From d479afa0372598d1417fbd4ba7cd2459df1aed4a Mon Sep 17 00:00:00 2001
From: Kelvin Zhang <zhangkelvin@google.com>
Date: Fri, 18 Aug 2023 13:13:54 -0700
Subject: [PATCH] Load kernel modules from /lib/modules/`uname -r`_$(page_size)
 if present

To support booting from both 4k/16k kernels, init need to tell which
kernel we are currently booting and load the right modules. To resolve
this issue, we store 16K modules into /lib/modules/`uname -r`_16k
directory.

Test: th
Bug: 293313353
Change-Id: I4a8296384537a71e16cd20e76e6c5dfb9074f574
---
 init/first_stage_init.cpp | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/init/first_stage_init.cpp b/init/first_stage_init.cpp
index 88300cb29..3239eb7ca 100644
--- a/init/first_stage_init.cpp
+++ b/init/first_stage_init.cpp
@@ -35,6 +35,7 @@
 #include <android-base/chrono_utils.h>
 #include <android-base/file.h>
 #include <android-base/logging.h>
+#include <android-base/stringprintf.h>
 #include <modprobe/modprobe.h>
 #include <private/android_filesystem_config.h>
 
@@ -153,6 +154,15 @@ void PrepareSwitchRoot() {
         Copy(snapuserd, dst);
     }
 }
+
+std::string GetPageSizeSuffix() {
+    static const size_t page_size = sysconf(_SC_PAGE_SIZE);
+    if (page_size <= 4096) {
+        return "";
+    }
+    return android::base::StringPrintf("_%zuk", page_size / 1024);
+}
+
 }  // namespace
 
 std::string GetModuleLoadList(BootMode boot_mode, const std::string& dir_path) {
@@ -201,10 +211,18 @@ bool LoadKernelModules(BootMode boot_mode, bool want_console, bool want_parallel
     }
     dirent* entry = nullptr;
     std::vector<std::string> module_dirs;
+    const std::string release_specific_module_dir = uts.release + GetPageSizeSuffix();
     while ((entry = readdir(base_dir.get()))) {
         if (entry->d_type != DT_DIR) {
             continue;
         }
+        if (entry->d_name == release_specific_module_dir) {
+            LOG(INFO) << "Release specific kernel module dir " << release_specific_module_dir
+                      << " found, loading modules from here with no fallbacks.";
+            module_dirs.clear();
+            module_dirs.emplace_back(entry->d_name);
+            break;
+        }
         int dir_major = 0, dir_minor = 0;
         if (sscanf(entry->d_name, "%d.%d", &dir_major, &dir_minor) != 2 || dir_major != major ||
             dir_minor != minor) {
@@ -228,6 +246,7 @@ bool LoadKernelModules(BootMode boot_mode, bool want_console, bool want_parallel
         bool retval = m.LoadListedModules(!want_console);
         modules_loaded = m.GetModuleCount();
         if (modules_loaded > 0) {
+            LOG(INFO) << "Loaded " << modules_loaded << " modules from " << dir_path;
             return retval;
         }
     }
@@ -237,6 +256,7 @@ bool LoadKernelModules(BootMode boot_mode, bool want_console, bool want_parallel
                                   : m.LoadListedModules(!want_console);
     modules_loaded = m.GetModuleCount();
     if (modules_loaded > 0) {
+        LOG(INFO) << "Loaded " << modules_loaded << " modules from " << MODULE_BASE_DIR;
         return retval;
     }
     return true;