From dfe64506c01e57159a4c550fe537c13a317ff01b Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 5 Apr 2018 11:53:00 +0200 Subject: 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 Signed-off-by: Dominik Brodowski 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/20180405095307.3730-2-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar --- arch/x86/entry/common.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'arch/x86/entry/common.c') 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); -- cgit v1.2.3-59-g8ed1b