[PATCH RFC] x86: remove toolchain check for X32 ABI capability

From: Masahiro Yamada
Date: Sat Feb 27 2021 - 13:50:01 EST

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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@xxxxxxxxxx>
---

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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