x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER

[linux-2.6-microblaze.git] / arch / x86 / entry / entry_64_compat.S

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 0f974ae..541fdaf 100644 (file)
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -57,29 +57,30 @@ SYM_CODE_START(entry_SYSENTER_compat)
 
        movq    PER_CPU_VAR(cpu_current_top_of_stack), %rsp
 
-       /*
-        * 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 */
        pushq   $__USER32_DS            /* pt_regs->ss */
-       pushq   %rbp                    /* pt_regs->sp (stashed in bp) */
+       pushq   $0                      /* pt_regs->sp = 0 (placeholder) */
 
        /*
         * Push flags.  This is nasty.  First, interrupts are currently
-        * off, but we need pt_regs->flags to have IF set.  Second, even
-        * if TF was set when SYSENTER started, it's clear by now.  We fix
-        * that later using TIF_SINGLESTEP.
+        * off, but we need pt_regs->flags to have IF set.  Second, if TS
+        * was set in usermode, it's still set, and we're singlestepping
+        * through this code.  do_SYSENTER_32() will fix up IF.
         */
        pushfq                          /* pt_regs->flags (except IF = 0) */
-       orl     $X86_EFLAGS_IF, (%rsp)  /* Fix saved flags */
        pushq   $__USER32_CS            /* pt_regs->cs */
        pushq   $0                      /* pt_regs->ip = 0 (placeholder) */
+SYM_INNER_LABEL(entry_SYSENTER_compat_after_hwframe, SYM_L_GLOBAL)
+
+       /*
+        * 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
+
        pushq   %rax                    /* pt_regs->orig_ax */
        pushq   %rdi                    /* pt_regs->di */
        pushq   %rsi                    /* pt_regs->si */
@@ -135,7 +136,7 @@ SYM_CODE_START(entry_SYSENTER_compat)
 .Lsysenter_flags_fixed:
 
        movq    %rsp, %rdi
-       call    do_fast_syscall_32
+       call    do_SYSENTER_32
        /* XEN PV guests always use IRET path */
        ALTERNATIVE "testl %eax, %eax; jz swapgs_restore_regs_and_return_to_usermode", \
                    "jmp swapgs_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV