On Sat, May 14, 2022 at 10:13:54PM +0200, He He4 Huang wrote:
> iPXE added a workaround to raise TPL to TPL_CALLBACK always, but it
> would cause UEFI firmware exit boot service callback with the same TPL
> level cannot be executed. Worse, some UEFI modules set a pointer at exit
> boot service callback and use later, then will encounter exception /
> hang for invalid pointer which is not set to a correct one since the
> exit boot service callback is not executed.
>
> The solution is to restore the TPL to the original one but not always
> set it to TPL_CALLBACK.
> ---
> src/interface/efi/efi_timer.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/src/interface/efi/efi_timer.c b/src/interface/efi/efi_timer.c
> index 6427eb1d..24c506fc 100644
> --- a/src/interface/efi/efi_timer.c
> +++ b/src/interface/efi/efi_timer.c
> @@ -133,11 +133,18 @@ static unsigned long efi_currticks ( void ) {
> * EFI's violation of this assumption by falling back to a
> * simple free-running monotonic counter during shutdown.
> */
> + EFI_TPL Efi_OldTPL;
> + Efi_OldTPL=0;
> if ( efi_shutdown_in_progress ) {
> efi_jiffies++;
> } else {
> + Efi_OldTPL = bs->RaiseTPL( TPL_CALLBACK);
> bs->RestoreTPL ( efi_external_tpl );
> bs->RaiseTPL ( efi_internal_tpl );
> + if ( Efi_OldTPL != 0 ) {
> + bs->RestoreTPL(Efi_OldTPL);
> + }
> +
> }
>
> return ( efi_jiffies * ( TICKS_PER_SEC / EFI_JIFFIES_PER_SEC ) );
> --
> 2.35.1
>
Context for submitting that patch
is https://github.com/ipxe/ipxe/issues/349#issuecomment-1126793404
that comment says
This commit was part of the pull request #113. That pull request was
never merged, because, as far as i understand, the root issue seemed
to have been fixed with pull request #120 which was merged.
The problem we are seeing however is still exactly the one that was
discussed in #113 and #120 did not fix the problem entirely.
Spamfilter did probably what they can do: Dropping emails.
Here the patch twice. Once inline, probably mangled intransit,
the other one attached, hopefully untouched.
>From: He He4 Huang <huang...@lenovo.com>
Date: Sat, 14 May 2022 21:57:41 +0200
Subject: [PATCH] [efi] Restore the TPL to the original one
iPXE added a workaround to raise TPL to TPL_CALLBACK always, but it
would cause UEFI firmware exit boot service callback with the same TPL
level cannot be executed. Worse, some UEFI modules set a pointer at exit
boot service callback and use later, then will encounter exception /
hang for invalid pointer which is not set to a correct one since the
exit boot service callback is not executed.
The solution is to restore the TPL to the original one but not always
set it to TPL_CALLBACK.
---
src/interface/efi/efi_timer.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/src/interface/efi/efi_timer.c b/src/interface/efi/efi_timer.c
index 6427eb1d..24c506fc 100644
--- a/src/interface/efi/efi_timer.c
+++ b/src/interface/efi/efi_timer.c
@@ -133,11 +133,18 @@ static unsigned long efi_currticks ( void ) {
* EFI's violation of this assumption by falling back to a
* simple free-running monotonic counter during shutdown.
*/
+ EFI_TPL Efi_OldTPL;
+ Efi_OldTPL=0;
if ( efi_shutdown_in_progress ) {
efi_jiffies++;
} else {
+ Efi_OldTPL = bs->RaiseTPL( TPL_CALLBACK);
bs->RestoreTPL ( efi_external_tpl );
bs->RaiseTPL ( efi_internal_tpl );
+ if ( Efi_OldTPL != 0 ) {
+ bs->RestoreTPL(Efi_OldTPL);
+ }
+
}
return ( efi_jiffies * ( TICKS_PER_SEC / EFI_JIFFIES_PER_SEC ) );
--
2.35.1
Groeten
Geert Stappers
--
Silence is hard to parse
>From 39e1be240ba399678e070be3aac6694862238bb9 Mon Sep 17 00:00:00 2001
From: He He4 Huang <huang...@lenovo.com>
Date: Sat, 14 May 2022 21:57:41 +0200
Subject: [PATCH] [efi] Restore the TPL to the original one
iPXE added a workaround to raise TPL to TPL_CALLBACK always, but it
would cause UEFI firmware exit boot service callback with the same TPL
level cannot be executed. Worse, some UEFI modules set a pointer at exit
boot service callback and use later, then will encounter exception /
hang for invalid pointer which is not set to a correct one since the
exit boot service callback is not executed.
The solution is to restore the TPL to the original one but not always
set it to TPL_CALLBACK.
---
src/interface/efi/efi_timer.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/src/interface/efi/efi_timer.c b/src/interface/efi/efi_timer.c
index 6427eb1d..24c506fc 100644
--- a/src/interface/efi/efi_timer.c
+++ b/src/interface/efi/efi_timer.c
@@ -133,11 +133,18 @@ static unsigned long efi_currticks ( void ) {
* EFI's violation of this assumption by falling back to a
* simple free-running monotonic counter during shutdown.
*/
+ EFI_TPL Efi_OldTPL;
+ Efi_OldTPL=0;
if ( efi_shutdown_in_progress ) {
efi_jiffies++;
} else {
+ Efi_OldTPL = bs->RaiseTPL( TPL_CALLBACK);
bs->RestoreTPL ( efi_external_tpl );
bs->RaiseTPL ( efi_internal_tpl );
+ if ( Efi_OldTPL != 0 ) {
+ bs->RestoreTPL(Efi_OldTPL);
+ }
+
}
return ( efi_jiffies * ( TICKS_PER_SEC / EFI_JIFFIES_PER_SEC ) );
--
2.35.1
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