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[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>
tags/v1.20.1
Michael Brown 9 years ago
parent
commit
83c8f2e8e3
2 changed files with 28 additions and 0 deletions
  1. 1
    0
      src/arch/i386/include/biosint.h
  2. 27
    0
      src/arch/i386/interface/pcbios/biosint.c

+ 1
- 0
src/arch/i386/include/biosint.h View File

@@ -29,5 +29,6 @@ extern void hook_bios_interrupt ( unsigned int interrupt, unsigned int handler,
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 extern int unhook_bios_interrupt ( unsigned int interrupt,
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 				   unsigned int handler,
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 				   struct segoff *chain_vector );
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+extern void check_bios_interrupts ( void );
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 #endif /* BIOSINT_H */

+ 27
- 0
src/arch/i386/interface/pcbios/biosint.c View File

@@ -90,3 +90,30 @@ int unhook_bios_interrupt ( unsigned int interrupt, unsigned int handler,
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 	hooked_bios_interrupts--;
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 	return 0;
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 }
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+
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+/**
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+ * Dump changes to interrupt vector table (for debugging)
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+ *
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+ */
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+void check_bios_interrupts ( void ) {
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+	static struct segoff vectors[256];
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+	static uint8_t initialised;
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+	struct segoff vector;
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+	unsigned int i;
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+
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+	/* Print any changed interrupt vectors */
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+	for ( i = 0; i < ( sizeof ( vectors ) / sizeof ( vectors[0] ) ); i++ ) {
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+		copy_from_real ( &vector, 0, ( i * sizeof ( vector ) ),
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+				 sizeof ( vector ) );
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+		if ( memcmp ( &vector, &vectors[i], sizeof ( vector ) ) == 0 )
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+			continue;
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+		if ( initialised ) {
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+			dbg_printf ( "INT %02x changed %04x:%04x => "
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+				     "%04x:%04x\n", i, vectors[i].segment,
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+				     vectors[i].offset, vector.segment,
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+				     vector.offset );
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+		}
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+		memcpy ( &vectors[i], &vector, sizeof ( vectors[i] ) );
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+	}
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+	initialised = 1;
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+}

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