From: Michael Brown <mcb30@ipxe.org>
Date: Tue, 12 Jan 2016 08:27:59 +0000 (+0000)
Subject: [i386] Add check_bios_interrupts() debug function
X-Git-Tag: v1.20.1~631
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=83c8f2e8e352e676d9951dda58b74e587101c0b4;p=thirdparty%2Fipxe.git

[i386] Add check_bios_interrupts() debug function

Provide a debug function check_bios_interrupts() to look for changes
to the interrupt vector table.  This can be useful when investigating
the behaviour (including crashes) of external PXE NBPs.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---

diff --git a/src/arch/i386/include/biosint.h b/src/arch/i386/include/biosint.h
index 67d6a3811..f47116f70 100644
--- a/src/arch/i386/include/biosint.h
+++ b/src/arch/i386/include/biosint.h
@@ -29,5 +29,6 @@ extern void hook_bios_interrupt ( unsigned int interrupt, unsigned int handler,
 extern int unhook_bios_interrupt ( unsigned int interrupt,
 				   unsigned int handler,
 				   struct segoff *chain_vector );
+extern void check_bios_interrupts ( void );
 
 #endif /* BIOSINT_H */
diff --git a/src/arch/i386/interface/pcbios/biosint.c b/src/arch/i386/interface/pcbios/biosint.c
index 3b8e80438..667e9ed81 100644
--- a/src/arch/i386/interface/pcbios/biosint.c
+++ b/src/arch/i386/interface/pcbios/biosint.c
@@ -90,3 +90,30 @@ int unhook_bios_interrupt ( unsigned int interrupt, unsigned int handler,
 	hooked_bios_interrupts--;
 	return 0;
 }
+
+/**
+ * Dump changes to interrupt vector table (for debugging)
+ *
+ */
+void check_bios_interrupts ( void ) {
+	static struct segoff vectors[256];
+	static uint8_t initialised;
+	struct segoff vector;
+	unsigned int i;
+
+	/* Print any changed interrupt vectors */
+	for ( i = 0; i < ( sizeof ( vectors ) / sizeof ( vectors[0] ) ); i++ ) {
+		copy_from_real ( &vector, 0, ( i * sizeof ( vector ) ),
+				 sizeof ( vector ) );
+		if ( memcmp ( &vector, &vectors[i], sizeof ( vector ) ) == 0 )
+			continue;
+		if ( initialised ) {
+			dbg_printf ( "INT %02x changed %04x:%04x => "
+				     "%04x:%04x\n", i, vectors[i].segment,
+				     vectors[i].offset, vector.segment,
+				     vector.offset );
+		}
+		memcpy ( &vectors[i], &vector, sizeof ( vectors[i] ) );
+	}
+	initialised = 1;
+}