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Date:      Mon, 3 Jun 2019 15:32:42 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r348539 - in head/sys/amd64: amd64 include
Message-ID:  <201906031532.x53FWgcB077335@repo.freebsd.org>
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Author: kib
Date: Mon Jun  3 15:32:42 2019
New Revision: 348539
URL: https://svnweb.freebsd.org/changeset/base/348539

Log:
  amd64 ef_rt_arch_call: Preserve %rflags around call into EFI RT service.
  
  If service code faulted, we might end up unwinding with interrupts
  disabled.  Top-level kernel code should have interrupts enabled, which
  is enforced by checks.
  
  Save %rflags before entering EFI, and restore to the known good value
  on return.  This handles situation with disabled interrupts on fault
  and perhaps other potential bugs, e.g. invalid value for PSL_D.
  
  Reported and tested by:	Jan Martin Mikkelsen <janm@transactionware.com>
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/amd64/amd64/efirt_support.S
  head/sys/amd64/amd64/genassym.c
  head/sys/amd64/include/efi.h

Modified: head/sys/amd64/amd64/efirt_support.S
==============================================================================
--- head/sys/amd64/amd64/efirt_support.S	Mon Jun  3 15:28:37 2019	(r348538)
+++ head/sys/amd64/amd64/efirt_support.S	Mon Jun  3 15:32:42 2019	(r348539)
@@ -47,6 +47,9 @@ ENTRY(efi_rt_arch_call)
 	movq	%r13, EC_R13(%rdi)
 	movq	%r14, EC_R14(%rdi)
 	movq	%r15, EC_R15(%rdi)
+	pushfq
+	popq	%rax
+	movq	%rax, EC_RFLAGS(%rdi)
 	movq	PCPU(CURTHREAD), %rax
 	movq	%rdi, TD_MD+MD_EFIRT_TMP(%rax)
 	movq	PCPU(CURPCB), %rsi
@@ -98,6 +101,8 @@ efi_rt_arch_call_tail:
 	movq	EC_RBP(%rdi), %rbp
 	movq	EC_RSP(%rdi), %rsp
 	movq	EC_RBX(%rdi), %rbx
+	pushq	EC_RFLAGS(%rdi)
+	popfq
 
 	popq	%rbp
 	ret

Modified: head/sys/amd64/amd64/genassym.c
==============================================================================
--- head/sys/amd64/amd64/genassym.c	Mon Jun  3 15:28:37 2019	(r348538)
+++ head/sys/amd64/amd64/genassym.c	Mon Jun  3 15:32:42 2019	(r348539)
@@ -272,3 +272,4 @@ ASSYM(EC_R12, offsetof(struct efirt_callinfo, ec_r12))
 ASSYM(EC_R13, offsetof(struct efirt_callinfo, ec_r13));
 ASSYM(EC_R14, offsetof(struct efirt_callinfo, ec_r14));
 ASSYM(EC_R15, offsetof(struct efirt_callinfo, ec_r15));
+ASSYM(EC_RFLAGS, offsetof(struct efirt_callinfo, ec_rflags));

Modified: head/sys/amd64/include/efi.h
==============================================================================
--- head/sys/amd64/include/efi.h	Mon Jun  3 15:28:37 2019	(r348538)
+++ head/sys/amd64/include/efi.h	Mon Jun  3 15:32:42 2019	(r348539)
@@ -72,6 +72,7 @@ struct efirt_callinfo {
 	register_t	ec_r13;
 	register_t	ec_r14;
 	register_t	ec_r15;
+	register_t	ec_rflags;
 };
 
 #endif /* __AMD64_INCLUDE_EFI_H_ */

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