insn)->next_byte + n); leXX_to_cpu(t, r); })
 
 #define get_next(t, insn)	\
 	({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })
@@ -157,8 +171,7 @@ void insn_get_prefixes(struct insn *insn)
 		b = peek_next(insn_byte_t, insn);
 		attr = inat_get_opcode_attribute(b);
 		if (inat_is_rex_prefix(attr)) {
-			insn->rex_prefix.value = b;
-			insn->rex_prefix.nbytes = 1;
+			insn_field_set(&insn->rex_prefix, b, 1);
 			insn->next_byte++;
 			if (X86_REX_W(b))
 				/* REX.W overrides opnd_size */
@@ -295,8 +308,7 @@ void insn_get_modrm(struct insn *insn)
 
 	if (inat_has_modrm(insn->attr)) {
 		mod = get_next(insn_byte_t, insn);
-		modrm->value = mod;
-		modrm->nbytes = 1;
+		insn_field_set(modrm, mod, 1);
 		if (inat_is_group(insn->attr)) {
 			pfx_id = insn_last_prefix_id(insn);
 			insn->attr = inat_get_group_attribute(mod, pfx_id,
@@ -334,7 +346,7 @@ int insn_rip_relative(struct insn *insn)
 	 * For rip-relative instructions, the mod field (top 2 bits)
 	 * is zero and the r/m field (bottom 3 bits) is 0x5.
 	 */
-	return (modrm->nbytes && (modrm->value & 0xc7) == 0x5);
+	return (modrm->nbytes && (modrm->bytes[0] & 0xc7) == 0x5);
 }
 
 /**
@@ -353,11 +365,11 @@ void insn_get_sib(struct insn *insn)
 	if (!insn->modrm.got)
 		insn_get_modrm(insn);
 	if (insn->modrm.nbytes) {
-		modrm = (insn_byte_t)insn->modrm.value;
+		modrm = insn->modrm.bytes[0];
 		if (insn->addr_bytes != 2 &&
 		    X86_MODRM_MOD(modrm) != 3 && X86_MODRM_RM(modrm) == 4) {
-			insn->sib.value = get_next(insn_byte_t, insn);
-			insn->sib.nbytes = 1;
+			insn_field_set(&insn->sib,
+				       get_next(insn_byte_t, insn), 1);
 		}
 	}
 	insn->sib.got = 1;
@@ -407,19 +419,18 @@ void insn_get_displacement(struct insn *insn)
 		if (mod == 3)
 			goto out;
 		if (mod == 1) {
-			insn->displacement.value = get_next(signed char, insn);
-			insn->displacement.nbytes = 1;
+			insn_field_set(&insn->displacement,
+				       get_next(signed char, insn), 1);
 		} else if (insn->addr_bytes == 2) {
 			if ((mod == 0 && rm == 6) || mod == 2) {
-				insn->displacement.value =
-					 get_next(short, insn);
-				insn->displacement.nbytes = 2;
+				insn_field_set(&insn->displacement,
+					       get_next(short, insn), 2);
 			}
 		} else {
 			if ((mod == 0 && rm == 5) || mod == 2 ||
 			    (mod == 0 && base == 5)) {
-				insn->displacement.value = get_next(int, insn);
-				insn->displacement.nbytes = 4;
+				insn_field_set(&insn->displacement,
+					       get_next(int, insn), 4);
 			}
 		}
 	}
@@ -435,18 +446,14 @@ static int __get_moffset(struct insn *insn)
 {
 	switch (insn->addr_bytes) {
 	case 2:
-		insn->moffset1.value = get_next(short, insn);
-		insn->moffset1.nbytes = 2;
+		insn_field_set(&insn->moffset1, get_next(short, insn), 2);
 		break;
 	case 4:
-		insn->moffset1.value = get_next(int, insn);
-		insn->moffset1.nbytes = 4;
+		insn_field_set(&insn->moffset1, get_next(int, insn), 4);
 		break;
 	case 8:
-		insn->moffset1.value = get_next(int, insn);
-		insn->moffset1.nbytes = 4;
-		insn->moffset2.value = get_next(int, insn);
-		insn->moffset2.nbytes = 4;
+		insn_field_set(&insn->moffset1, get_next(int, insn), 4);
+		insn_field_set(&insn->moffset2, get_next(int, insn), 4);
 		break;
 	default:	/* opnd_bytes must be modified manually */
 		goto err_out;
@@ -464,13 +471,11 @@ static int __get_immv32(struct insn *insn)
 {
 	switch (insn->opnd_bytes) {
 	case 2:
-		insn->immediate.value = get_next(short, insn);
-		insn->immediate.nbytes = 2;
+		insn_field_set(&insn->immediate, get_next(short, insn), 2);
 		break;
 	case 4:
 	case 8:
-		insn->immediate.value = get_next(int, insn);
-		insn->immediate.nbytes = 4;
+		insn_field_set(&insn->immediate, get_next(int, insn), 4);
 		break;
 	default:	/* opnd_bytes must be modified manually */
 		goto err_out;
@@ -487,18 +492,15 @@ static int __get_immv(struct insn *insn)
 {
 	switch (insn->opnd_bytes) {
 	case 2:
-		insn->immediate1.value = get_next(short, insn);
-		insn->immediate1.nbytes = 2;
+		insn_field_set(&insn->immediate1, get_next(short, insn), 2);
 		break;
 	case 4:
-		insn->immediate1.value = get_next(int, insn);
+		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
 		insn->immediate1.nbytes = 4;
 		break;
 	case 8:
-		insn->immediate1.value = get_next(int, insn);
-		insn->immediate1.nbytes = 4;
-		insn->immediate2.value = get_next(int, insn);
-		insn->immediate2.nbytes = 4;
+		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
+		insn_field_set(&insn->immediate2, get_next(int, insn), 4);
 		break;
 	default:	/* opnd_bytes must be modified manually */
 		goto err_out;
@@ -515,21 +517,18 @@ static int __get_immptr(struct insn *insn)
 {
 	switch (insn->opnd_bytes) {
 	case 2:
-		insn->immediate1.value = get_next(short, insn);
-		insn->immediate1.nbytes = 2;
+		insn_field_set(&insn->immediate1, get_next(short, insn), 2);
 		break;
 	case 4:
-		insn->immediate1.value = get_next(int, insn);
-		insn->immediate1.nbytes = 4;
+		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
 		break;
 	case 8:
 		/* ptr16:64 is not exist (no segment) */
 		return 0;
 	default:	/* opnd_bytes must be modified manually */
 		goto err_out;
 	}
-	insn->immediate2.value = get_next(unsigned short, insn);
-	insn->immediate2.nbytes = 2;
+	insn_field_set(&insn->immediate2, get_next(unsigned short, insn), 2);
 	insn->immediate1.got = insn->immediate2.got = 1;
 
 	return 1;
@@ -565,22 +564,17 @@ void insn_get_immediate(struct insn *insn)
 
 	switch (inat_immediate_size(insn->attr)) {
 	case INAT_IMM_BYTE:
-		insn->immediate.value = get_next(signed char, insn);
-		insn->immediate.nbytes = 1;
+		insn_field_set(&insn->immediate, get_next(signed char, insn), 1);
 		break;
 	case INAT_IMM_WORD:
-		insn->immediate.value = get_next(short, insn);
-		insn->immediate.nbytes = 2;
+		insn_field_set(&insn->immediate, get_next(short, insn), 2);
 		break;
 	case INAT_IMM_DWORD:
-		insn->immediate.value = get_next(int, insn);
-		insn->immediate.nbytes = 4;
+		insn_field_set(&insn->immediate, get_next(int, insn), 4);
 		break;
 	case INAT_IMM_QWORD:
-		insn->immediate1.value = get_next(int, insn);
-		insn->immediate1.nbytes = 4;
-		insn->immediate2.value = get_next(int, insn);
-		insn->immediate2.nbytes = 4;
+		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
+		insn_field_set(&insn->immediate2, get_next(int, insn), 4);
 		break;
 	case INAT_IMM_PTR:
 		if (!__get_immptr(insn))
@@ -599,8 +593,7 @@ void insn_get_immediate(struct insn *insn)
 		goto err_out;
 	}
 	if (inat_has_second_immediate(insn->attr)) {
-		insn->immediate2.value = get_next(signed char, insn);
-		insn->immediate2.nbytes = 1;
+		insn_field_set(&insn->immediate2, get_next(signed char, insn), 1);
 	}
 done:
 	insn->immediate.got = 1;

diff --git a/arch/x86/tools/insn_sanity.c b/arch/x86/tools/insn_sanity.c
@@ -14,10 +14,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
-
-#define unlikely(cond) (cond)
-#define ARRAY_SIZE(a)	(sizeof(a)/sizeof(a[0]))
-
 #include <asm/insn.h>
 #include <inat.c>
 #include <insn.c>

diff --git a/tools/arch/x86/include/asm/insn.h b/tools/arch/x86/include/asm/insn.h
@@ -7,9 +7,12 @@
  * Copyright (C) IBM Corporation, 2009
  */
 
+#include <asm/byteorder.h>
 /* insn_attr_t is defined in inat.h */
 #include "inat.h"
 
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
+
 struct insn_field {
 	union {
 		insn_value_t value;
@@ -20,6 +23,36 @@ struct insn_field {
 	unsigned char nbytes;
 };
 
+static inline void insn_field_set(struct insn_field *p, insn_value_t v,
+				  unsigned char n)
+{
+	p->value = v;
+	p->nbytes = n;
+}
+
+#else
+
+struct insn_field {
+	insn_value_t value;
+	union {
+		insn_value_t little;
+		insn_byte_t bytes[4];
+	};
+	/* !0 if we've run insn_get_xxx() for this field */
+	unsigned char got;
+	unsigned char nbytes;
+};
+
+static inline void insn_field_set(struct insn_field *p, insn_value_t v,
+				  unsigned char n)
+{
+	p->value = v;
+	p->little = __cpu_to_le32(v);
+	p->nbytes = n;
+}
+
+#endif
+
 struct insn {
 	struct insn_field prefixes;	/*
 					 * Prefixes