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[prefix] Use %cs as implicit parameter to uninstall()

romprefix.S currently calls uninstall() with an invalid value in %ax.
Consequently, base memory is not freed after a ROM boot attempt (or
after entering iPXE during POST).

The uninstall() function is physically present in .text16, and so can
use %cs to determine the .text16 segment address.  The .data16 segment
address is not required, since uninstall() is called only by code
paths which set up .data16 to immediately follow .text16.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
tags/v1.20.1
Michael Brown 11 anni fa
parent
commit
0d4a760ffc
1 ha cambiato i file con 6 aggiunte e 6 eliminazioni
  1. 6
    6
      src/arch/i386/prefix/libprefix.S

+ 6
- 6
src/arch/i386/prefix/libprefix.S Vedi File

@@ -545,8 +545,7 @@ alloc_basemem:
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  * Free space allocated with alloc_basemem.
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  *
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  * Parameters:
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- *   %ax : .text16 segment address
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- *   %bx : .data16 segment address
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+ *   none (.text16 segment address is implicit in %cs)
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  * Returns:
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  *   %ax : 0 if successfully freed
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  * Corrupts:
@@ -559,14 +558,14 @@ alloc_basemem:
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 free_basemem:
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 	/* Preserve registers */
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 	pushw	%fs
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+	pushw	%ax
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 	/* Check FBMS counter */
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-	pushw	%ax
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+	movw	%cs, %ax
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 	shrw	$6, %ax
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 	pushw	$0x40
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 	popw	%fs
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 	cmpw	%ax, %fs:0x13
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-	popw	%ax
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 	jne	1f
571 570
 
572 571
 	/* Check hooked interrupt count */
@@ -574,6 +573,7 @@ free_basemem:
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 	jne	1f
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 	/* OK to free memory */
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+	movw	%cs, %ax
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 	addw	$_text16_memsz_pgh, %ax
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 	addw	$_data16_memsz_pgh, %ax
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 	shrw	$6, %ax
@@ -581,6 +581,7 @@ free_basemem:
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 	xorw	%ax, %ax
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 1:	/* Restore registers and return */
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+	popw	%ax
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 	popw	%fs
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 	ret
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 	.size free_basemem, . - free_basemem
@@ -872,8 +873,7 @@ close_payload:
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  * Uninstall all text and data segments.
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  *
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  * Parameters:
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- *   %ax  : .text16 segment address
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- *   %bx  : .data16 segment address
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+ *   none (.text16 segment address is implicit in %cs)
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  * Returns:
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  *   none
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  * Corrupts:

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