Commit-ID: dfe64506c01e57159a4c550fe537c13a317ff01b Gitweb: https://git.kernel.org/tip/dfe64506c01e57159a4c550fe537c13a317ff01b Author: Linus Torvalds <torva...@linux-foundation.org> AuthorDate: Thu, 5 Apr 2018 11:53:00 +0200 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 5 Apr 2018 16:59:24 +0200
x86/syscalls: Don't pointlessly reload the system call number We have it in a register in the low-level asm, just pass it in as an argument rather than have do_syscall_64() load it back in from the ptregs pointer. Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Dominik Brodowski <li...@dominikbrodowski.net> Cc: Andy Lutomirski <l...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/20180405095307.3730-2-li...@dominikbrodowski.net Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/entry/common.c | 12 ++++++------ arch/x86/entry/entry_64.S | 3 ++- 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 74f6eee15179..a8b066dbbf48 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -266,14 +266,13 @@ __visible inline void syscall_return_slowpath(struct pt_regs *regs) } #ifdef CONFIG_X86_64 -__visible void do_syscall_64(struct pt_regs *regs) +__visible void do_syscall_64(unsigned long nr, struct pt_regs *regs) { - struct thread_info *ti = current_thread_info(); - unsigned long nr = regs->orig_ax; + struct thread_info *ti; enter_from_user_mode(); local_irq_enable(); - + ti = current_thread_info(); if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) nr = syscall_trace_enter(regs); @@ -282,8 +281,9 @@ __visible void do_syscall_64(struct pt_regs *regs) * table. The only functional difference is the x32 bit in * regs->orig_ax, which changes the behavior of some syscalls. */ - if (likely((nr & __SYSCALL_MASK) < NR_syscalls)) { - nr = array_index_nospec(nr & __SYSCALL_MASK, NR_syscalls); + nr &= __SYSCALL_MASK; + if (likely(nr < NR_syscalls)) { + nr = array_index_nospec(nr, NR_syscalls); regs->ax = sys_call_table[nr]( regs->di, regs->si, regs->dx, regs->r10, regs->r8, regs->r9); diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 936e19642eab..6cfe38665f3c 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -233,7 +233,8 @@ GLOBAL(entry_SYSCALL_64_after_hwframe) TRACE_IRQS_OFF /* IRQs are off. */ - movq %rsp, %rdi + movq %rax, %rdi + movq %rsp, %rsi call do_syscall_64 /* returns with IRQs disabled */ TRACE_IRQS_IRETQ /* we're about to change IF */
