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Commit 8169aff6 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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x86/entry/64/compat: Set up full pt_regs for all compat syscalls 



This is conceptually simpler.  More importantly, it eliminates
the PTREGSCALL and execve stubs, which were not compatible with
the C ABI.  This means that C code can call through the compat
syscall table.

The execve stubs are a bit subtle.  They did two things: they
cleared some registers and they forced slow-path return.
Neither is necessary any more: elf_common_init clears the extra
registers and start_thread calls force_iret().

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: 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>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/f95b7f7dfaacf88a8cae85bb06226cae53769287.1444091584.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 2ec67971

arch/x86/entry/entry_64.S

+1 −5
Original line number Diff line number Diff line
@@ -391,20 +391,16 @@ GLOBAL(stub_execveat) 
	jmp	return_from_execve

END(stub_execveat)



#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)

#if defined(CONFIG_X86_X32_ABI)

	.align	8

GLOBAL(stub_x32_execve)

GLOBAL(stub32_execve)

	call	compat_sys_execve

	jmp	return_from_execve

END(stub32_execve)

END(stub_x32_execve)

	.align	8

GLOBAL(stub_x32_execveat)

GLOBAL(stub32_execveat)

	call	compat_sys_execveat

	jmp	return_from_execve

END(stub32_execveat)

END(stub_x32_execveat)

#endif

arch/x86/entry/entry_64_compat.S

+13 −29
Original line number Diff line number Diff line
@@ -219,12 +219,18 @@ ENTRY(entry_INT80_compat) 
	pushq	%rdx			/* pt_regs->dx */

	pushq	%rcx			/* pt_regs->cx */

	pushq	$-ENOSYS		/* pt_regs->ax */

	pushq	$0			/* pt_regs->r8 */

	pushq	$0			/* pt_regs->r9 */

	pushq	$0			/* pt_regs->r10 */

	pushq	$0			/* pt_regs->r11 */

	xorq    %r8,%r8

	pushq   %r8                     /* pt_regs->r8  = 0 */

	pushq   %r8                     /* pt_regs->r9  = 0 */

	pushq   %r8                     /* pt_regs->r10 = 0 */

	pushq   %r8                     /* pt_regs->r11 = 0 */

	pushq   %rbx                    /* pt_regs->rbx */

	pushq   %rbp                    /* pt_regs->rbp */

	pushq   %r12                    /* pt_regs->r12 */

	pushq   %r13                    /* pt_regs->r13 */

	pushq   %r14                    /* pt_regs->r14 */

	pushq   %r15                    /* pt_regs->r15 */

	cld

	sub	$(6*8), %rsp /* pt_regs->bp, bx, r12-15 not saved */



	orl	$TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)

	testl	$_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
@@ -243,10 +249,10 @@ ia32_do_call: 
	call	*ia32_sys_call_table(, %rax, 8)

	movq	%rax, RAX(%rsp)

1:

	RESTORE_EXTRA_REGS

	jmp	int_ret_from_sys_call



ia32_tracesys:

	SAVE_EXTRA_REGS

	movq	%rsp, %rdi			/* &pt_regs -> arg1 */

	call	syscall_trace_enter

	/*
@@ -261,25 +267,11 @@ ia32_tracesys: 
	movl	RSI(%rsp), %esi

	movl	RDI(%rsp), %edi

	movl	%eax, %eax		/* zero extension */

	RESTORE_EXTRA_REGS

	jmp	ia32_do_call

END(entry_INT80_compat)



	.macro PTREGSCALL label, func

	ALIGN

GLOBAL(\label)

	leaq	\func(%rip), %rax

	jmp	ia32_ptregs_common

	.endm



	PTREGSCALL stub32_rt_sigreturn,	sys32_rt_sigreturn

	PTREGSCALL stub32_sigreturn,	sys32_sigreturn

	PTREGSCALL stub32_fork,		sys_fork

	PTREGSCALL stub32_vfork,	sys_vfork



	ALIGN

GLOBAL(stub32_clone)

	leaq	sys_clone(%rip), %rax

	/*

	 * The 32-bit clone ABI is: clone(..., int tls_val, int *child_tidptr).

	 * The 64-bit clone ABI is: clone(..., int *child_tidptr, int tls_val).
@@ -288,12 +280,4 @@ GLOBAL(stub32_clone) 
	 * so we need to swap arguments here before calling it:

	 */

	xchg	%r8, %rcx

	jmp	ia32_ptregs_common



	ALIGN

ia32_ptregs_common:

	SAVE_EXTRA_REGS 8

	call	*%rax

	RESTORE_EXTRA_REGS 8

	ret

END(ia32_ptregs_common)
 
	jmp	sys_clone

arch/x86/entry/syscalls/syscall_32.tbl

+6 −6
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ 
#

0	i386	restart_syscall		sys_restart_syscall

1	i386	exit			sys_exit

2	i386	fork			sys_fork			stub32_fork

2	i386	fork			sys_fork			sys_fork

3	i386	read			sys_read

4	i386	write			sys_write

5	i386	open			sys_open			compat_sys_open
@@ -17,7 +17,7 @@ 
8	i386	creat			sys_creat

9	i386	link			sys_link

10	i386	unlink			sys_unlink

11	i386	execve			sys_execve			stub32_execve

11	i386	execve			sys_execve			compat_sys_execve

12	i386	chdir			sys_chdir

13	i386	time			sys_time			compat_sys_time

14	i386	mknod			sys_mknod
@@ -125,7 +125,7 @@ 
116	i386	sysinfo			sys_sysinfo			compat_sys_sysinfo

117	i386	ipc			sys_ipc				compat_sys_ipc

118	i386	fsync			sys_fsync

119	i386	sigreturn		sys_sigreturn			stub32_sigreturn

119	i386	sigreturn		sys_sigreturn			sys32_sigreturn

120	i386	clone			sys_clone			stub32_clone

121	i386	setdomainname		sys_setdomainname

122	i386	uname			sys_newuname
@@ -179,7 +179,7 @@ 
170	i386	setresgid		sys_setresgid16

171	i386	getresgid		sys_getresgid16

172	i386	prctl			sys_prctl

173	i386	rt_sigreturn		sys_rt_sigreturn		stub32_rt_sigreturn

173	i386	rt_sigreturn		sys_rt_sigreturn		sys32_rt_sigreturn

174	i386	rt_sigaction		sys_rt_sigaction		compat_sys_rt_sigaction

175	i386	rt_sigprocmask		sys_rt_sigprocmask

176	i386	rt_sigpending		sys_rt_sigpending		compat_sys_rt_sigpending
@@ -196,7 +196,7 @@ 
187	i386	sendfile		sys_sendfile			compat_sys_sendfile

188	i386	getpmsg

189	i386	putpmsg

190	i386	vfork			sys_vfork			stub32_vfork

190	i386	vfork			sys_vfork			sys_vfork

191	i386	ugetrlimit		sys_getrlimit			compat_sys_getrlimit

192	i386	mmap2			sys_mmap_pgoff

193	i386	truncate64		sys_truncate64			sys32_truncate64
@@ -364,7 +364,7 @@ 
355	i386	getrandom		sys_getrandom

356	i386	memfd_create		sys_memfd_create

357	i386	bpf			sys_bpf

358	i386	execveat		sys_execveat			stub32_execveat

358	i386	execveat		sys_execveat			compat_sys_execveat

359	i386	socket			sys_socket

360	i386	socketpair		sys_socketpair

361	i386	bind			sys_bind