From 887aa60973bddfc29ba582c8810774bba8f97497 Mon Sep 17 00:00:00 2001
From: Julian Barathieu <spectral@os-k.eu>
Date: Thu, 4 Apr 2019 18:41:39 +0200
Subject: [PATCH] Non-locking I/O for panic()

---
 kaleid/kernel/buf/bprint.c | 24 ++++++++++++++++++------
 kaleid/kernel/init/init.c  | 12 ++++++------
 kaleid/kernel/io/vga.c     |  4 +---
 kaleid/kernel/ke/panic.c   | 20 +++++++++++++++-----
 4 files changed, 40 insertions(+), 20 deletions(-)

diff --git a/kaleid/kernel/buf/bprint.c b/kaleid/kernel/buf/bprint.c
index a75ee22..1c49fd3 100644
--- a/kaleid/kernel/buf/bprint.c
+++ b/kaleid/kernel/buf/bprint.c
@@ -25,6 +25,7 @@
 #include <kernel/buf.h>
 
 extern error_t bputc(Buffer_t *buf, uchar ch);
+error_t vbprintf(Buffer_t *buf, const char *fmt, va_list ap);
 
 //
 // Prints formatted string on buf according to fmt
@@ -35,11 +36,25 @@ error_t BPrintOnBuf(Buffer_t *buf, const char *fmt, ...)
     va_list ap;
 
     va_start(ap, fmt);
-    rc = BPrintOnBufV(buf, fmt, ap);
+    ExAcquireLock(&buf->lock);
+    rc = vbprintf(buf, fmt, ap);
+    ExReleaseLock(&buf->lock);
     va_end(ap);
 
     return rc;
 }
+
+error_t BPrintOnBufV(Buffer_t *buf, const char *fmt, va_list ap)
+{
+    error_t rc;
+    
+    ExAcquireLock(&buf->lock);
+    rc = vbprintf(buf, fmt, ap);
+    ExReleaseLock(&buf->lock);
+    
+    return rc;
+}
+
 //
 // Prints 0 for octal, 0x for hexadecimal, 0b for binary
 //
@@ -81,10 +96,10 @@ static error_t bdopadding(Buffer_t *buf, size_t width, size_t len,
 #define fmtnext() do{fmt++;if(*fmt==0){rc=EINVAL;goto leave;}}while(0)
 
 //
-// Actually does BPrintOnBuf's job
+// Actually does BPrintOnBuf's job; doesn't lock anything
 // Quite a long function
 //
-error_t BPrintOnBufV(Buffer_t *buf, const char *fmt, va_list ap)
+error_t vbprintf(Buffer_t *buf, const char *fmt, va_list ap)
 {
     error_t rc = EOK;
     int tmpwidth;
@@ -120,8 +135,6 @@ error_t BPrintOnBufV(Buffer_t *buf, const char *fmt, va_list ap)
         return EBADF;
     }
 
-    ExAcquireLock(&buf->lock);
-
 //----------------------------------------------------------------------------//
 
     // We come back here after dealing with a modifier
@@ -367,7 +380,6 @@ loop:
 //----------------------------------------------------------------------------//
 
 leave:
-    ExReleaseLock(&buf->lock);
     return rc;
 }
 
diff --git a/kaleid/kernel/init/init.c b/kaleid/kernel/init/init.c
index 2e63b1a..7121469 100644
--- a/kaleid/kernel/init/init.c
+++ b/kaleid/kernel/init/init.c
@@ -147,18 +147,18 @@ noreturn void BtStartKern(multiboot_info_t *mbInfo, uint mbMagic)
     // Sanity checks and hello world
     BtInitSanity(mbMagic);
 
-    //Memory mapping
+    // Memory mapping
     MmInitMemoryMap();
 
+    // Heap initialization
     MmInitHeap();
 
-    //int i = 0;
-    //while(i < 512) { KernLog("%d\n", i++);}
-    //MmPrintMemoryMap();
-
     PsInitSched();
 
     // We're out
     PsFiniSched();
-    KeCrashSystem(); //yay
+    
+    KeStartPanic("Test Panic %d", 4);
+    
+    KeCrashSystem();
 }
diff --git a/kaleid/kernel/io/vga.c b/kaleid/kernel/io/vga.c
index 6956df9..0230143 100644
--- a/kaleid/kernel/io/vga.c
+++ b/kaleid/kernel/io/vga.c
@@ -44,9 +44,7 @@ error_t bvgaflusher(Buffer_t *buf)
     ushort *fbp = BtGetBootInfo(video).framebufferAddr;
     const uchar color = 0xf;
 
-    assert(buf->lastLF == 0);
-
-    uchar *currentLine = buf->wp - buf->lineLen;
+    uchar *currentLine = buf->wp - buf->lineLen - buf->lastLF;
     uchar *ptr = (uchar *)lmax((size_t)buf->buf,
                                (size_t)currentLine
                                 - (buf->nLines - 1) * buf->lineLen);
diff --git a/kaleid/kernel/ke/panic.c b/kaleid/kernel/ke/panic.c
index 52555f3..c6cbb5a 100644
--- a/kaleid/kernel/ke/panic.c
+++ b/kaleid/kernel/ke/panic.c
@@ -28,6 +28,8 @@
 #include <kernel/sched.h>
 #include <kernel/panic.h>
 
+error_t vbprintf(Buffer_t *buf, const char *fmt, va_list ap);
+
 //
 // Failed assert() handler
 //
@@ -55,21 +57,29 @@ noreturn void KeStartPanic(const char *fmt, ...)
     PsCurProc = NULL;
     if (BStdOut == NULL) KeCrashSystem();
 
+    ExAttemptLock(&BStdOut->lock);
+
     if (fmt == NULL) {
         fmt = "(no message given)";
     }
 
     if (KePanicStr[0] != 0) {
-        KernLog("\nDouble panic!");
+        vbprintf(BStdOut, "\nDouble panic!", NULL);
         KeHaltCPU();
     }
+    
+    KePanicStr[0] = 1;
 
+    // We don't check vbprintf's output
+    // If it fails, what could we do anyway?
+    
+    vbprintf(BStdOut, "\nPanic!\n\n", NULL);
+    
     va_start(ap, fmt);
-    vsnprintf((char *)KePanicStr, PANICSTR_SIZE, fmt, ap);
+    vbprintf(BStdOut, fmt, ap);
     va_end(ap);
-
-    KernLog("\nPanic!\n\n");
-    KernLog((char *)KePanicStr);
+    
+    BStdOut->flusher(BStdOut);
 
     KeHaltCPU();
 }