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x86/entry/64/compat: Migrate the body of the syscall entry to C

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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/a2f0fce68feeba798a24339b5a7ec1ec2dd9eaf7.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2015-10-05 17:48:09 -07:00 committed by Ingo Molnar
parent bd2d3a3ba6
commit ee08c6bd31
2 changed files with 19 additions and 39 deletions
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2
arch/x86/entry/entry_64.S
View File

@ -582,7 +582,7 @@ retint_kernel:
* At this label, code paths which return to kernel and to user,
* which come from interrupts/exception and from syscalls, merge.
*/
restore_regs_and_iret:
GLOBAL(restore_regs_and_iret)
RESTORE_EXTRA_REGS
restore_c_regs_and_iret:
RESTORE_C_REGS

56
arch/x86/entry/entry_64_compat.S
View File

@ -202,14 +202,17 @@ END(entry_SYSCALL_compat)
ENTRY(entry_INT80_compat)
/*
* Interrupts are off on entry.
* We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON,
* it is too small to ever cause noticeable irq latency.
*/
PARAVIRT_ADJUST_EXCEPTION_FRAME
SWAPGS
ENABLE_INTERRUPTS(CLBR_NONE)
/* Zero-extending 32-bit regs, do not remove */
/*
* User tracing code (ptrace or signal handlers) might assume that
* the saved RAX contains a 32-bit number when we're invoking a 32-bit
* syscall. Just in case the high bits are nonzero, zero-extend
* the syscall number. (This could almost certainly be deleted
* with no ill effects.)
*/
movl %eax, %eax
/* Construct struct pt_regs on stack (iret frame is already on stack) */
@ -232,42 +235,19 @@ ENTRY(entry_INT80_compat)
pushq %r15 /* pt_regs->r15 */
cld
orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
jnz ia32_tracesys
ia32_do_call:
/* 32-bit syscall -> 64-bit C ABI argument conversion */
movl %edi, %r8d /* arg5 */
movl %ebp, %r9d /* arg6 */
xchg %ecx, %esi /* rsi:arg2, rcx:arg4 */
movl %ebx, %edi /* arg1 */
movl %edx, %edx /* arg3 (zero extension) */
cmpq $(IA32_NR_syscalls-1), %rax
ja 1f
call *ia32_sys_call_table(, %rax, 8)
movq %rax, RAX(%rsp)
1:
RESTORE_EXTRA_REGS
jmp int_ret_from_sys_call
ia32_tracesys:
movq %rsp, %rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
/*
* Reload arg registers from stack in case ptrace changed them.
* Don't reload %eax because syscall_trace_enter() returned
* the %rax value we should see. But do truncate it to 32 bits.
* If it's -1 to make us punt the syscall, then (u32)-1 is still
* an appropriately invalid value.
* User mode is traced as though IRQs are on, and the interrupt
* gate turned them off.
*/
movl RCX(%rsp), %ecx
movl RDX(%rsp), %edx
movl RSI(%rsp), %esi
movl RDI(%rsp), %edi
movl %eax, %eax /* zero extension */
jmp ia32_do_call
TRACE_IRQS_OFF
movq %rsp, %rdi
call do_int80_syscall_32
/* Go back to user mode. */
TRACE_IRQS_ON
SWAPGS
jmp restore_regs_and_iret
END(entry_INT80_compat)
ALIGN