From 5d397582acb4a4ec2b7bb2aa08ec7c9dcb8d701d Mon Sep 17 00:00:00 2001
From: Kalesh Singh <kaleshsingh@google.com>
Date: Fri, 4 Aug 2023 16:59:12 -0700
Subject: [PATCH] lmkd: Remove uses of hardcoded 4k PAGE_SIZE macro

Use getpagesize() to query the real page size instead.

Bug: 294618124
Test: m
Change-Id: If9046f36412a54ba08b94cf3b43cd7bf9c1f26b5
---
 include/lmkd.h |  5 +++++
 lmkd.cpp       | 20 +++++++++-----------
 statslog.cpp   |  7 ++++---
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/include/lmkd.h b/include/lmkd.h
index d710d50..b610e77 100644
--- a/include/lmkd.h
+++ b/include/lmkd.h
@@ -50,6 +50,11 @@ enum lmk_cmd {
  */
 #define CTRL_PACKET_MAX_SIZE (sizeof(int) * (MAX_TARGETS * 2 + 1))
 
+/*
+ * Max number of characters in line.
+ */
+#define LINE_MAX 128
+
 /* LMKD packet - first int is lmk_cmd followed by payload */
 typedef int LMKD_CTRL_PACKET[CTRL_PACKET_MAX_SIZE / sizeof(int)];
 
diff --git a/lmkd.cpp b/lmkd.cpp
index 02fb553..9a966a3 100644
--- a/lmkd.cpp
+++ b/lmkd.cpp
@@ -91,7 +91,6 @@ static inline void trace_kill_end() {}
 #define PROC_STATUS_TGID_FIELD "Tgid:"
 #define PROC_STATUS_RSS_FIELD "VmRSS:"
 #define PROC_STATUS_SWAP_FIELD "VmSwap:"
-#define LINE_MAX 128
 
 #define PERCEPTIBLE_APP_ADJ 200
 
@@ -545,8 +544,8 @@ static uint16_t killcnt[MAX_DISTINCT_OOM_ADJ];
 static int killcnt_free_idx = 0;
 static uint32_t killcnt_total = 0;
 
-/* PAGE_SIZE / 1024 */
-static long page_k;
+static int pagesize;
+static long page_k; /* page size in kB */
 
 static bool update_props();
 static bool init_monitors();
@@ -622,7 +621,7 @@ static ssize_t read_all(int fd, char *buf, size_t max_len)
  */
 static char *reread_file(struct reread_data *data) {
     /* start with page-size buffer and increase if needed */
-    static ssize_t buf_size = PAGE_SIZE;
+    static ssize_t buf_size = pagesize;
     static char *new_buf, *buf = NULL;
     ssize_t size;
 
@@ -843,7 +842,7 @@ static void poll_kernel(int poll_fd) {
         if (fields_read == 10 && group_leader_pid == pid) {
             ctrl_data_write_lmk_kill_occurred((pid_t)pid, (uid_t)uid);
             mem_st.process_start_time_ns = starttime * (NS_PER_SEC / sysconf(_SC_CLK_TCK));
-            mem_st.rss_in_bytes = rss_in_pages * PAGE_SIZE;
+            mem_st.rss_in_bytes = rss_in_pages * pagesize;
 
             struct kill_stat kill_st = {
                 .uid = static_cast<int32_t>(uid),
@@ -1104,7 +1103,7 @@ static void cmd_procprio(LMKD_CTRL_PACKET packet, int field_count, struct ucred
     bool is_system_server;
     struct passwd *pwdrec;
     int64_t tgid;
-    char buf[PAGE_SIZE];
+    char buf[pagesize];
 
     lmkd_pack_get_procprio(packet, field_count, &params);
 
@@ -2299,7 +2298,7 @@ static int kill_one_process(struct proc* procp, int min_oom_score, struct kill_i
     int64_t tgid;
     int64_t rss_kb;
     int64_t swap_kb;
-    char buf[PAGE_SIZE];
+    char buf[pagesize];
     char desc[LINE_MAX];
 
     if (!procp->valid || !read_proc_status(pid, buf, sizeof(buf))) {
@@ -3426,10 +3425,9 @@ static int init(void) {
     int i;
     int ret;
 
-    page_k = sysconf(_SC_PAGESIZE);
-    if (page_k == -1)
-        page_k = PAGE_SIZE;
-    page_k /= 1024;
+    // Initialize page size
+    pagesize = getpagesize();
+    page_k = pagesize / 1024;
 
     epollfd = epoll_create(MAX_EPOLL_EVENTS);
     if (epollfd == -1) {
diff --git a/statslog.cpp b/statslog.cpp
index 6e6cb42..fbb8867 100644
--- a/statslog.cpp
+++ b/statslog.cpp
@@ -32,6 +32,7 @@
 
 #include <string>
 
+#include <lmkd.h>
 #include <processgroup/processgroup.h>
 
 #ifdef LMKD_LOG_STATS
@@ -67,7 +68,7 @@ static struct proc* pid_lookup(int pid) {
     return procp;
 }
 
-static void memory_stat_parse_line(char* line, struct memory_stat* mem_st) {
+static void memory_stat_parse_line(const char* line, struct memory_stat* mem_st) {
     char key[MAX_TASKNAME_LEN + 1];
     int64_t value;
 
@@ -102,8 +103,8 @@ static int memory_stat_from_cgroup(struct memory_stat* mem_st, int pid, uid_t ui
         return -1;
     }
 
-    char buf[PAGE_SIZE];
-    while (fgets(buf, PAGE_SIZE, fp) != NULL) {
+    char buf[LINE_MAX];
+    while (fgets(buf, LINE_MAX, fp) != NULL) {
         memory_stat_parse_line(buf, mem_st);
     }
     fclose(fp);