[pxeprefix] Ensure that UNDI IRQ is disabled before starting iPXE

When using the undionly.kkpxe binary (which is never recommended), the
UNDI interrupt may still be enabled when iPXE starts up.  If the PXE
base code interrupt handler is not well-behaved, this can result in
undefined behaviour when interrupts are first enabled (e.g. for
entropy gathering, or for allowing the timer tick to occur).

Fix by detecting and disabling the UNDI interrupt during the prefix
code.

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

diff --git a/src/arch/x86/drivers/net/undinet.c b/src/arch/x86/drivers/net/undinet.c
index 43cb18bfe106b77f99e80d619b260c5735cf8d45..cdb39c74fae92a6fdf6ccdbea76af670bf69c077 100644 (file)
--- a/src/arch/x86/drivers/net/undinet.c
+++ b/src/arch/x86/drivers/net/undinet.c
@@ -972,6 +972,10 @@ int undinet_probe ( struct undi_device *undi, struct device *dev ) {
        }
        DBGC ( undinic, "UNDINIC %p has MAC address %s and IRQ %d\n",
               undinic, eth_ntoa ( netdev->hw_addr ), undinic->irq );
+       if ( undinic->irq ) {
+               /* Sanity check - prefix should have disabled the IRQ */
+               assert ( ! irq_enabled ( undinic->irq ) );
+       }
 
        /* Get interface information */
        memset ( &undi_iface, 0, sizeof ( undi_iface ) );

diff --git a/src/arch/x86/prefix/pxeprefix.S b/src/arch/x86/prefix/pxeprefix.S
index 0842fcac44ff582434a50e358c71ca82206a4cee..2ac1bc76d464f8398d90669b28979ca82248357e 100644 (file)
--- a/src/arch/x86/prefix/pxeprefix.S
+++ b/src/arch/x86/prefix/pxeprefix.S
@@ -1,6 +1,7 @@
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
 
 #define PXENV_UNDI_SHUTDOWN            0x0005
+#define PXENV_UNDI_GET_INFORMATION     0x000c
 #define        PXENV_UNDI_GET_NIC_TYPE         0x0012
 #define PXENV_UNDI_GET_IFACE_INFO      0x0013
 #define        PXENV_STOP_UNDI                 0x0015
@@ -380,6 +381,33 @@ no_physical_device:
 
 99:
 
+/*****************************************************************************
+ * Get IRQ number
+ *****************************************************************************
+ */
+get_irq:
+       /* Issue PXENV_UNDI_GET_INFORMATION */
+       movw    $PXENV_UNDI_GET_INFORMATION, %bx
+       call    pxe_call
+       jnc     1f
+       call    print_pxe_error
+       jmp     99f
+1:     /* Check for a valid IRQ number */
+       movw    ( pxe_parameter_structure + 0x04 ), %ax
+       testw   %ax, %ax
+       jz      99f
+       cmpw    $15, %ax
+       ja      99f
+       /* Store IRQ number */
+       movw    %ax, undi_irq
+       movw    $10f, %si
+       call    print_message
+       call    print_word
+       .section ".prefix.data", "aw", @progbits
+10:    .asciz  ", IRQ "
+       .previous
+99:
+
 /*****************************************************************************
  * Determine interface type
  *****************************************************************************
@@ -470,6 +498,30 @@ pxe_cmdline:
        .long   0
        .previous
 
+/*****************************************************************************
+ * Ensure NIC interrupt is disabled
+ *****************************************************************************
+ */
+disable_irq:
+       /* Check for a recorded IRQ number */
+       movw    undi_irq, %cx
+       testw   %cx, %cx
+       jz      99f
+       /* Calculate IMR */
+       movw    %cx, %dx
+       shlw    $4, %dx
+       andb    $0x80, %dl
+       orb     $0x21, %dl
+       /* Calculate mask value */
+       movb    $0x01, %bl
+       andb    $0x07, %cl
+       shlb    %cl, %bl
+       /* Mask interrupt */
+       inb     %dx, %al
+       orb     %bl, %al
+       outb    %al, %dx
+99:
+
 /*****************************************************************************
  * Leave NIC in a safe state
  *****************************************************************************
@@ -759,6 +811,8 @@ undi_data_segoff:
 undi_data_size:                .word 0
 undi_data_segment:     .word 0
 
+undi_irq:              .word 0
+
 pxe_hacks:             .word 0
 
 /* The following fields are part of a struct undi_device */