From 29c5d381cd4d36b5e3ce140193729a5a4b97c31e Mon Sep 17 00:00:00 2001
From: Viktor Malik <viktor.malik@gmail.com>
Date: Mon, 6 Mar 2023 11:41:27 +0100
Subject: [PATCH 2/2] arm64: define the KASAN_SHADOW_SCALE_SHIFT macro

arm64 defines this macro from Makefile instead of defining it in a
header file as is the case for other architectures. Since we're not
running make, we need to define the macro manually via CFLAGS.

The value definition is taken from kernel's arch/arm64/Makefile and it
depends on the running kernel configuration.

This fixes the runqlat.bt tcpdrop.bt, and undump.bt tools on
aarch64+debug kernel which previously failed with:

    # /usr/share/bpftrace/tools/runqlat.bt
    [...]/source/arch/arm64/include/asm/memory.h:300:9: error: use of undeclared identifier 'KASAN_SHADOW_SCALE_SHIFT'
    [...]
---
 src/main.cpp  |  3 ++-
 src/utils.cpp | 23 ++++++++++++++++++-----
 src/utils.h   |  3 ++-
 3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index b76d1bb3..593c71be 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -370,7 +370,8 @@ static std::optional<struct timespec> get_boottime()
     kobj = std::get<1>(kdirs);
 
     if (ksrc != "")
-      extra_flags = get_kernel_cflags(utsname.machine, ksrc, kobj);
+      extra_flags = get_kernel_cflags(
+          utsname.machine, ksrc, kobj, bpftrace.kconfig);
   }
   extra_flags.push_back("-include");
   extra_flags.push_back(CLANG_WORKAROUNDS_H);
diff --git a/src/utils.cpp b/src/utils.cpp
index 54c8f054..c8fd7da1 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -227,7 +227,6 @@ KConfig::KConfig()
   }
 }
 
-
 bool get_uint64_env_var(const std::string &str, uint64_t &dest)
 {
   if (const char* env_p = std::getenv(str.c_str()))
@@ -364,10 +363,10 @@ std::vector<int> get_possible_cpus()
   return read_cpu_range("/sys/devices/system/cpu/possible");
 }
 
-std::vector<std::string> get_kernel_cflags(
-    const char* uname_machine,
-    const std::string& ksrc,
-    const std::string& kobj)
+std::vector<std::string> get_kernel_cflags(const char *uname_machine,
+                                           const std::string &ksrc,
+                                           const std::string &kobj,
+                                           const KConfig &kconfig)
 {
   std::vector<std::string> cflags;
   std::string arch = uname_machine;
@@ -433,6 +432,20 @@ std::vector<std::string> get_kernel_cflags(
     cflags.push_back("-D__LINUX_ARM_ARCH__=7");
   }
 
+  if (arch == "arm64")
+  {
+    // arm64 defines KASAN_SHADOW_SCALE_SHIFT in a Makefile instead of defining
+    // it in a header file. Since we're not executing make, we need to set the
+    // value manually (values are taken from arch/arm64/Makefile).
+    if (kconfig.has_value("CONFIG_KASAN", "y"))
+    {
+      if (kconfig.has_value("CONFIG_KASAN_SW_TAGS", "y"))
+        cflags.push_back("-DKASAN_SHADOW_SCALE_SHIFT=4");
+      else
+        cflags.push_back("-DKASAN_SHADOW_SCALE_SHIFT=3");
+    }
+  }
+
   return cflags;
 }
 
diff --git a/src/utils.h b/src/utils.h
index a76aa161..d4eeac3d 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -178,7 +178,8 @@ std::tuple<std::string, std::string> get_kernel_dirs(
     bool unpack_kheaders);
 std::vector<std::string> get_kernel_cflags(const char *uname_machine,
                                            const std::string &ksrc,
-                                           const std::string &kobj);
+                                           const std::string &kobj,
+                                           const KConfig &kconfig);
 std::string get_cgroup_path_in_hierarchy(uint64_t cgroupid,
                                          std::string base_path);
 std::vector<std::pair<std::string, std::string>> get_cgroup_hierarchy_roots();
-- 
2.39.2