UNDI ISR: save and restore 32-bit registers

As written, if the if the UNDI ISR call clobbers the upper halves of any of the GPRs (which by convention it is permitted to do, and by paranoia should be expected to do) then nothing in the interrupt handler will recover the state. Additionally, save/restore %fs and %gs out of sheer paranoia - it's a cheap enough operation, and may prevent problems due to poorly written UNDI stacks.
ipxe · Feb 11, 2008 · 621c288 · 621c288
1 parent 428c634
commit 621c288
Showing 1 changed file with 7 additions and 4 deletions.
diff --git a/src/arch/i386/drivers/net/undiisr.S b/src/arch/i386/drivers/net/undiisr.S
@@ -21,7 +21,9 @@ undiisr:
 	/* Preserve registers */
 	pushw	%ds
 	pushw	%es
-	pusha
+	pushw	%fs
+	pushw	%gs
+	pushal
 
 	/* Set up our segment registers */
 	movw	%cs:rm_ds, %ax
@@ -32,8 +34,7 @@ undiisr:
 	je	chain
 
 	/* Issue UNDI API call */
-	pushw	%ds
-	popw	%es
+	movw	%ax, %es
 	movw	$undinet_params, %di
 	movw	$PXENV_UNDI_ISR, %bx
 	movw	$PXENV_UNDI_ISR_IN_START, funcflag
@@ -62,7 +63,9 @@ chain:	/* Chain to next handler */
 	lcall	*undiisr_next_handler
 
 exit:	/* Restore registers and return */
-	popa
+	popal
+	popw	%gs
+	popw	%fs
 	popw	%es
 	popw	%ds
 	iret