x86/entry/32: Switch INT80 to the new C syscall path

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/a7e8d8df96838eae3208dd0441023f3ce7a81831.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 13 insertions, 21 deletions

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 36b6beb181f6..02881e528945 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -153,13 +153,13 @@
 
 #endif /* CONFIG_X86_32_LAZY_GS */
 
-.macro SAVE_ALL
+.macro SAVE_ALL pt_regs_ax=%eax
         cld
         PUSH_GS
         pushl   %fs
         pushl   %es
         pushl   %ds
-        pushl   %eax
+        pushl   \pt_regs_ax
         pushl   %ebp
         pushl   %edi
         pushl   %esi
@@ -370,20 +370,17 @@ ENDPROC(entry_SYSENTER_32)
         # system call handler stub
 ENTRY(entry_INT80_32)
         ASM_CLAC
-        pushl   %eax                            # save orig_eax
-        SAVE_ALL
-        GET_THREAD_INFO(%ebp)
-                                                # system call tracing in operation / emulation
-        testl   $_TIF_WORK_SYSCALL_ENTRY, TI_flags(%ebp)
-        jnz     syscall_trace_entry
-        cmpl    $(NR_syscalls), %eax
-        jae     syscall_badsys
-syscall_call:
-        call    *sys_call_table(, %eax, 4)
-syscall_after_call:
-        movl    %eax, PT_EAX(%esp)              # store the return value
-syscall_exit:
-        jmp     syscall_exit_work
+        pushl   %eax                    /* pt_regs->orig_ax */
+        SAVE_ALL pt_regs_ax=$-ENOSYS    /* save rest, load -ENOSYS into ax */
+
+        /*
+         * User mode is traced as though IRQs are on, and the interrupt gate
+         * turned them off.
+         */
+        TRACE_IRQS_OFF
+
+        movl    %esp, %eax
+        call    do_int80_syscall_32
 
 restore_all:
         TRACE_IRQS_IRET
@@ -491,11 +488,6 @@ syscall_fault:
         jmp     resume_userspace
 END(syscall_fault)
 
-syscall_badsys:
-        movl    $-ENOSYS, %eax
-        jmp     syscall_after_call
-END(syscall_badsys)
-
 sysenter_badsys:
         movl    $-ENOSYS, %eax
         jmp     sysenter_after_call