05 Apr, 2018
2 commits
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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 -
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/* 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
retqThe 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 Torvaldsand 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
30 Jan, 2018
1 commit
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The SYCALLL64 fast path was a nice, if small, optimization back in the good
old days when syscalls were actually reasonably fast. Now there is PTI to
slow everything down, and indirect branches are verboten, making everything
messier. The retpoline code in the fast path is particularly nasty.Just get rid of the fast path. The slow path is barely slower.
[ tglx: Split out the 'push all extra regs' part ]
Signed-off-by: Andy Lutomirski
Signed-off-by: Thomas Gleixner
Acked-by: Ingo Molnar
Cc: Borislav Petkov
Cc: Linus Torvalds
Cc: Kernel Hardening
Link: https://lkml.kernel.org/r/462dff8d4d64dfbfc851fbf3130641809d980ecd.1517164461.git.luto@kernel.org
02 Nov, 2017
1 commit
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
29 Jan, 2016
4 commits
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64-bit syscalls currently have an optimization in which they are
called with partial pt_regs. A small handful require full
pt_regs.In the 32-bit and compat cases, I cleaned this up by forcing
full pt_regs for all syscalls. The performance hit doesn't
really matter as the affected system calls are fundamentally
heavy and this is the 32-bit compat case.I want to clean up the 64-bit case as well, but I don't want to
hurt fast path performance. To do that, I want to force the
syscalls that use pt_regs onto the slow path. This will enable
us to make slow path syscalls be real ABI-compliant C functions.Use the new syscall entry qualification machinery for this.
'stub_clone' is now 'stub_clone/ptregs'.The next patch will eliminate the stubs, and we'll just have
'sys_clone/ptregs'.As of this patch, two-phase entry tracing is no longer used. It
has served its purpose (namely a huge speedup on some workloads
prior to more general opportunistic SYSRET support), and once
the dust settles I'll send patches to back it out.The implementation is heavily based on a patch from Brian Gerst:
http://lkml.kernel.org/g/1449666173-15366-1-git-send-email-brgerst@gmail.com
Originally-From: Brian Gerst
Signed-off-by: Andy Lutomirski
Cc: Andy Lutomirski
Cc: Borislav Petkov
Cc: Denys Vlasenko
Cc: Frederic Weisbecker
Cc: Frédéric Weisbecker
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Linux Kernel Mailing List
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/b9beda88460bcefec6e7d792bd44eca9b760b0c4.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar -
This will let us specify something like 'sys_xyz/foo' instead of
'sys_xyz' in the syscall table, where the 'foo' qualifier conveys
some extra information to the C code.The intent is to allow things like sys_execve/ptregs to indicate
that sys_execve() touches pt_regs.Signed-off-by: Andy Lutomirski
Cc: Andy Lutomirski
Cc: Borislav Petkov
Cc: Brian Gerst
Cc: Denys Vlasenko
Cc: Frederic Weisbecker
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/2de06e33dce62556b3ec662006fcb295504e296e.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar -
Rather than duplicating the compat entry handling in all
consumers of syscalls_BITS.h, handle it directly in
syscalltbl.sh. Now we generate entries in syscalls_32.h like:__SYSCALL_I386(5, sys_open)
__SYSCALL_I386(5, compat_sys_open)and all of its consumers implicitly get the right entry point.
Signed-off-by: Andy Lutomirski
Cc: Andy Lutomirski
Cc: Borislav Petkov
Cc: Brian Gerst
Cc: Denys Vlasenko
Cc: Frederic Weisbecker
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/b7c2b501dc0e6e43050e916b95807c3e2e16e9bb.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar -
The common/64/x32 distinction has no effect other than
determining which kernels actually support the syscall. Move
the logic into syscalltbl.sh.Signed-off-by: Andy Lutomirski
Cc: Andy Lutomirski
Cc: Borislav Petkov
Cc: Brian Gerst
Cc: Denys Vlasenko
Cc: Frederic Weisbecker
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/58d4a95f40e43b894f93288b4a3633963d0ee22e.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar
09 Oct, 2015
1 commit
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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
04 Jun, 2015
1 commit
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The vsyscall code is entry code too, so move it to arch/x86/entry/vsyscall/.
Cc: Borislav Petkov
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Thomas Gleixner
Cc: Andy Lutomirski
Cc: Denys Vlasenko
Cc: Brian Gerst
Cc: Peter Zijlstra
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar
