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[comboot] Restore the real-mode stack pointer on exit from a COMBOOT image

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COMBOOT images use INTs to issue API calls; these end up making calls
into gPXE from real mode, and so temporarily change the real-mode
stack pointer.  When our COMBOOT code uses a longjmp() to implement
the various "exit COMBOOT image" API calls, this leaves the real-mode
stack pointer stuck with its temporary value, which causes problems if
we eventually try to exit out of gPXE back to the BIOS.

Fix by adding rmsetjmp() and rmlongjmp() calls (analogous to
sigsetjmp()/siglongjmp()); these save and restore the additional state
needed for real-mode calls to function correctly.
This commit is contained in:
Michael Brown
2009-02-17 03:33:26 +00:00
parent 7f903f03af
commit 5026a35fef
5 changed files with 40 additions and 14 deletions
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2
src/arch/i386/image/comboot.c
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@@ -133,7 +133,7 @@ static int comboot_exec ( struct image *image ) {
userptr_t seg_userptr = real_to_user ( COMBOOT_PSP_SEG, 0 );
int state;
state = setjmp ( comboot_return );
state = rmsetjmp ( comboot_return );
switch ( state ) {
case 0: /* First time through; invoke COMBOOT program */