Commit 8bfe2732 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Josh Poimboeuf
Browse files

objtool: Fix x86 orc generation on big endian cross-compiles 



Correct objtool orc generation endianness problems to enable fully
functional x86 cross-compiles on big endian hardware.

Introduce bswap_if_needed() macro, which does a byte swap if target
endianness doesn't match the host, i.e. cross-compilation for little
endian on big endian and vice versa.  The macro is used for conversion
of multi-byte values which are read from / about to be written to a
target native endianness ELF file.

Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
parent a1a664ec

arch/x86/include/asm/orc_types.h

+10 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ 
#define ORC_REG_MAX			15



#ifndef __ASSEMBLY__

#include <asm/byteorder.h>



/*

 * This struct is more or less a vastly simplified version of the DWARF Call

 * Frame Information standard.  It contains only the necessary parts of DWARF
@@ -51,10 +53,18 @@ 
struct orc_entry {

	s16		sp_offset;

	s16		bp_offset;

#if defined(__LITTLE_ENDIAN_BITFIELD)

	unsigned	sp_reg:4;

	unsigned	bp_reg:4;

	unsigned	type:2;

	unsigned	end:1;

#elif defined(__BIG_ENDIAN_BITFIELD)

	unsigned	bp_reg:4;

	unsigned	sp_reg:4;

	unsigned	unused:5;

	unsigned	end:1;

	unsigned	type:2;

#endif

} __packed;



#endif /* __ASSEMBLY__ */

tools/arch/x86/include/asm/orc_types.h

+10 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ 
#define ORC_REG_MAX			15



#ifndef __ASSEMBLY__

#include <asm/byteorder.h>



/*

 * This struct is more or less a vastly simplified version of the DWARF Call

 * Frame Information standard.  It contains only the necessary parts of DWARF
@@ -51,10 +53,18 @@ 
struct orc_entry {

	s16		sp_offset;

	s16		bp_offset;

#if defined(__LITTLE_ENDIAN_BITFIELD)

	unsigned	sp_reg:4;

	unsigned	bp_reg:4;

	unsigned	type:2;

	unsigned	end:1;

#elif defined(__BIG_ENDIAN_BITFIELD)

	unsigned	bp_reg:4;

	unsigned	sp_reg:4;

	unsigned	unused:5;

	unsigned	end:1;

	unsigned	type:2;

#endif

} __packed;



#endif /* __ASSEMBLY__ */

tools/objtool/arch/x86/include/arch_endianness.h

0 → 100644
+9 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-or-later */

#ifndef _ARCH_ENDIANNESS_H

#define _ARCH_ENDIANNESS_H



#include <endian.h>



#define __TARGET_BYTE_ORDER __LITTLE_ENDIAN



#endif /* _ARCH_ENDIANNESS_H */

tools/objtool/check.c

+3 −2
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include "special.h"

#include "warn.h"

#include "arch_elf.h"

#include "endianness.h"



#include <linux/objtool.h>

#include <linux/hashtable.h>
@@ -1435,7 +1436,7 @@ static int read_unwind_hints(struct objtool_file *file) 
		cfa = &insn->cfi.cfa;



		if (hint->type == UNWIND_HINT_TYPE_RET_OFFSET) {

			insn->ret_offset = hint->sp_offset;

			insn->ret_offset = bswap_if_needed(hint->sp_offset);

			continue;

		}
@@ -1447,7 +1448,7 @@ static int read_unwind_hints(struct objtool_file *file) 
			return -1;

		}



		cfa->offset = hint->sp_offset;

		cfa->offset = bswap_if_needed(hint->sp_offset);

		insn->cfi.type = hint->type;

		insn->cfi.end = hint->end;

	}

tools/objtool/endianness.h

0 → 100644
+38 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-or-later */

#ifndef _OBJTOOL_ENDIANNESS_H

#define _OBJTOOL_ENDIANNESS_H



#include <linux/kernel.h>

#include <endian.h>

#include "arch_endianness.h"



#ifndef __TARGET_BYTE_ORDER

#error undefined arch __TARGET_BYTE_ORDER

#endif



#if __BYTE_ORDER != __TARGET_BYTE_ORDER

#define __NEED_BSWAP 1

#else

#define __NEED_BSWAP 0

#endif



/*

 * Does a byte swap if target endianness doesn't match the host, i.e. cross

 * compilation for little endian on big endian and vice versa.

 * To be used for multi-byte values conversion, which are read from / about

 * to be written to a target native endianness ELF file.

 */

#define bswap_if_needed(val)						\

({									\

	__typeof__(val) __ret;						\

	switch (sizeof(val)) {						\

	case 8: __ret = __NEED_BSWAP ? bswap_64(val) : (val); break;	\

	case 4: __ret = __NEED_BSWAP ? bswap_32(val) : (val); break;	\

	case 2: __ret = __NEED_BSWAP ? bswap_16(val) : (val); break;	\

	default:							\

		BUILD_BUG(); break;					\

	}								\

	__ret;								\

})



#endif /* _OBJTOOL_ENDIANNESS_H */