linux.git/arch/x86/include/asm/syscall_wrapper.h, branch v6.0

x86: Remove toolchain check for X32 ABI capability

2022-03-15T09:32:48+00:00

Commit 0bf6276392e9 ("x32: Warn and disable rather than error if
binutils too old") added a small test in arch/x86/Makefile because
binutils 2.22 or newer is needed to properly support elf32-x86-64. This
check is no longer necessary, as the minimum supported version of
binutils is 2.23, which is enforced at configuration time with
scripts/min-tool-version.sh.

Remove this check and replace all uses of CONFIG_X86_X32 with
CONFIG_X86_X32_ABI, as two symbols are no longer necessary.

[nathan: Rebase, fix up a few places where CONFIG_X86_X32 was still
         used, and simplify commit message to satisfy -tip requirements]

Signed-off-by: Masahiro Yamada 
Signed-off-by: Nathan Chancellor 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20220314194842.3452-2-nathan@kernel.org

x86/entry/x32: Rename __x32_compat_sys_* to __x64_compat_sys_*

2021-05-20T13:03:58+00:00

The SYSCALL macros are mapped to symbols as follows:

  __SYSCALL_COMMON(nr, sym)  -->  __x64_
  __SYSCALL_X32(nr, sym)     -->  __x32_

Originally, the syscalls in the x32 special range (512-547) were all
compat.

This assumption is now broken after the following commits:

  55db9c0e8534 ("net: remove compat_sys_{get,set}sockopt")
  5f764d624a89 ("fs: remove the compat readv/writev syscalls")
  598b3cec831f ("fs: remove compat_sys_vmsplice")
  c3973b401ef2 ("mm: remove compat_process_vm_{readv,writev}")

Those commits redefined __x32_sys_* to __x64_sys_* because there is no stub
like __x32_sys_*.

Defining them as follows is more sensible and cleaner.

  __SYSCALL_COMMON(nr, sym)  -->  __x64_
  __SYSCALL_X32(nr, sym)     -->  __x64_

This works because both x86_64 and x32 use the same ABI (RDI, RSI, RDX,
R10, R8, R9)

The ugly #define __x32_sys_* will go away.

Signed-off-by: Masahiro Yamada 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20210517073815.97426-2-masahiroy@kernel.org

x86/syscalls: Fix -Wmissing-prototypes warnings from COND_SYSCALL()

2021-03-25T15:20:41+00:00

Building kernel/sys_ni.c with W=1 emits tons of -Wmissing-prototypes warnings:

  $ make W=1 kernel/sys_ni.o
    [ snip ]
    CC      kernel/sys_ni.o
     ./arch/x86/include/asm/syscall_wrapper.h:83:14: warning: no previous prototype for '__ia32_sys_io_setup' [-Wmissing-prototypes]
     ...

The problem is in __COND_SYSCALL(), the __SYS_STUB0() and __SYS_STUBx() macros
defined a few lines above already have forward declarations.

Let's do likewise for __COND_SYSCALL() to fix the warnings.

Signed-off-by: Masahiro Yamada 
Signed-off-by: Ingo Molnar 
Tested-by: Mickaël Salaün 
Link: https://lore.kernel.org/r/20210301131533.64671-2-masahiroy@kernel.org

x86/entry: Fix build error x86 with !CONFIG_POSIX_TIMERS

2020-03-25T09:06:20+00:00

Add missing semicolon.

Fixes: a74d187c2df3 ("x86/entry: Refactor SYS_NI macros")
Reported-by: Ingo Molnar 
Signed-off-by: Brian Gerst 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20200324143520.898733-1-brgerst@gmail.com

x86/entry: Drop asmlinkage from syscalls

2020-03-21T15:03:25+00:00

asmlinkage is no longer required since the syscall ABI is now fully under
x86 architecture control.  This makes the 32-bit native syscalls a bit more
effecient by passing in regs via EAX instead of on the stack.

Signed-off-by: Brian Gerst 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Dominik Brodowski 
Reviewed-by: Andy Lutomirski 
Link: https://lkml.kernel.org/r/20200313195144.164260-18-brgerst@gmail.com

x86/entry/32: Enable pt_regs based syscalls

2020-03-21T15:03:24+00:00

Enable pt_regs based syscalls for 32-bit.  This makes the 32-bit native
kernel consistent with the 64-bit kernel, and improves the syscall
interface by not needing to push all 6 potential arguments onto the stack.

Signed-off-by: Brian Gerst 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Dominik Brodowski 
Link: https://lkml.kernel.org/r/20200313195144.164260-17-brgerst@gmail.com

x86/entry/64: Move sys_ni_syscall stub to common.c

2020-03-21T15:03:20+00:00

so it can be available to multiple syscall tables.  Also directly return
-ENOSYS instead of bouncing to the generic sys_ni_syscall().

Signed-off-by: Brian Gerst 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20200313195144.164260-7-brgerst@gmail.com

x86/entry: Refactor SYS_NI macros

2020-03-21T15:03:20+00:00

Pull the common code out from the SYS_NI macros into a new __SYS_NI macro.
Also conditionalize the X64 version in preparation for enabling syscall
wrappers on 32-bit native kernels.

Signed-off-by: Brian Gerst 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Dominik Brodowski 
Reviewed-by: Andy Lutomirski 
Link: https://lkml.kernel.org/r/20200313195144.164260-5-brgerst@gmail.com

x86/entry: Refactor COND_SYSCALL macros

2020-03-21T15:03:19+00:00

Pull the common code out from the COND_SYSCALL macros into a new
__COND_SYSCALL macro.  Also conditionalize the X64 version in preparation
for enabling syscall wrappers on 32-bit native kernels.

Signed-off-by: Brian Gerst 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Dominik Brodowski 
Reviewed-by: Andy Lutomirski 
Link: https://lkml.kernel.org/r/20200313195144.164260-4-brgerst@gmail.com

x86/entry: Refactor SYSCALL_DEFINE0 macros

2020-03-21T15:03:19+00:00

Pull the common code out from the SYSCALL_DEFINE0 macros into a new
__SYS_STUB0 macro.  Also conditionalize the X64 version in preparation for
enabling syscall wrappers on 32-bit native kernels.

Signed-off-by: Brian Gerst 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Dominik Brodowski 
Reviewed-by: Andy Lutomirski 
Link: https://lkml.kernel.org/r/20200313195144.164260-3-brgerst@gmail.com