Commit Graph

5 Commits

Author SHA1 Message Date
Warner Losh
9057f54d74 Fail to open efirt device when no EFI on system.
libefivar expects opening /dev/efi to indicate if the we can make efi
runtime calls. With a null routine, it was always succeeding leading
efi_variables_supported() to return the wrong value. Only succeed if
we have an efi_runtime table. Also, while I'm hear, out of an
abundance of caution, add a likely redundant check to make sure
efi_systbl is not NULL before dereferencing it. I know it can't be
NULL if efi_cfgtbl is non-NULL, but the compiler doesn't.
2017-08-08 20:44:16 +00:00
Ryan Libby
5e6f40bdef efi: restrict visibility of EFIABI_ATTR-declared functions
In-tree gcc (4.2) doesn't understand __attribute__((ms_abi))
(EFIABI_ATTR).  Avoid declaring functions with that attribute when the
compiler is detected to be gcc < 4.4.

Reviewed by:	kib, imp (previous version)
Approved by:	markj (mentor)
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D11636
2017-07-20 06:47:06 +00:00
Warner Losh
2faa9f8c8e Change the efi_get_table interface to a void ** so we can return the
pointer by dereferencing the pointer.

Reviewed by: kib@
MFC After: 2 weeks
Sponsored by: Netflix, Inc
2016-09-22 19:04:51 +00:00
Konstantin Belousov
bc3ad3a179 Add kernel interfaces to call EFI Runtime Services.
Runtime services require special execution environment for the call.
Besides that, OS must inform firmware about runtime virtual memory map
which will be active during the calls, with the SetVirtualAddressMap()
runtime call, done while the 1:1 mapping is still used.  There are two
complication: the SetVirtualAddressMap() effectively must be done from
loader, which needs to know kernel address map in advance.  More,
despite not explicitely mentioned in the specification, both 1:1 and
the map passed to SetVirtualAddressMap() must be active during the
SetVirtualAddressMap() call.  Second, there are buggy BIOSes which
require both mappings active during runtime calls as well, most likely
because they fail to identify all relocations to perform.

On amd64, we can get rid of both problems by providing 1:1 mapping for
the duration of runtime calls, by temprorary remapping user addresses.
As result, we avoid the need for loader to know about future kernel
address map, and avoid bugs in BIOSes.  Typically BIOS only maps
something in low 4G.  If not runtime bugs, we would take advantage of
the DMAP, as previous versions of this patch did.

Similar but more complicated trick can be used even for i386 and 32bit
runtime, if and when the EFI boot on i386 is supported.  We would need
a trampoline page, since potentially whole 4G of VA would be switched
on calls, instead of only userspace portion on amd64.

Context switches are disabled for the duration of the call, FPU access
is granted, and interrupts are not disabled.  The later is possible
because kernel is mapped during calls.

To test, the sysctl mib debug.efi_time is provided, setting it to 1
makes one call to EFI get_time() runtime service, on success the efitm
structure is printed to the control terminal.  Load efirt.ko, or add
EFIRT option to the kernel config, to enable code.

Discussed with:	emaste, imp
Tested by:	emaste (mac, qemu)
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2016-09-21 11:31:58 +00:00
Konstantin Belousov
559a7b209a Add a way for the architecture to specify the calling ABI for methods
in the EFI Runtime Services Table.  On amd64, the calling conventions
are MS.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-09-21 10:35:44 +00:00