Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1240087

[PATCH v2 22/36] x86/entry: Add C code for fast system call entries

From Andy Lutomirski <luto@kernel.org>
Newsgroups linux.kernel
Subject [PATCH v2 22/36] x86/entry: Add C code for fast system call entries
Date 2015-10-06 03:00 +0200
Message-ID <qgoLO-7cw-49@gated-at.bofh.it> (permalink)
References <qgoC6-715-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

This handles both SYSENTER and SYSCALL.  The asm glue will take care
of the differences.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/entry/common.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 41d17508cf46..1b2606edc621 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -24,6 +24,8 @@
 
 #include <asm/desc.h>
 #include <asm/traps.h>
+#include <asm/vdso.h>
+#include <asm/uaccess.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/syscalls.h>
@@ -360,4 +362,45 @@ __visible void do_int80_syscall_32(struct pt_regs *regs)
 
 	syscall_return_slowpath(regs);
 }
+
+__visible void do_fast_syscall_32(struct pt_regs *regs)
+{
+	/*
+	 * Called using the internal vDSO SYSENTER/SYSCALL32 calling
+	 * convention.  Adjust regs so it looks like we entered using int80.
+	 */
+
+	unsigned long landing_pad = (unsigned long)current->mm->context.vdso +
+		vdso_image_32.sym_int80_landing_pad;
+
+	/*
+	 * SYSENTER loses EIP, and even SYSCALL32 needs us to skip forward
+	 * so that 'regs->ip -= 2' lands back on an int $0x80 instruction.
+	 * Fix it up.
+	 */
+	regs->ip = landing_pad;
+
+	/*
+	 * Fetch ECX from where the vDSO stashed it.
+	 *
+	 * WARNING: We are in CONTEXT_USER and RCU isn't paying attention!
+	 */
+	local_irq_enable();
+	if (get_user(*(u32 *)&regs->cx,
+		     (u32 __user __force *)(unsigned long)(u32)regs->sp)) {
+		/* User code screwed up. */
+		local_irq_disable();
+		regs->ax = -EFAULT;
+#ifdef CONFIG_CONTEXT_TRACKING
+		enter_from_user_mode();
+#endif
+		prepare_exit_to_usermode(regs);
+		return;
+	}
+	local_irq_disable();
+
+	/* Now this is just like a normal syscall. */
+	do_int80_syscall_32(regs);
+	return;
+}
 #endif
-- 
2.4.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
  [PATCH v2 04/36] selftests/x86: Add a test for syscall restart and arg modification Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    [tip:x86/asm] selftests/x86:   Add a test for ptrace syscall restart and arg modification tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-07 18:20 +0200
  [PATCH v2 20/36] x86/entry: Add do_syscall_32, a C function to do 32-bit syscalls Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    [tip:x86/asm] x86/entry: Add do_syscall_32(),   a C function to do 32-bit syscalls tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
  [PATCH v2 13/36] x86/vdso/32: Save extra registers in the INT80 vsyscall path Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    [tip:x86/asm] x86/vdso/32:   Save extra registers in the INT80 vsyscall path tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:10 +0200
  [PATCH v2 11/36] x86/vdso: Replace hex int80 CFI annotations with gas directives Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    [tip:x86/asm] x86/vdso:   Replace hex int80 CFI annotations with GAS directives tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:10 +0200
  [PATCH v2 02/36] x86/uaccess: __chk_range_not_ok is unlikely to return true Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    Re: [PATCH v2 02/36] x86/uaccess: __chk_range_not_ok is unlikely to  return true Borislav Petkov <bp@alien8.de> - 2015-10-07 13:00 +0200
      Re: [PATCH v2 02/36] x86/uaccess: __chk_range_not_ok is unlikely to  return true Ingo Molnar <mingo@kernel.org> - 2015-10-07 18:30 +0200
    [tip:x86/asm] x86/uaccess: Add unlikely() to __chk_range_not_ok()   failure paths tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-07 18:20 +0200
  [PATCH v2 06/36] x86/entry: Move lockdep_sys_exit to prepare_exit_to_usermode Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    [tip:x86/asm] x86/entry, locking/lockdep: Move lockdep_sys_exit()   to prepare_exit_to_usermode() tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-07 18:20 +0200
      Re: [tip:x86/asm] x86/entry, locking/lockdep: Move  lockdep_sys_exit() to prepare_exit_to_usermode() Peter Zijlstra <peterz@infradead.org> - 2015-10-08 11:00 +0200
        Re: [tip:x86/asm] x86/entry, locking/lockdep: Move lockdep_sys_exit()  to prepare_exit_to_usermode() Andy Lutomirski <luto@amacapital.net> - 2015-10-09 21:40 +0200
  [PATCH v2 16/36] x86/entry/64/compat: Remove most of the fast system call machinery Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    [tip:x86/asm] x86/entry/64/compat:   Remove most of the fast system call machinery tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
  [PATCH v2 22/36] x86/entry: Add C code for fast system call entries Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    Re: [PATCH v2 22/36] x86/entry: Add C code for fast system call entries Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-06 10:30 +0200
      Re: [PATCH v2 22/36] x86/entry: Add C code for fast system call entries Andy Lutomirski <luto@amacapital.net> - 2015-10-06 20:30 +0200
    Re: [PATCH v2 22/36] x86/entry: Add C code for fast system call entries Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-06 10:30 +0200
    [tip:x86/asm] x86/entry: Add C code for fast system call entries tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
  [PATCH v2 30/36] x86/entry: Make irqs_disabled checks in exit code depend on lockdep Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    [tip:x86/asm] x86/entry:   Make irqs_disabled checks in exit code depend on lockdep tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
  [PATCH v2 15/36] x86/entry/64/compat: Remove audit optimizations Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    [tip:x86/asm] x86/entry/64/compat: Remove audit optimizations tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
  [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    Re: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall  arg fetch Ingo Molnar <mingo@kernel.org> - 2015-10-09 09:40 +0200
      Re: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall  arg fetch Andy Lutomirski <luto@amacapital.net> - 2015-10-09 21:30 +0200
        Re: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall  arg fetch Ingo Molnar <mingo@kernel.org> - 2015-10-10 11:10 +0200
    [tip:x86/asm] x86/entry:   Micro-optimize compat fast syscall arg fetch tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
  Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-06 10:40 +0200
    Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native  64-bit Ingo Molnar <mingo@kernel.org> - 2015-10-06 11:00 +0200
    Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Andy Lutomirski <luto@amacapital.net> - 2015-10-06 20:30 +0200
  Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native  64-bit Ingo Molnar <mingo@kernel.org> - 2015-10-09 15:10 +0200
    Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Richard Weinberger <richard.weinberger@gmail.com> - 2015-10-12 20:40 +0200
      Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Andy Lutomirski <luto@amacapital.net> - 2015-10-12 20:50 +0200
        Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native  64-bit Richard Weinberger <richard@nod.at> - 2015-10-12 23:10 +0200

csiph-web