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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: Andy 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2015-10-05 17:48:05 -07:00 committed by Ingo Molnar
parent 2ec67971fa
commit 8169aff611
3 changed files with 20 additions and 40 deletions
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6
arch/x86/entry/entry_64.S
View File

@ -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

42
arch/x86/entry/entry_64_compat.S
View File

@ -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

12
arch/x86/entry/syscalls/syscall_32.tbl
View File

@ -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