From dbac204e8b4674f7ca8793eb56f0243808b11e9e Mon Sep 17 00:00:00 2001
From: Hridya Valsaraju <hridya@google.com>
Date: Fri, 16 Aug 2019 14:00:04 -0700
Subject: [PATCH] Do not access ext_csd register in debugfs from storaged

Starting from Android R, platform code cannot access files in debugfs
since it does not guarantee ABI stability. This CL removes the code in
storaged that accesses the EMMC's ext_csd register from debugfs as a
backup if it is unable to obtain the information from Health HAL.

Test: build and boot.
Bug: 134669095
Change-Id: I3bfeb3963de5fb5e6bb3eaa9df43baacad164816
---
 storaged/storaged_info.cpp | 58 ++------------------------------------
 1 file changed, 3 insertions(+), 55 deletions(-)

diff --git a/storaged/storaged_info.cpp b/storaged/storaged_info.cpp
index ca2421b41..6668cf38b 100644
--- a/storaged/storaged_info.cpp
+++ b/storaged/storaged_info.cpp
@@ -41,7 +41,6 @@ using android::hardware::health::V2_0::Result;
 using android::hardware::health::V2_0::StorageInfo;
 
 const string emmc_info_t::emmc_sysfs = "/sys/bus/mmc/devices/mmc0:0001/";
-const string emmc_info_t::emmc_debugfs = "/d/mmc0/mmc0:0001/ext_csd";
 const char* emmc_info_t::emmc_ver_str[9] = {
     "4.0", "4.1", "4.2", "4.3", "Obsolete", "4.41", "4.5", "5.0", "5.1"
 };
@@ -62,10 +61,8 @@ storage_info_t* storage_info_t::get_storage_info(const sp<IHealth>& healthServic
     if (healthService != nullptr) {
         return new health_storage_info_t(healthService);
     }
-    if (FileExists(emmc_info_t::emmc_sysfs) ||
-        FileExists(emmc_info_t::emmc_debugfs)) {
-        return new emmc_info_t;
-    }
+    if (FileExists(emmc_info_t::emmc_sysfs)) return new emmc_info_t;
+
     if (FileExists(ufs_info_t::health_file)) {
         return new ufs_info_t;
     }
@@ -241,8 +238,7 @@ uint32_t storage_info_t::get_recent_perf() {
 
 void emmc_info_t::report()
 {
-    if (!report_sysfs() && !report_debugfs())
-        return;
+    if (!report_sysfs()) return;
 
     publish();
 }
@@ -284,54 +280,6 @@ bool emmc_info_t::report_sysfs()
     return true;
 }
 
-namespace {
-
-const size_t EXT_CSD_FILE_MIN_SIZE = 1024;
-/* 2 characters in string for each byte */
-const size_t EXT_CSD_REV_IDX = 192 * 2;
-const size_t EXT_PRE_EOL_INFO_IDX = 267 * 2;
-const size_t EXT_DEVICE_LIFE_TIME_EST_A_IDX = 268 * 2;
-const size_t EXT_DEVICE_LIFE_TIME_EST_B_IDX = 269 * 2;
-
-} // namespace
-
-bool emmc_info_t::report_debugfs()
-{
-    string buffer;
-    uint16_t rev = 0;
-
-    if (!ReadFileToString(emmc_debugfs, &buffer) ||
-        buffer.length() < (size_t)EXT_CSD_FILE_MIN_SIZE) {
-        return false;
-    }
-
-    string str = buffer.substr(EXT_CSD_REV_IDX, 2);
-    if (!ParseUint(str, &rev) ||
-        rev < 7 || rev > ARRAY_SIZE(emmc_ver_str)) {
-        return false;
-    }
-
-    version = "emmc ";
-    version += emmc_ver_str[rev];
-
-    str = buffer.substr(EXT_PRE_EOL_INFO_IDX, 2);
-    if (!ParseUint(str, &eol)) {
-        return false;
-    }
-
-    str = buffer.substr(EXT_DEVICE_LIFE_TIME_EST_A_IDX, 2);
-    if (!ParseUint(str, &lifetime_a)) {
-        return false;
-    }
-
-    str = buffer.substr(EXT_DEVICE_LIFE_TIME_EST_B_IDX, 2);
-    if (!ParseUint(str, &lifetime_b)) {
-        return false;
-    }
-
-    return true;
-}
-
 void ufs_info_t::report()
 {
     string buffer;