[Minios-devel] [UNIKRAFT PATCH] lib/ukdebug: Print bottom of stack instead of thread name

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

The option of printing the thread name of the one
issueing a uk_printd() call did not work all the
time and causes the system to access invalid memory
addresses for retrieving the thread name string. The
reason is that we currently do not have a fast and
efficient way to differentiate if a stack was created
by libuksched or not (e.g., boot stacks, interrupt stacks).

This patch changes this option to print the bottom
address of the current stack instead. This way, the user
can still distinguish different threads or stack types
by their stack address and we remove any dependency to
other libraries or system configuration.

Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
---
 lib/ukdebug/Config.uk |  8 ++++----
 lib/ukdebug/print.c   | 30 ++++++++++--------------------
 2 files changed, 14 insertions(+), 24 deletions(-)

diff --git a/lib/ukdebug/Config.uk b/lib/ukdebug/Config.uk
index 2a1ea7e..dcaeb3a 100644
--- a/lib/ukdebug/Config.uk
+++ b/lib/ukdebug/Config.uk
@@ -44,10 +44,10 @@ config LIBUKDEBUG_PRINTD_TIME
        default y
        depends on LIBUKDEBUG_PRINTD
 
-config LIBUKDEBUG_PRINTD_THREAD
-       bool "Show name of thread in debug messages"
-       default y
-       depends on LIBUKDEBUG_PRINTD && LIBUKSCHED
+config LIBUKDEBUG_PRINTD_STACK
+       bool "Print bottom address of stack in debug messages"
+       default n
+       depends on LIBUKDEBUG_PRINTD
 
 choice
        prompt "Message redirection"
diff --git a/lib/ukdebug/print.c b/lib/ukdebug/print.c
index 9673dc9..42dca4a 100644
--- a/lib/ukdebug/print.c
+++ b/lib/ukdebug/print.c
@@ -44,9 +44,6 @@
 #include <uk/plat/console.h>
 #include <uk/plat/time.h>
 #include <uk/print.h>
-#if LIBUKSCHED
-#include <uk/thread.h>
-#endif
 #include <uk/errptr.h>
 #include <uk/arch/lcpu.h>
 
@@ -96,24 +93,17 @@ static void _printd_timestamp(void)
 }
 #endif
 
-#if LIBUKDEBUG_PRINTD_THREAD
-static void _printd_thread(void)
+#if LIBUKDEBUG_PRINTD_STACK
+static void _printd_stack(void)
 {
-       struct uk_thread *thread;
+       unsigned long stackb;
+       char buf[BUFLEN];
+       int len;
 
-       thread = uk_thread_current();
-       if (!PTRISERR(thread) && thread->name) {
-               _ukplat_coutd("<", 1);
-               _ukplat_coutd((char *)thread->name,
-                               strlen(thread->name));
-               _ukplat_coutd("> ", 2);
-       } else {
-               char buf[BUFLEN];
-               int len;
+       stackb = (ukarch_read_sp() & ~(__STACK_SIZE - 1)) + __STACK_SIZE;
 
-               len = snprintf(buf, BUFLEN, "<%p> ", thread);
-               _ukplat_coutd((char *)buf, len);
-       }
+       len = snprintf(buf, BUFLEN, "<%p> ", (void *) stackb);
+       _ukplat_coutd((char *)buf, len);
 }
 #endif
 
@@ -175,8 +165,8 @@ static inline void _vprintd(int lvl, const char *libname, 
const char *srcname,
                        _printd_timestamp();
 #endif
                        _ukplat_coutd(DECONST(char *, msghdr), 6);
-#if LIBUKDEBUG_PRINTD_THREAD
-                       _printd_thread();
+#if LIBUKDEBUG_PRINTD_STACK
+                       _printd_stack();
 #endif
                        if (libname) {
                                _ukplat_coutd("[", 1);
-- 
2.7.4


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