diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-04-05 11:53:00 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-04-05 16:59:24 +0200 |
| commit | dfe64506c01e57159a4c550fe537c13a317ff01b (patch) | |
| tree | 4c5623bfac6ecb60eb36dec94784eda740d11c0f | |
| parent | 642e7fd23353e22290e3d51719fcb658dc252342 (diff) | |
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 <torvalds@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180405095307.3730-2-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/entry/common.c | 12 | ||||
| -rw-r--r-- | 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 */ |