tools/ocaml: Introduce xenctrl ABI build-time checks

c/s f089fddd941 broke the Ocaml ABI by renumering
XEN_SYSCTL_PHYSCAP_directio without adjusting the Ocaml
physinfo_cap_flag enumeration.

Add build machinery which will check the ABI correspondence.

This will result in a compile time failure whenever constants get
renumbered/added without a compatible adjustment to the Ocaml ABI.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <Andrew.Cooper3@citrix.com>

diff --git a/.gitignore b/.gitignore
index 3c947ac9487c8c5fe2ecc3159b320996da1d28b5..3ada0c4f0bb8631221ad43c06c2f9a6308783726 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -392,6 +392,7 @@ tools/ocaml/libs/xentoollog/_xtl_levels.*
 tools/ocaml/libs/xentoollog/xentoollog.ml
 tools/ocaml/libs/xentoollog/xentoollog.mli
 tools/ocaml/libs/xs/paths.ml
+tools/ocaml/libs/xc/xenctrl_abi_check.h
 tools/ocaml/xenstored/_paths.h
 tools/ocaml/xenstored/oxenstored
 tools/ocaml/xenstored/oxenstored.conf

diff --git a/tools/ocaml/libs/xc/Makefile b/tools/ocaml/libs/xc/Makefile
index d24b0144d020060de16f45db7ab9b782e412fe40..b6da4fdbaf845328660cbbe8eb126bdb5e8ae5a5 100644 (file)
--- a/tools/ocaml/libs/xc/Makefile
+++ b/tools/ocaml/libs/xc/Makefile
@@ -31,4 +31,11 @@ install: $(LIBS) META
 uninstall:
        $(OCAMLFIND) remove -destdir $(OCAMLDESTDIR) xenctrl
 
+xenctrl_stubs.o: xenctrl_abi_check.h
+
+xenctrl_abi_check.h: abi-check xenctrl_stubs.c xenctrl.ml
+       $(PERL) -w $^ >$@.tmp && mv -f $@.tmp $@
+
+GENERATED_FILES += xenctrl_abi_check.h
+
 include $(TOPLEVEL)/Makefile.rules

diff --git a/tools/ocaml/libs/xc/abi-check b/tools/ocaml/libs/xc/abi-check
new file mode 100755 (executable)
index 0000000..c987cd8
--- /dev/null
+++ b/tools/ocaml/libs/xc/abi-check
@@ -0,0 +1,84 @@
+#!/usr/bin/perl -w
+
+use strict;
+use Data::Dumper;
+
+our %enums;
+
+@ARGV == 2 or die;
+our ($c, $o) = @ARGV;
+
+open STDIN, "<", $c or die $!;
+
+our $cline = -1;
+our $ei;
+
+while (<>) {
+    if ($cline == -1) {
+        if (m/c_bitmap_to_ocaml_list/) {
+            $cline = 0;
+            $ei = { };
+        }
+    } else {
+        $cline++;
+        m{^\s+/\* \s+ ! \s+ (.*?) \s* \*/\s*$}x or die "$cline $_ ?";
+        my @vals = split /\s+/, $1;
+        if ($cline == 1 && !@vals) {
+            $cline = -1;
+        } elsif ($cline == 1 && @vals == 3) {
+            $ei->{$_} = shift @vals foreach qw(OType OPrefix Mangle);
+        } elsif ($cline == 2 && @vals == 3) {
+            $ei->{$_} = shift @vals foreach qw(CPrefix CFinal CFinalHow);
+            die if $enums{ $ei->{OType} };
+            $enums{ $ei->{OType} } = $ei;
+            $cline = -1;
+        } else {
+            die "$_ ?";
+        }
+    }
+}
+
+sub expect ($$) {
+    printf "BUILD_BUG_ON( %-30s != %-10s );\n", @_ or die $!;
+}
+
+open STDIN, "<", $o or die $!;
+my $cval;
+$ei = undef;
+my $bitnum = 0;
+while (<>) {
+    if (!$ei) {
+        if (m{^type \s+ (\w+) \s* \= \s* $/}x && $enums{$1}) {
+            $ei = $enums{$1};
+            $cval = '';
+            $bitnum = 0;
+        }
+    } else {
+        if (m{^\s+ \| \s* $ei->{OPrefix} (\w+) \s*$}x) {
+            $cval = $1;
+            if ($ei->{Mangle} eq 'lc') {
+                $cval = lc $cval;
+            } elsif ($ei->{Mangle} eq 'none') {
+            } else {
+                die;
+            }
+            $cval = $ei->{CPrefix}.$cval;
+            expect($cval, "(1u << $bitnum)");
+            $bitnum++;
+        } elsif (m/^\w|\{/) {
+            if ($ei->{CFinalHow} eq 'max') {
+                expect($ei->{CFinal}, "(1u << ".($bitnum-1).")");
+            } elsif ($ei->{CFinalHow} eq 'all') {
+                expect($ei->{CFinal}, "(1u << $bitnum)-1u");
+            } else {
+                die Dumper($ei)." ?";
+            }
+            $ei = undef;
+        } elsif (!m{\S}) {
+        } else {
+            die "$_ ?";
+        }
+    }
+}
+
+close STDOUT or die $!;

diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index 2e1b29ce33f1271376a5ec6d3d5f4afb26509bea..352a6bd2d6e279e2da5fbfea6f6208c0e7c0ee0e 100644 (file)
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -32,6 +32,7 @@
 
 #define XC_WANT_COMPAT_MAP_FOREIGN_API
 #include <xenctrl.h>
+#include <xen-tools/libs.h>
 
 #include "mmap_stubs.h"
 
@@ -119,6 +120,39 @@ static void domain_handle_of_uuid_string(xen_domain_handle_t h,
 #undef X
 }
 
+/*
+ * Various fields which are a bitmap in the C ABI are converted to lists of
+ * integers in the Ocaml ABI for more idiomatic handling.
+ */
+static value c_bitmap_to_ocaml_list
+             /* ! */
+             /*
+             * All calls to this function must be in a form suitable
+             * for xenctrl_abi_check.  The parsing there is ad-hoc.
+             */
+             (unsigned int bitmap)
+{
+       CAMLparam0();
+       CAMLlocal2(list, tmp);
+
+#include "xenctrl_abi_check.h"
+
+       list = tmp = Val_emptylist;
+
+       for ( unsigned int i = 0; bitmap; i++, bitmap >>= 1 )
+       {
+               if ( !(bitmap & 1) )
+                       continue;
+
+               tmp = caml_alloc_small(2, Tag_cons);
+               Field(tmp, 0) = Val_int(i);
+               Field(tmp, 1) = list;
+               list = tmp;
+       }
+
+       CAMLreturn(list);
+}
+
 CAMLprim value stub_xc_domain_create(value xch, value config)
 {
        CAMLparam2(xch, config);
@@ -315,16 +349,13 @@ static value alloc_domaininfo(xc_domaininfo_t * info)
        Store_field(result, 15, tmp);
 
 #if defined(__i386__) || defined(__x86_64__)
-       /* emulation_flags: x86_arch_emulation_flags list; */
-       tmp = emul_list = Val_emptylist;
-       for (i = 0; i < 10; i++) {
-               if ((info->arch_config.emulation_flags >> i) & 1) {
-                       tmp = caml_alloc_small(2, Tag_cons);
-                       Field(tmp, 0) = Val_int(i);
-                       Field(tmp, 1) = emul_list;
-                       emul_list = tmp;
-               }
-       }
+       /*
+        * emulation_flags: x86_arch_emulation_flags list;
+        */
+       emul_list = c_bitmap_to_ocaml_list
+               /* ! x86_arch_emulation_flags X86_EMU_ none */
+               /* ! XEN_X86_EMU_ XEN_X86_EMU_ALL all */
+               (info->arch_config.emulation_flags);
 
        /* xen_x86_arch_domainconfig */
        x86_arch_config = caml_alloc_tuple(1);
@@ -635,7 +666,7 @@ CAMLprim value stub_xc_send_debug_keys(value xch, value keys)
 CAMLprim value stub_xc_physinfo(value xch)
 {
        CAMLparam1(xch);
-       CAMLlocal3(physinfo, cap_list, tmp);
+       CAMLlocal2(physinfo, cap_list);
        xc_physinfo_t c_physinfo;
        int r;
 
@@ -646,15 +677,13 @@ CAMLprim value stub_xc_physinfo(value xch)
        if (r)
                failwith_xc(_H(xch));
 
-       tmp = cap_list = Val_emptylist;
-       for (r = 0; r < 2; r++) {
-               if ((c_physinfo.capabilities >> r) & 1) {
-                       tmp = caml_alloc_small(2, Tag_cons);
-                       Field(tmp, 0) = Val_int(r);
-                       Field(tmp, 1) = cap_list;
-                       cap_list = tmp;
-               }
-       }
+       /*
+        * capabilities: physinfo_cap_flag list;
+        */
+       cap_list = c_bitmap_to_ocaml_list
+               /* ! physinfo_cap_flag CAP_ lc */
+               /* ! XEN_SYSCTL_PHYSCAP_ XEN_SYSCTL_PHYSCAP_MAX max */
+               (c_physinfo.capabilities);
 
        physinfo = caml_alloc_tuple(10);
        Store_field(physinfo, 0, Val_int(c_physinfo.threads_per_core));

diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index 36b3f8c42914c1723bbbc2b8313e2e7e5f0f0315..5401f9c2fea8991f425b73d4d1f32c292d6e1756 100644 (file)
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -90,6 +90,10 @@ struct xen_sysctl_tbuf_op {
  /* The platform supports direct access to I/O devices with IOMMU. */
 #define _XEN_SYSCTL_PHYSCAP_directio     2
 #define XEN_SYSCTL_PHYSCAP_directio  (1u<<_XEN_SYSCTL_PHYSCAP_directio)
+
+/* Max XEN_SYSCTL_PHYSCAP_* constant.  Used for ABI checking. */
+#define XEN_SYSCTL_PHYSCAP_MAX XEN_SYSCTL_PHYSCAP_directio
+
 struct xen_sysctl_physinfo {
     uint32_t threads_per_core;
     uint32_t cores_per_socket;