linux-toradex.git/arch/x86/include/asm/syscall.h, branch v4.19

syscalls/x86: Unconditionally enable 'struct pt_regs' based syscalls on x86_64

2018-04-05T14:59:38+00:00

Removing CONFIG_SYSCALL_PTREGS from arch/x86/Kconfig and simply selecting
ARCH_HAS_SYSCALL_WRAPPER unconditionally on x86-64 allows us to simplify
several codepaths.

Signed-off-by: Dominik Brodowski 
Acked-by: Linus Torvalds 
Cc: Al Viro 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20180405095307.3730-7-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar

syscalls/x86: Use 'struct pt_regs' based syscall calling convention for 64-bit syscalls

2018-04-05T14:59:26+00:00

Let's make use of ARCH_HAS_SYSCALL_WRAPPER=y on pure 64-bit x86-64 systems:

Each syscall defines a stub which takes struct pt_regs as its only
argument. It decodes just those parameters it needs, e.g:

	asmlinkage long sys_xyzzy(const struct pt_regs *regs)
	{
		return SyS_xyzzy(regs->di, regs->si, regs->dx);
	}

This approach avoids leaking random user-provided register content down
the call chain.

For example, for sys_recv() which is a 4-parameter syscall, the assembly
now is (in slightly reordered fashion):

	:
		callq	<__fentry__>

		/* decode regs->di, ->si, ->dx and ->r10 */
		mov	0x70(%rdi),%rdi
		mov	0x68(%rdi),%rsi
		mov	0x60(%rdi),%rdx
		mov	0x38(%rdi),%rcx

		[ SyS_recv() is automatically inlined by the compiler,
		  as it is not [yet] used anywhere else ]
		/* clear %r9 and %r8, the 5th and 6th args */
		xor	%r9d,%r9d
		xor	%r8d,%r8d

		/* do the actual work */
		callq	__sys_recvfrom

		/* cleanup and return */
		cltq
		retq

The only valid place in an x86-64 kernel which rightfully calls
a syscall function on its own -- vsyscall -- needs to be modified
to pass struct pt_regs onwards as well.

To keep the syscall table generation working independent of
SYSCALL_PTREGS being enabled, the stubs are named the same as the
"original" syscall stubs, i.e. sys_*().

This patch is based on an original proof-of-concept

 | From: Linus Torvalds 
 | Signed-off-by: Linus Torvalds 

and was split up and heavily modified by me, in particular to base it on
ARCH_HAS_SYSCALL_WRAPPER, to limit it to 64-bit-only for the time being,
and to update the vsyscall to the new calling convention.

Signed-off-by: Dominik Brodowski 
Acked-by: Linus Torvalds 
Cc: Al Viro 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20180405095307.3730-4-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar

x86/asm: Move 'status' from thread_struct to thread_info

2018-01-30T14:30:36+00:00

The TS_COMPAT bit is very hot and is accessed from code paths that mostly
also touch thread_info::flags.  Move it into struct thread_info to improve
cache locality.

The only reason it was in thread_struct is that there was a brief period
during which arch-specific fields were not allowed in struct thread_info.

Linus suggested further changing:

  ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED);

to:

  if (unlikely(ti->status & (TS_COMPAT|TS_I386_REGS_POKED)))
          ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED);

on the theory that frequently dirtying the cacheline even in pure 64-bit
code that never needs to modify status hurts performance.  That could be a
reasonable followup patch, but I suspect it matters less on top of this
patch.

Suggested-by: Linus Torvalds 
Signed-off-by: Andy Lutomirski 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Ingo Molnar 
Acked-by: Linus Torvalds 
Cc: Borislav Petkov 
Cc: Kernel Hardening 
Link: https://lkml.kernel.org/r/03148bcc1b217100e6e8ecf6a5468c45cf4304b6.1517164461.git.luto@kernel.org

x86/asm: Move the thread_info::status field to thread_struct

2016-09-15T06:25:12+00:00

Because sched.h and thread_info.h are a tangled mess, I turned
in_compat_syscall() into a macro.  If we had current_thread_struct()
or similar and we could use it from thread_info.h, then this would
be a bit cleaner.

Signed-off-by: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Jann Horn 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/ccc8a1b2f41f9c264a41f771bb4a6539a642ad72.1473801993.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86/ptrace: Stop setting TS_COMPAT in ptrace code

2016-07-27T09:09:43+00:00

Setting TS_COMPAT in ptrace is wrong: if we happen to do it during
syscall entry, then we'll confuse seccomp and audit.  (The former
isn't a security problem: seccomp is currently entirely insecure if a
malicious ptracer is attached.)  As a minimal fix, this patch adds a
new flag TS_I386_REGS_POKED that handles the ptrace special case.

Signed-off-by: Andy Lutomirski 
Acked-by: Oleg Nesterov 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/5383ebed38b39fa37462139e337aff7f2314d1ca.1469599803.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86/syscalls: Give sys_call_ptr_t a useful type

2015-10-09T07:41:08+00:00

Syscalls are asmlinkage functions (on 32-bit kernels), take six
args of type unsigned long, and return long.  Note that uml
could probably be slightly cleaned up on top of this patch.

Signed-off-by: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/4d3ecc4a169388d47009175408b2961961744e6f.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86/entry/syscalls: Move syscall table declarations into asm/syscalls.h

2015-10-09T07:41:08+00:00

The header was missing some compat declarations.

Also make sys_call_ptr_t have a consistent type.

Signed-off-by: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/3166aaff0fb43897998fcb6ef92991533f8c5c6c.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar

audit: use uapi/linux/audit.h for AUDIT_ARCH declarations

2014-03-20T14:11:59+00:00

The syscall.h headers were including linux/audit.h but really only
needed the uapi/linux/audit.h to get the requisite defines.  Switch to
the uapi headers.

Signed-off-by: Eric Paris 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@linux-mips.org
Cc: linux-s390@vger.kernel.org
Cc: x86@kernel.org

syscall_get_arch: remove useless function arguments

2014-03-20T14:11:59+00:00

Every caller of syscall_get_arch() uses current for the task and no
implementors of the function need args.  So just get rid of both of
those things.  Admittedly, since these are inline functions we aren't
wasting stack space, but it just makes the prototypes better.

Signed-off-by: Eric Paris 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@linux-mips.org
Cc: linux390@de.ibm.com
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-arch@vger.kernel.org

x86: Fix sys_call_table type in asm/syscall.h

2013-08-06T21:18:08+00:00

Make the sys_call_table type defined in asm/syscall.h match
the definition in syscall_64.c

v2: include asm/syscall.h in syscall_64.c too. I left uml alone
because it doesn't have an syscall.h on its own and including
the native one leads to other errors.

Signed-off-by: Andi Kleen 
Link: http://lkml.kernel.org/r/1375740170-7446-2-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin 
Cc: Richard Weinberger