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 <j...@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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