Make page tables split-safe.

In order to minimize the likelihood of exit during page table
modifications, make the full set of page table functions split-safe.
This is not strictly necessary (and you may still incur splits due to
allocations from the allocator pool) but should make retries a very rare
occurance.

PiperOrigin-RevId: 200146688
Change-Id: I8fa36aa16b807beda2f0b057be60038258e8d597

1 files changed, 72 insertions, 0 deletions

diff --git a/pkg/sentry/platform/ring0/pagetables/BUILD b/pkg/sentry/platform/ring0/pagetables/BUILD
index 08b73e87d..023e298a0 100644
--- a/pkg/sentry/platform/ring0/pagetables/BUILD
+++ b/pkg/sentry/platform/ring0/pagetables/BUILD
@@ -1,6 +1,73 @@
 package(licenses = ["notice"])  # Apache 2.0
 
 load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("//tools/go_generics:defs.bzl", "go_template", "go_template_instance")
+
+go_template(
+    name = "generic_walker",
+    srcs = [
+        "walker_amd64.go",
+    ],
+    opt_types = [
+        "Visitor",
+    ],
+    visibility = [":__pkg__"],
+)
+
+go_template_instance(
+    name = "walker_map",
+    out = "walker_map.go",
+    package = "pagetables",
+    prefix = "map",
+    template = ":generic_walker",
+    types = {
+        "Visitor": "mapVisitor",
+    },
+)
+
+go_template_instance(
+    name = "walker_unmap",
+    out = "walker_unmap.go",
+    package = "pagetables",
+    prefix = "unmap",
+    template = ":generic_walker",
+    types = {
+        "Visitor": "unmapVisitor",
+    },
+)
+
+go_template_instance(
+    name = "walker_lookup",
+    out = "walker_lookup.go",
+    package = "pagetables",
+    prefix = "lookup",
+    template = ":generic_walker",
+    types = {
+        "Visitor": "lookupVisitor",
+    },
+)
+
+go_template_instance(
+    name = "walker_empty",
+    out = "walker_empty.go",
+    package = "pagetables",
+    prefix = "empty",
+    template = ":generic_walker",
+    types = {
+        "Visitor": "emptyVisitor",
+    },
+)
+
+go_template_instance(
+    name = "walker_check",
+    out = "walker_check.go",
+    package = "pagetables",
+    prefix = "check",
+    template = ":generic_walker",
+    types = {
+        "Visitor": "checkVisitor",
+    },
+)
 
 go_library(
     name = "pagetables",
@@ -11,6 +78,10 @@ go_library(
         "pagetables_amd64.go",
         "pagetables_x86.go",
         "pcids_x86.go",
+        "walker_empty.go",
+        "walker_lookup.go",
+        "walker_map.go",
+        "walker_unmap.go",
     ],
     importpath = "gvisor.googlesource.com/gvisor/pkg/sentry/platform/ring0/pagetables",
     visibility = [
@@ -26,6 +97,7 @@ go_test(
     srcs = [
         "pagetables_amd64_test.go",
         "pagetables_test.go",
+        "walker_check.go",
     ],
     embed = [":pagetables"],
     deps = ["//pkg/sentry/usermem"],