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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2] tools/ocaml: Fix xenctrl ABI and introduce build-time checks
c/s f089fddd941 broke the Ocaml ABI by renumering XEN_SYSCTL_PHYSCAP_directio
without adjusting the Ocaml physinfo_cap_flag enumeration. Fix this by
inserting CAP_PV between CAP_HVM and CAP_DirectIO.
Factor out the bitmap-to-list conversion logic into a helper, to avoid an
opencoded truncation of the bitmap. To cover this, add BUILD_BUG_ON()'s at
the caller for each constant in the C-to-Ocaml conversion, and for the the
applicable max/all constant.
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@xxxxxxxxxx>
---
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Christian Lindig <christian.lindig@xxxxxxxxxx>
CC: Rob Hoes <Rob.Hoes@xxxxxxxxxx>
CC: Edwin Török <edvin.torok@xxxxxxxxxx>
This needs backporting to Xen 4.12
v2:
* Base this patch correctly.
---
tools/ocaml/libs/xc/xenctrl.ml | 1 +
tools/ocaml/libs/xc/xenctrl.mli | 5 ++-
tools/ocaml/libs/xc/xenctrl_stubs.c | 77 +++++++++++++++++++++++++++----------
xen/include/public/sysctl.h | 4 ++
4 files changed, 66 insertions(+), 21 deletions(-)
diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index 35958b94d5..cd7e95a6fa 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -99,6 +99,7 @@ type sched_control =
type physinfo_cap_flag =
| CAP_HVM
+ | CAP_PV
| CAP_DirectIO
type physinfo =
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index 6c4268d453..0bd06ed920 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -82,7 +82,10 @@ type domaininfo = {
arch_config : arch_domainconfig;
}
type sched_control = { weight : int; cap : int; }
-type physinfo_cap_flag = CAP_HVM | CAP_DirectIO
+type physinfo_cap_flag =
+ | CAP_HVM
+ | CAP_PV
+ | CAP_DirectIO
type physinfo = {
threads_per_core : int;
cores_per_socket : int;
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c
b/tools/ocaml/libs/xc/xenctrl_stubs.c
index 2e1b29ce33..ce8dbba437 100644
--- 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 +120,31 @@ 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(unsigned int bitmap)
+{
+ CAMLparam0();
+ CAMLlocal2(list, tmp);
+
+ 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 +341,25 @@ 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;
+ *
+ * These BUILD_BUG_ON()'s map the C ABI to the Ocaml ABI. If they
+ * trip, xenctrl.ml{,i} need updating to match.
+ */
+ BUILD_BUG_ON(XEN_X86_EMU_LAPIC != (1u << 0));
+ BUILD_BUG_ON(XEN_X86_EMU_HPET != (1u << 1));
+ BUILD_BUG_ON(XEN_X86_EMU_PM != (1u << 2));
+ BUILD_BUG_ON(XEN_X86_EMU_RTC != (1u << 3));
+ BUILD_BUG_ON(XEN_X86_EMU_IOAPIC != (1u << 4));
+ BUILD_BUG_ON(XEN_X86_EMU_PIC != (1u << 5));
+ BUILD_BUG_ON(XEN_X86_EMU_VGA != (1u << 6));
+ BUILD_BUG_ON(XEN_X86_EMU_IOMMU != (1u << 7));
+ BUILD_BUG_ON(XEN_X86_EMU_PIT != (1u << 8));
+ BUILD_BUG_ON(XEN_X86_EMU_USE_PIRQ != (1u << 9));
+ BUILD_BUG_ON(XEN_X86_EMU_VPCI != (1u << 10));
+ BUILD_BUG_ON(XEN_X86_EMU_ALL != 0x7ff);
+ emul_list = c_bitmap_to_ocaml_list(info->arch_config.emulation_flags);
/* xen_x86_arch_domainconfig */
x86_arch_config = caml_alloc_tuple(1);
@@ -635,7 +670,7 @@ 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 +681,17 @@ 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;
+ *
+ * These BUILD_BUG_ON()'s map the C ABI to the Ocaml ABI. If they
+ * trip, xenctrl.ml{,i} need updating to match.
+ */
+ BUILD_BUG_ON(XEN_SYSCTL_PHYSCAP_hvm != (1u << 0));
+ BUILD_BUG_ON(XEN_SYSCTL_PHYSCAP_pv != (1u << 1));
+ BUILD_BUG_ON(XEN_SYSCTL_PHYSCAP_directio != (1u << 2));
+ BUILD_BUG_ON(XEN_SYSCTL_PHYSCAP_MAX !=
XEN_SYSCTL_PHYSCAP_directio);
+ cap_list = c_bitmap_to_ocaml_list(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 36b3f8c429..5401f9c2fe 100644
--- 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;
--
2.11.0
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