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Date:   Sun, 28 Feb 2021 03:39:10 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Fangrui Song <maskray@...gle.com>,
        clang-built-linux@...glegroups.com,
        "H . J . Lu" <hjl.tools@...il.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Brian Gerst <brgerst@...il.com>,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Chao Yu <chao@...nel.org>,
        "Darrick J. Wong" <djwong@...nel.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        Ingo Molnar <mingo@...hat.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Jethro Beekman <jethro@...tanix.com>,
        Kees Cook <keescook@...omium.org>,
        Miklos Szeredi <miklos@...redi.hu>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Sasha Levin <sashal@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-xfs@...r.kernel.org
Subject: [PATCH RFC] x86: remove toolchain check for X32 ABI capability

This commit reverts 0bf6276392e9 ("x32: Warn and disable rather than
error if binutils too old").

The help text in arch/x86/Kconfig says enabling the X32 ABI support
needs binutils 2.22 or later. This is met because the minimal binutils
version is 2.23 according to Documentation/process/changes.rst.

I would not say I am not familiar with toolchain configuration, but
I checked the configure.tgt code in binutils. The elf32_x86_64
emulation mode seems to be included when it is configured for the
x86_64-*-linux-* target.

I also tried lld and llvm-objcopy, and succeeded in building x32 VDSO.

I removed the compile-time check in arch/x86/Makefile, in the hope of
elf32_x86_64 being always supported.

With this, CONFIG_X86_X32 and CONFIG_X86_X32_ABI will be equivalent.
Rename the former to the latter.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 arch/x86/Kconfig                       |  8 ++------
 arch/x86/Makefile                      | 16 ----------------
 arch/x86/include/asm/syscall_wrapper.h |  6 +++---
 arch/x86/include/asm/vdso.h            |  2 +-
 arch/x86/kernel/process_64.c           |  2 +-
 fs/fuse/file.c                         |  2 +-
 fs/xfs/xfs_ioctl32.c                   |  2 +-
 sound/core/control_compat.c            | 16 ++++++++--------
 sound/core/pcm_compat.c                | 20 ++++++++++----------
 9 files changed, 27 insertions(+), 47 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2792879d398e..7272cba2744c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2865,7 +2865,7 @@ config IA32_AOUT
 	help
 	  Support old a.out binaries in the 32bit emulation.
 
-config X86_X32
+config X86_X32_ABI
 	bool "x32 ABI for 64-bit mode"
 	depends on X86_64
 	help
@@ -2874,10 +2874,6 @@ config X86_X32
 	  full 64-bit register file and wide data path while leaving
 	  pointers at 32 bits for smaller memory footprint.
 
-	  You will need a recent binutils (2.22 or later) with
-	  elf32_x86_64 support enabled to compile a kernel with this
-	  option set.
-
 config COMPAT_32
 	def_bool y
 	depends on IA32_EMULATION || X86_32
@@ -2886,7 +2882,7 @@ config COMPAT_32
 
 config COMPAT
 	def_bool y
-	depends on IA32_EMULATION || X86_X32
+	depends on IA32_EMULATION || X86_X32_ABI
 
 if COMPAT
 config COMPAT_FOR_U64_ALIGNMENT
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 2d6d5a28c3bf..e163549f5be7 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -125,22 +125,6 @@ else
         KBUILD_CFLAGS += -mcmodel=kernel
 endif
 
-ifdef CONFIG_X86_X32
-	x32_ld_ok := $(call try-run,\
-			/bin/echo -e '1: .quad 1b' | \
-			$(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" - && \
-			$(OBJCOPY) -O elf32-x86-64 "$$TMP" "$$TMPO" && \
-			$(LD) -m elf32_x86_64 "$$TMPO" -o "$$TMP",y,n)
-        ifeq ($(x32_ld_ok),y)
-                CONFIG_X86_X32_ABI := y
-                KBUILD_AFLAGS += -DCONFIG_X86_X32_ABI
-                KBUILD_CFLAGS += -DCONFIG_X86_X32_ABI
-        else
-                $(warning CONFIG_X86_X32 enabled but no binutils support)
-        endif
-endif
-export CONFIG_X86_X32_ABI
-
 #
 # If the function graph tracer is used with mcount instead of fentry,
 # '-maccumulate-outgoing-args' is needed to prevent a GCC bug
diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h
index a84333adeef2..69bf87c41a0b 100644
--- a/arch/x86/include/asm/syscall_wrapper.h
+++ b/arch/x86/include/asm/syscall_wrapper.h
@@ -158,7 +158,7 @@ extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
 #endif /* CONFIG_IA32_EMULATION */
 
 
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 /*
  * For the x32 ABI, we need to create a stub for compat_sys_*() which is aware
  * of the x86-64-style parameter ordering of x32 syscalls. The syscalls common
@@ -176,12 +176,12 @@ extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
 
 #define __X32_COMPAT_SYS_NI(name)					\
 	__SYS_NI(x32, compat_sys_##name)
-#else /* CONFIG_X86_X32 */
+#else /* CONFIG_X86_X32_ABI */
 #define __X32_COMPAT_SYS_STUB0(name)
 #define __X32_COMPAT_SYS_STUBx(x, name, ...)
 #define __X32_COMPAT_COND_SYSCALL(name)
 #define __X32_COMPAT_SYS_NI(name)
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 
 
 #ifdef CONFIG_COMPAT
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 98aa103eb4ab..2963a2f5dbc4 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -37,7 +37,7 @@ struct vdso_image {
 extern const struct vdso_image vdso_image_64;
 #endif
 
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 extern const struct vdso_image vdso_image_x32;
 #endif
 
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index d08307df69ad..a93b6f4296fc 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -656,7 +656,7 @@ void set_personality_64bit(void)
 
 static void __set_personality_x32(void)
 {
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 	if (current->mm)
 		current->mm->context.flags = 0;
 
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 8cccecb55fb8..c53c620d1a7a 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2797,7 +2797,7 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
 #else
 	if (flags & FUSE_IOCTL_COMPAT) {
 		inarg.flags |= FUSE_IOCTL_32BIT;
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 		if (in_x32_syscall())
 			inarg.flags |= FUSE_IOCTL_COMPAT_X32;
 #endif
diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
index 33c09ec8e6c0..e8038bc966e7 100644
--- a/fs/xfs/xfs_ioctl32.c
+++ b/fs/xfs/xfs_ioctl32.c
@@ -233,7 +233,7 @@ xfs_compat_ioc_fsbulkstat(
 	inumbers_fmt_pf		inumbers_func = xfs_fsinumbers_fmt_compat;
 	bulkstat_one_fmt_pf	bs_one_func = xfs_fsbulkstat_one_fmt_compat;
 
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 	if (in_x32_syscall()) {
 		/*
 		 * ... but on x32 the input xfs_fsop_bulkreq has pointers
diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c
index 1d708aab9c98..5d1b94bda2cd 100644
--- a/sound/core/control_compat.c
+++ b/sound/core/control_compat.c
@@ -153,7 +153,7 @@ struct snd_ctl_elem_value32 {
         unsigned char reserved[128];
 };
 
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 /* x32 has a different alignment for 64bit values from ia32 */
 struct snd_ctl_elem_value_x32 {
 	struct snd_ctl_elem_id id;
@@ -165,7 +165,7 @@ struct snd_ctl_elem_value_x32 {
 	} value;
 	unsigned char reserved[128];
 };
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 
 /* get the value type and count of the control */
 static int get_ctl_type(struct snd_card *card, struct snd_ctl_elem_id *id,
@@ -350,7 +350,7 @@ static int snd_ctl_elem_write_user_compat(struct snd_ctl_file *file,
 	return ctl_elem_write_user(file, data32, &data32->value);
 }
 
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 static int snd_ctl_elem_read_user_x32(struct snd_card *card,
 				      struct snd_ctl_elem_value_x32 __user *data32)
 {
@@ -362,7 +362,7 @@ static int snd_ctl_elem_write_user_x32(struct snd_ctl_file *file,
 {
 	return ctl_elem_write_user(file, data32, &data32->value);
 }
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 
 /* add or replace a user control */
 static int snd_ctl_elem_add_compat(struct snd_ctl_file *file,
@@ -421,10 +421,10 @@ enum {
 	SNDRV_CTL_IOCTL_ELEM_WRITE32 = _IOWR('U', 0x13, struct snd_ctl_elem_value32),
 	SNDRV_CTL_IOCTL_ELEM_ADD32 = _IOWR('U', 0x17, struct snd_ctl_elem_info32),
 	SNDRV_CTL_IOCTL_ELEM_REPLACE32 = _IOWR('U', 0x18, struct snd_ctl_elem_info32),
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 	SNDRV_CTL_IOCTL_ELEM_READ_X32 = _IOWR('U', 0x12, struct snd_ctl_elem_value_x32),
 	SNDRV_CTL_IOCTL_ELEM_WRITE_X32 = _IOWR('U', 0x13, struct snd_ctl_elem_value_x32),
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 };
 
 static inline long snd_ctl_ioctl_compat(struct file *file, unsigned int cmd, unsigned long arg)
@@ -463,12 +463,12 @@ static inline long snd_ctl_ioctl_compat(struct file *file, unsigned int cmd, uns
 		return snd_ctl_elem_add_compat(ctl, argp, 0);
 	case SNDRV_CTL_IOCTL_ELEM_REPLACE32:
 		return snd_ctl_elem_add_compat(ctl, argp, 1);
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 	case SNDRV_CTL_IOCTL_ELEM_READ_X32:
 		return snd_ctl_elem_read_user_x32(ctl->card, argp);
 	case SNDRV_CTL_IOCTL_ELEM_WRITE_X32:
 		return snd_ctl_elem_write_user_x32(ctl, argp);
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 	}
 
 	down_read(&snd_ioctl_rwsem);
diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index 590a46a9e78d..937f5117a81f 100644
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -147,13 +147,13 @@ static int snd_pcm_ioctl_channel_info_compat(struct snd_pcm_substream *substream
 	return err;
 }
 
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 /* X32 ABI has the same struct as x86-64 for snd_pcm_channel_info */
 static int snd_pcm_channel_info_user(struct snd_pcm_substream *substream,
 				     struct snd_pcm_channel_info __user *src);
 #define snd_pcm_ioctl_channel_info_x32(s, p)	\
 	snd_pcm_channel_info_user(s, p)
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 
 struct compat_snd_pcm_status64 {
 	snd_pcm_state_t state;
@@ -373,7 +373,7 @@ static int snd_pcm_ioctl_xfern_compat(struct snd_pcm_substream *substream,
 	return err;
 }
 
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 /* X32 ABI has 64bit timespec and 64bit alignment */
 struct snd_pcm_mmap_status_x32 {
 	snd_pcm_state_t state;
@@ -464,7 +464,7 @@ static int snd_pcm_ioctl_sync_ptr_x32(struct snd_pcm_substream *substream,
 
 	return 0;
 }
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 
 /*
  */
@@ -484,10 +484,10 @@ enum {
 	SNDRV_PCM_IOCTL_READN_FRAMES32 = _IOR('A', 0x53, struct snd_xfern32),
 	SNDRV_PCM_IOCTL_STATUS_COMPAT64 = _IOR('A', 0x20, struct compat_snd_pcm_status64),
 	SNDRV_PCM_IOCTL_STATUS_EXT_COMPAT64 = _IOWR('A', 0x24, struct compat_snd_pcm_status64),
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 	SNDRV_PCM_IOCTL_CHANNEL_INFO_X32 = _IOR('A', 0x32, struct snd_pcm_channel_info),
 	SNDRV_PCM_IOCTL_SYNC_PTR_X32 = _IOWR('A', 0x23, struct snd_pcm_sync_ptr_x32),
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 };
 
 static long snd_pcm_ioctl_compat(struct file *file, unsigned int cmd, unsigned long arg)
@@ -531,10 +531,10 @@ static long snd_pcm_ioctl_compat(struct file *file, unsigned int cmd, unsigned l
 	case __SNDRV_PCM_IOCTL_SYNC_PTR32:
 		return snd_pcm_common_ioctl(file, substream, cmd, argp);
 	case __SNDRV_PCM_IOCTL_SYNC_PTR64:
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 		if (in_x32_syscall())
 			return snd_pcm_ioctl_sync_ptr_x32(substream, argp);
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 		return snd_pcm_common_ioctl(file, substream, cmd, argp);
 	case SNDRV_PCM_IOCTL_HW_REFINE32:
 		return snd_pcm_ioctl_hw_params_compat(substream, 1, argp);
@@ -566,10 +566,10 @@ static long snd_pcm_ioctl_compat(struct file *file, unsigned int cmd, unsigned l
 		return snd_pcm_status_user_compat64(substream, argp, false);
 	case SNDRV_PCM_IOCTL_STATUS_EXT_COMPAT64:
 		return snd_pcm_status_user_compat64(substream, argp, true);
-#ifdef CONFIG_X86_X32
+#ifdef CONFIG_X86_X32_ABI
 	case SNDRV_PCM_IOCTL_CHANNEL_INFO_X32:
 		return snd_pcm_ioctl_channel_info_x32(substream, argp);
-#endif /* CONFIG_X86_X32 */
+#endif /* CONFIG_X86_X32_ABI */
 	}
 
 	return -ENOIOCTLCMD;
-- 
2.27.0

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