From 95ac23754bb20c6998d8b02dd4c7eb80e9ff8e9f Mon Sep 17 00:00:00 2001
From: Benjamin Levy <benjamin.levy@ll.mit.edu>
Date: Tue, 2 Jul 2024 14:56:03 -0400
Subject: [PATCH] Page-in strings with macro

---
 nvram.c   | 10 +++++-----
 strings.c | 11 +++++------
 strings.h |  4 +++-
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/nvram.c b/nvram.c
index d9fdddd..31af7f8 100644
--- a/nvram.c
+++ b/nvram.c
@@ -126,7 +126,7 @@ int nvram_clear(void) {
         // Clear is really a bunch of unsets
         rv = igloo_hypercall2(110, (unsigned long)path, strlen(path));
         while (rv == 1) {
-            igloo_page_in_str(path);
+            PAGE_IN(path);
             rv = igloo_hypercall2(110, (unsigned long)path, strlen(path));
         }
     }
@@ -285,7 +285,7 @@ int nvram_get_buf(const char *key, char *buf, size_t sz) {
 
         rv = igloo_hypercall2(107, (unsigned long)path, strlen(path));
         while (rv == 1) {
-            igloo_page_in_str(path);
+            PAGE_IN(path);
             rv = igloo_hypercall2(107, (unsigned long)path, strlen(path));
         }
 
@@ -308,7 +308,7 @@ int nvram_get_buf(const char *key, char *buf, size_t sz) {
         // success
         rv = igloo_hypercall2(108, (unsigned long)path, strlen(path));
         while (rv == 1) {
-            igloo_page_in_str(path);
+            PAGE_IN(path);
             rv = igloo_hypercall2(108, (unsigned long)path, strlen(path));
         }
     }
@@ -469,7 +469,7 @@ int nvram_set(const char *key, const char *val) {
 
     rv = igloo_hypercall2(109, (unsigned long)path, (unsigned long)val);
     while (rv == 1) {
-        igloo_page_in_str(path);
+        PAGE_IN(path);
         rv = igloo_hypercall2(109, (unsigned long)path, (unsigned long)val);
     }
 
@@ -544,7 +544,7 @@ int nvram_unset(const char *key) {
 
     rv = igloo_hypercall2(110, (unsigned long)path, strlen(path));
     while (rv == 1) {
-        igloo_page_in_str(path);
+        PAGE_IN(path);
         rv = igloo_hypercall2(110, (unsigned long)path, strlen(path));
     }
 
diff --git a/strings.c b/strings.c
index 9a7101f..c210215 100644
--- a/strings.c
+++ b/strings.c
@@ -14,9 +14,8 @@ typedef struct {
     const char* value;
 } match;
 
-void igloo_page_in_str(const char *s) {
-    volatile const char *p = s;
-    while (*p++);
+void igloo_page_in_str(volatile const char *s) {
+    while (*s++);
 }
 
 void log_match(match m) {
@@ -35,7 +34,7 @@ void log_match(match m) {
 
     int rv = igloo_hypercall2(cmd, (unsigned long)m.value, minimal_strlen(m.value));
     while (rv == 1) {
-        igloo_page_in_str(m.value);
+        PAGE_IN(m.value);
         rv = igloo_hypercall2(cmd, (unsigned long)m.value, minimal_strlen(m.value));
     }
 }
@@ -126,8 +125,8 @@ char *strstr(const char *haystack, const char *needle) {
     // Hypercall returns -1 on read fail. If no hypercall is available we'd get a different reval
     // so we wouldn't infinite loop. Hopefully.
     while (rv == 1) {
-        igloo_page_in_str(haystack);
-        igloo_page_in_str(needle);
+        PAGE_IN(haystack);
+        PAGE_IN(needle);
         rv = igloo_hypercall2(104, (unsigned long)haystack, (unsigned long)needle);
     }
 
diff --git a/strings.h b/strings.h
index 5f6a4af..9f14b8a 100644
--- a/strings.h
+++ b/strings.h
@@ -4,10 +4,12 @@
 #include "hypercall.h"
 #include <stddef.h>
 
+#define PAGE_IN(s) igloo_page_in_str((volatile const char *)(s))
+
 #define TARGET_VALUE "DYNVALDYNVALDYNVAL"
 extern char **environ;
 
-void igloo_page_in_str(const char *s);
+void igloo_page_in_str(volatile const char *s);
 size_t minimal_strlen(const char *s);
 int minimal_strncmp(short do_log, size_t n, const char *s1, const char *s2);
 int minimal_strcmp(const char *s1, const char *s2, short do_log);