forked from Minki/linux
778843f934
Use of a temporary R8 register here seems to be unnecessary. "push %r8" is a two-byte insn (it needs REX prefix to specify R8), "push $0" is two-byte too. It seems just using the latter would be no worse. Thus, code had an unnecessary "xorq %r8,%r8" insn. It probably costs nothing in execution time here since we are probably limited by store bandwidth at this point, but still. Run-tested under QEMU: 32-bit calls still work: / # ./test_syscall_vdso32 [RUN] Executing 6-argument 32-bit syscall via VDSO [OK] Arguments are preserved across syscall [NOTE] R11 has changed:0000000000200ed7 - assuming clobbered by SYSRET insn [OK] R8..R15 did not leak kernel data [RUN] Executing 6-argument 32-bit syscall via INT 80 [OK] Arguments are preserved across syscall [OK] R8..R15 did not leak kernel data [RUN] Running tests under ptrace [RUN] Executing 6-argument 32-bit syscall via VDSO [OK] Arguments are preserved across syscall [NOTE] R11 has changed:0000000000200ed7 - assuming clobbered by SYSRET insn [OK] R8..R15 did not leak kernel data [RUN] Executing 6-argument 32-bit syscall via INT 80 [OK] Arguments are preserved across syscall [OK] R8..R15 did not leak kernel data Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Drewry <wad@chromium.org> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1462201010-16846-1-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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| .. | ||
| boot | ||
| configs | ||
| crypto | ||
| entry | ||
| events | ||
| ia32 | ||
| include | ||
| kernel | ||
| kvm | ||
| lguest | ||
| lib | ||
| math-emu | ||
| mm | ||
| net | ||
| oprofile | ||
| pci | ||
| platform | ||
| power | ||
| purgatory | ||
| ras | ||
| realmode | ||
| tools | ||
| um | ||
| video | ||
| xen | ||
| .gitignore | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.cpu | ||
| Kconfig.debug | ||
| Makefile | ||
| Makefile_32.cpu | ||
| Makefile.um | ||