x86 vDSO: ia32 vdso32-syscall build

This puts the syscall version of the 32-bit vDSO in arch/x86/vdso/vdso32/
for 64-bit IA32 support.  This is not used yet, but it paves the way for
consolidating the 32-bit vDSO source and build logic all in one place.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 76 insertions, 3 deletions

diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 1efe785979a2..1127c716df02 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -71,6 +71,7 @@ $(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE
 #
 obj-$(VDSO32-y)                 += vdso32-syms.lds
 vdso32.so-$(CONFIG_X86_32)      += int80
+vdso32.so-$(CONFIG_COMPAT)      += syscall
 vdso32.so-$(VDSO32-y)           += sysenter
 
 CPPFLAGS_vdso32.lds = $(CPPFLAGS_vdso.lds)
diff --git a/arch/x86/vdso/vdso32/sigreturn.S b/arch/x86/vdso/vdso32/sigreturn.S
index 778f4649e32f..8d65a0a0eb70 100644
--- a/arch/x86/vdso/vdso32/sigreturn.S
+++ b/arch/x86/vdso/vdso32/sigreturn.S
@@ -6,9 +6,12 @@
  * routines are constant for all vsyscall implementations.
  */
 
-#include <asm/unistd.h>
+#include <asm/unistd_32.h>
 #include <asm/asm-offsets.h>
 
+#ifndef SYSCALL_ENTER_KERNEL
+#define SYSCALL_ENTER_KERNEL    int $0x80
+#endif
 
 /* XXX
    Should these be named "_sigtramp" or something?
@@ -22,7 +25,7 @@ __kernel_sigreturn:
 .LSTART_sigreturn:
         popl %eax               /* XXX does this mean it needs unwind info? */
         movl $__NR_sigreturn, %eax
-        int $0x80
+        SYSCALL_ENTER_KERNEL
 .LEND_sigreturn:
         .size __kernel_sigreturn,.-.LSTART_sigreturn
 
@@ -32,7 +35,7 @@ __kernel_sigreturn:
 __kernel_rt_sigreturn:
 .LSTART_rt_sigreturn:
         movl $__NR_rt_sigreturn, %eax
-        int $0x80
+        SYSCALL_ENTER_KERNEL
 .LEND_rt_sigreturn:
         .size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
         .balign 32
diff --git a/arch/x86/vdso/vdso32/syscall.S b/arch/x86/vdso/vdso32/syscall.S
new file mode 100644
index 000000000000..333bfb552c88
--- /dev/null
+++ b/arch/x86/vdso/vdso32/syscall.S
@@ -0,0 +1,69 @@
+/*
+ * Code for the vsyscall page.  This version uses the syscall instruction.
+ */
+
+#include <asm/asm-offsets.h>
+#include <asm/segment.h>
+
+        .text
+        .globl __kernel_vsyscall
+        .type __kernel_vsyscall,@function
+__kernel_vsyscall:
+.LSTART_vsyscall:
+        push    %ebp
+.Lpush_ebp:
+        movl    %ecx, %ebp
+        syscall
+        movl    $__USER32_DS, %ecx
+        movl    %ecx, %ss
+        movl    %ebp, %ecx
+        popl    %ebp
+.Lpop_ebp:
+        ret
+.LEND_vsyscall:
+        .size __kernel_vsyscall,.-.LSTART_vsyscall
+
+        .section .eh_frame,"a",@progbits
+.LSTARTFRAME:
+        .long .LENDCIE-.LSTARTCIE
+.LSTARTCIE:
+        .long 0                 /* CIE ID */
+        .byte 1                 /* Version number */
+        .string "zR"            /* NUL-terminated augmentation string */
+        .uleb128 1              /* Code alignment factor */
+        .sleb128 -4             /* Data alignment factor */
+        .byte 8                 /* Return address register column */
+        .uleb128 1              /* Augmentation value length */
+        .byte 0x1b              /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
+        .byte 0x0c              /* DW_CFA_def_cfa */
+        .uleb128 4
+        .uleb128 4
+        .byte 0x88              /* DW_CFA_offset, column 0x8 */
+        .uleb128 1
+        .align 4
+.LENDCIE:
+
+        .long .LENDFDE1-.LSTARTFDE1     /* Length FDE */
+.LSTARTFDE1:
+        .long .LSTARTFDE1-.LSTARTFRAME  /* CIE pointer */
+        .long .LSTART_vsyscall-.        /* PC-relative start address */
+        .long .LEND_vsyscall-.LSTART_vsyscall
+        .uleb128 0                      /* Augmentation length */
+        /* What follows are the instructions for the table generation.
+           We have to record all changes of the stack pointer.  */
+        .byte 0x40 + .Lpush_ebp-.LSTART_vsyscall /* DW_CFA_advance_loc */
+        .byte 0x0e              /* DW_CFA_def_cfa_offset */
+        .uleb128 8
+        .byte 0x85, 0x02        /* DW_CFA_offset %ebp -8 */
+        .byte 0x40 + .Lpop_ebp-.Lpush_ebp /* DW_CFA_advance_loc */
+        .byte 0xc5              /* DW_CFA_restore %ebp */
+        .byte 0x0e              /* DW_CFA_def_cfa_offset */
+        .uleb128 4
+        .align 4
+.LENDFDE1:
+
+/*
+ * Get the common code for the sigreturn entry points.
+ */
+#define SYSCALL_ENTER_KERNEL    syscall
+#include "sigreturn.S"