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amd64 ef_rt_arch_call: Preserve %rflags around call into EFI RT service.

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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
This commit is contained in:
Konstantin Belousov 2019-06-03 15:32:42 +00:00
parent f6e5ddff6b
commit 185f7e0a9d
3 changed files with 7 additions and 0 deletions
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5
sys/amd64/amd64/efirt_support.S
View File

@ -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

1
sys/amd64/amd64/genassym.c
View File

@ -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));

1
sys/amd64/include/efi.h
View File

@ -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_ */