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Commit 46eabf06 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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x86/entry/64: Call all native slow-path syscalls with full pt-regs 



This removes all of the remaining asm syscall stubs except for
stub_ptregs_64.  Entries in the main syscall table are now all
callable from C.

The resulting asm is every bit as ridiculous as it looks.  The
next few patches will clean it up.  This patch is here to let
reviewers rest their brains and for bisection.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a6b3801be0d505d50aefabda02d3b93efbfc9c73.1454022279.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 302f5b26

arch/x86/entry/entry_64.S

+1 −78
Original line number Diff line number Diff line
@@ -253,7 +253,6 @@ tracesys: 
	 * the value it wants us to use in the table lookup.

	 */

	RESTORE_C_REGS_EXCEPT_RAX

	RESTORE_EXTRA_REGS

#if __SYSCALL_MASK == ~0

	cmpq	$__NR_syscall_max, %rax

#else
@@ -264,6 +263,7 @@ tracesys: 
	movq	%r10, %rcx			/* fixup for C */

	call	*sys_call_table(, %rax, 8)

	movq	%rax, RAX(%rsp)

	RESTORE_EXTRA_REGS

1:

	/* Use IRET because user could have changed pt_regs->foo */
@@ -384,83 +384,6 @@ END(ptregs_\func) 
#define __SYSCALL_64(nr, sym, qual) __SYSCALL_64_QUAL_##qual(sym)

#include <asm/syscalls_64.h>



	.macro FORK_LIKE func

ENTRY(stub_\func)

	SAVE_EXTRA_REGS 8

	jmp	sys_\func

END(stub_\func)

	.endm



	FORK_LIKE  clone

	FORK_LIKE  fork

	FORK_LIKE  vfork



ENTRY(stub_execve)

	call	sys_execve

return_from_execve:

	testl	%eax, %eax

	jz	1f

	/* exec failed, can use fast SYSRET code path in this case */

	ret

1:

	/* must use IRET code path (pt_regs->cs may have changed) */

	addq	$8, %rsp

	ZERO_EXTRA_REGS

	movq	%rax, RAX(%rsp)

	jmp	int_ret_from_sys_call

END(stub_execve)

/*

 * Remaining execve stubs are only 7 bytes long.

 * ENTRY() often aligns to 16 bytes, which in this case has no benefits.

 */

	.align	8

GLOBAL(stub_execveat)

	call	sys_execveat

	jmp	return_from_execve

END(stub_execveat)



#if defined(CONFIG_X86_X32_ABI)

	.align	8

GLOBAL(stub_x32_execve)

	call	compat_sys_execve

	jmp	return_from_execve

END(stub_x32_execve)

	.align	8

GLOBAL(stub_x32_execveat)

	call	compat_sys_execveat

	jmp	return_from_execve

END(stub_x32_execveat)

#endif



/*

 * sigreturn is special because it needs to restore all registers on return.

 * This cannot be done with SYSRET, so use the IRET return path instead.

 */

ENTRY(stub_rt_sigreturn)

	/*

	 * SAVE_EXTRA_REGS result is not normally needed:

	 * sigreturn overwrites all pt_regs->GPREGS.

	 * But sigreturn can fail (!), and there is no easy way to detect that.

	 * To make sure RESTORE_EXTRA_REGS doesn't restore garbage on error,

	 * we SAVE_EXTRA_REGS here.

	 */

	SAVE_EXTRA_REGS 8

	call	sys_rt_sigreturn

return_from_stub:

	addq	$8, %rsp

	RESTORE_EXTRA_REGS

	movq	%rax, RAX(%rsp)

	jmp	int_ret_from_sys_call

END(stub_rt_sigreturn)



#ifdef CONFIG_X86_X32_ABI

ENTRY(stub_x32_rt_sigreturn)

	SAVE_EXTRA_REGS 8

	call	sys32_x32_rt_sigreturn

	jmp	return_from_stub

END(stub_x32_rt_sigreturn)

#endif



/*

 * A newly forked process directly context switches into this address.

 *

arch/x86/entry/syscalls/syscall_64.tbl

+9 −9
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ 
12	common	brk			sys_brk

13	64	rt_sigaction		sys_rt_sigaction

14	common	rt_sigprocmask		sys_rt_sigprocmask

15	64	rt_sigreturn		stub_rt_sigreturn/ptregs

15	64	rt_sigreturn		sys_rt_sigreturn/ptregs

16	64	ioctl			sys_ioctl

17	common	pread64			sys_pread64

18	common	pwrite64		sys_pwrite64
@@ -62,10 +62,10 @@ 
53	common	socketpair		sys_socketpair

54	64	setsockopt		sys_setsockopt

55	64	getsockopt		sys_getsockopt

56	common	clone			stub_clone/ptregs

57	common	fork			stub_fork/ptregs

58	common	vfork			stub_vfork/ptregs

59	64	execve			stub_execve/ptregs

56	common	clone			sys_clone/ptregs

57	common	fork			sys_fork/ptregs

58	common	vfork			sys_vfork/ptregs

59	64	execve			sys_execve/ptregs

60	common	exit			sys_exit

61	common	wait4			sys_wait4

62	common	kill			sys_kill
@@ -328,7 +328,7 @@ 
319	common	memfd_create		sys_memfd_create

320	common	kexec_file_load		sys_kexec_file_load

321	common	bpf			sys_bpf

322	64	execveat		stub_execveat/ptregs

322	64	execveat		sys_execveat/ptregs

323	common	userfaultfd		sys_userfaultfd

324	common	membarrier		sys_membarrier

325	common	mlock2			sys_mlock2
@@ -339,14 +339,14 @@ 
# for native 64-bit operation.

#

512	x32	rt_sigaction		compat_sys_rt_sigaction

513	x32	rt_sigreturn		stub_x32_rt_sigreturn

513	x32	rt_sigreturn		sys32_x32_rt_sigreturn

514	x32	ioctl			compat_sys_ioctl

515	x32	readv			compat_sys_readv

516	x32	writev			compat_sys_writev

517	x32	recvfrom		compat_sys_recvfrom

518	x32	sendmsg			compat_sys_sendmsg

519	x32	recvmsg			compat_sys_recvmsg

520	x32	execve			stub_x32_execve/ptregs

520	x32	execve			compat_sys_execve/ptregs

521	x32	ptrace			compat_sys_ptrace

522	x32	rt_sigpending		compat_sys_rt_sigpending

523	x32	rt_sigtimedwait		compat_sys_rt_sigtimedwait
@@ -371,4 +371,4 @@ 
542	x32	getsockopt		compat_sys_getsockopt

543	x32	io_setup		compat_sys_io_setup

544	x32	io_submit		compat_sys_io_submit

545	x32	execveat		stub_x32_execveat/ptregs
 
545	x32	execveat		compat_sys_execveat/ptregs