[librm] Ensure that inline code symbols are unique
Commit 6149e0a ("[librm] Provide symbols for inline code placed into
other sections") may cause build failures due to duplicate label names
if the compiler chooses to duplicate inline assembly code.
Fix by using the "%=" special format string to include a
guaranteed-unique number within the label name.
The "%=" will be expanded only if constraints exist for the inline
assembly. This fix therefore requires that all REAL_CODE() fragments
use a (possibly empty) constraint list.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[librm] Provide symbols for inline code placed into other sections
Provide symbols constructed from the object name and line number for
code fragments placed into alternative sections, such as inline
REAL_CODE() assembly placed into .text16. This simplifies the
debugging task of finding the source code corresponding to a given
instruction pointer.
Note that we cannot use __FUNCTION__ since it is not a preprocessor
macro and so cannot be concatenated with string literals.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[rng] Use fixed-point calculations for min-entropy quantities
We currently perform various min-entropy calculations using build-time
floating-point arithmetic. No floating-point code ends up in the
final binary, since the results are eventually converted to integers
and asserted to be compile-time constants.
Though this mechanism is undoubtedly cute, it inhibits us from using
"-mno-sse" to prevent the use of SSE registers by the compiler.
Fix by using fixed-point arithmetic instead.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[time] Add support for the ACPI power management timer
Allow the ACPI power management timer to be used if enabled via
TIMER_ACPI in config/timer.h. This provides an alternative timer on
systems where the standard 8254 PIT is unavailable or unreliable.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[librm] Add facility to provide register and stack dump for CPU exceptions
When DEBUG=librm_mgmt is enabled, intercept CPU exceptions and provide
a register and stack dump, then drop to an emergency shell. Exiting
from the shell will almost certainly not work, but this provides an
opportunity to view the register and stack dump and carry out some
basic debugging.
Note that we can intercept only the first 8 CPU exceptions, since a
PXE ROM is not permitted to rebase the PIC.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
For some CPUID leaves (e.g. %eax=0x00000004), the result depends on
the input value of %ecx. Allow this subfunction number to be
specified as a parameter to the cpuid() wrapper.
The subfunction number is exposed via the ${cpuid/...} settings
mechanism using the syntax
${cpuid/<subfunction>.0x40.<register>.<function>}
e.g.
${cpuid/0.0x40.0.0x0000000b}
${cpuid/1.0x40.0.0x0000000b}
to retrieve the CPU topology information.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
As of commit 10d19bd ("[pxe] Always retrieve cached DHCPACK and apply
to relevant network device"), the UNDI driver has been the only user
of pxeparent_call(). Remove the unnecessary layer of abstraction by
refactoring this code back into undinet.c, and fix the ability of
undiisr.S to fall back to chaining to the original handler if we were
unable to unhook our own ISR.
This effectively reverts commit 337e1ed ("[pxe] Separate parent PXE
API caller from UNDINET driver").
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow the active timer (providing udelay() and currticks()) to be
selected at runtime based on probing during the INIT_EARLY stage of
initialisation.
TICKS_PER_SEC is now a fixed compile-time constant for all builds, and
is independent of the underlying clock tick rate. We choose the value
1024 to allow multiplications and divisions on seconds to be converted
to bit shifts.
TICKS_PER_MS is defined as 1, allowing multiplications and divisions
on milliseconds to be omitted entirely. The 2% inaccuracy in this
definition is negligible when using the standard BIOS timer (running
at around 18.2Hz).
TIMER_RDTSC now checks for a constant TSC before claiming to be a
usable timer. (This timer can be tested in KVM via the command-line
option "-cpu host,+invtsc".)
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[undi] Clean up driver and device name information
Fix the <NULL> driver name reported by "ifstat" when using the undipci
driver (due to the unnecessary extra device node inserted as a child
of the PCI device).
Remove the "UNDI-" prefix from device names since the driver name is
also now visible via "ifstat", and tidy up the device name to match
the format used by standard PCI devices.
The output from "ifstat" now resembles:
iPXE> ifstat
net0: 52:54:00:12:34:56 using undipci on 0000:00:03.0
iPXE> ifstat
net0: 52:54:00:12:34:56 using undionly on 0000:00:03.0
Signed-off-by: Michael Brown <mcb30@ipxe.org>
On some platforms (observed in a small subset of Microsoft Azure
(Hyper-V) virtual machines), the RTC appears to be incapable of
generating an interrupt via the legacy PIC. The RTC status registers
show that a periodic interrupt has been asserted, but the PIC IRR
shows that IRQ8 remains inactive.
On such systems, iPXE will currently freeze during the "iPXE
initialising devices..." message.
Work around this problem by checking that RTC interrupts are being
raised before returning from rtc_entropy_enable(). If no interrupt is
seen within 100ms, then we assume that the RTC interrupt mechanism is
broken. In these circumstances, iPXE will continue to initialise but
any subsequent attempt to generate entropy will fail. In particular,
HTTPS connections will fail with an error indicating that no entropy
is available.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[tcpip] Do not fall back to using unoptimised TCP/IP checksumming
Require architecture-specific code to make a deliberate choice to use
the unoptimised generic_tcpip_continue_chksum() function, if there is
no optimised version available.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[int13] Allow default drive to be specified via "san-drive" setting
The DHCP option 175.189 has been defined (by us) since 2006 as
containing the drive number to be used for a SAN boot, but has never
been automatically used as such by iPXE.
Use this option (if specified) to override the default SAN drive
number.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[librm] Add support for running in 64-bit long mode
Add support for running the BIOS version of iPXE in 64-bit long mode.
A 64-bit BIOS version of iPXE can be built using e.g.
make bin-x86_64-pcbios/ipxe.usb
make bin-x86_64-pcbios/8086100e.mrom
The 64-bit BIOS version should appear to function identically to the
normal 32-bit BIOS version. The physical memory layout is unaltered:
iPXE is still relocated to the top of the available 32-bit address
space. The code is linked to a virtual address of 0xffffffffeb000000
(in the negative 2GB as required by -mcmodel=kernel), with 4kB pages
created to cover the whole of .textdata. 2MB pages are created to
cover the whole of the 32-bit address space.
The 32-bit portions of the code run with VIRTUAL_CS and VIRTUAL_DS
configured such that truncating a 64-bit virtual address gives a
32-bit virtual address pointing to the same physical location.
The stack pointer remains as a physical address when running in long
mode (although the .stack section is accessible via the negative 2GB
virtual address); this is done in order to simplify the handling of
interrupts occurring while executing a portion of 32-bit code with
flat physical addressing via PHYS_CODE().
Interrupts may be enabled in either 64-bit long mode, 32-bit protected
mode with virtual addresses, 32-bit protected mode with physical
addresses, or 16-bit real mode. Interrupts occurring in any mode
other than real mode will be reflected down to real mode and handled
by whichever ISR is hooked into the BIOS interrupt vector table.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
In a 64-bit build, the entirety of the 32-bit address space is
identity-mapped and so any valid physical address may immediately be
used as a virtual address. Conversely, a virtual address that is
already within the 32-bit address space may immediately be used as a
physical address.
A valid virtual address that lies outside the 32-bit address space
must be an address within .textdata, and so can be converted to a
physical address by adding virt_offset.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[librm] Mark virt_offset, text16, data16, rm_cs, and rm_ds as constant
The physical locations of .textdata, .text16 and .data16 are constant
from the point of view of C code. Mark the relevant variables as
constant to allow gcc to optimise out redundant reads.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[librm] Add phys_call() wrapper for calling code with physical addressing
Add a phys_call() wrapper function (analogous to the existing
real_call() wrapper function) for calling code with flat physical
addressing, and use this wrapper within the PHYS_CODE() macro.
Move the relevant functionality inside librm.S, where it more
naturally belongs.
The COMBOOT code currently uses explicit calls to _virt_to_phys and
_phys_to_virt. These will need to be rewritten if our COMBOOT support
is ever generalised to be able to run in a 64-bit build.
Specifically:
- com32_exec_loop() should be restructured to use PHYS_CODE()
- com32_wrapper.S should be restructured to use an equivalent of
prot_call(), passing parameters via a struct i386_all_regs
- there appears to be no need for com32_wrapper.S to switch between
external and internal stacks; this could be omitted to simplify
the design.
For now, librm.S continues to expose _virt_to_phys and _phys_to_virt
for use by com32.c and com32_wrapper.S. Similarly, librm.S continues
to expose _intr_to_virt for use by gdbidt.S.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The bulk of the iPXE binary (the .textdata section) is physically
relocated at runtime to the top of the 32-bit address space in order
to allow space for an OS to be loaded. The relocation is achieved
with the assistance of segmentation: we adjust the code and data
segment bases so that the link-time addresses remain valid.
Segmentation is not available (for normal code and data segments) in
long mode. We choose to compile the C code with -mcmodel=kernel and
use a link-time address of 0xffffffffeb000000. This choice allows us
to identity-map the entirety of the 32-bit address space, and to alias
our chosen link-time address to the physical location of our .textdata
section. (This requires the .textdata section to always be aligned to
a page boundary.)
We simultaneously choose to set the 32-bit virtual address segment
bases such that the link-time addresses may simply be truncated to 32
bits in order to generate a valid 32-bit virtual address. This allows
symbols in .textdata to be trivially accessed by both 32-bit and
64-bit code.
There is no (sensible) way in 32-bit assembly code to generate the
required R_X86_64_32S relocation records for these truncated symbols.
However, subtracting the fixed constant 0xffffffff00000000 has the
same effect as truncation, and can be represented in a standard
R_X86_64_32 relocation record. We define the VIRTUAL() macro to
abstract away this truncation operation, and apply it to all
references by 32-bit (or 16-bit) assembly code to any symbols within
the .textdata section.
We define "virt_offset" for a 64-bit build as "the value to be added
to an address within .textdata in order to obtain its physical
address". With this definition, the low 32 bits of "virt_offset" can
be treated by 32-bit code as functionally equivalent to "virt_offset"
in a 32-bit build.
We define "text16" and "data16" for a 64-bit build as the physical
addresses of the .text16 and .data16 sections. Since a physical
address within the 32-bit address space may be used directly as a
64-bit virtual address (thanks to the identity map), this definition
provides the most natural access to variables in .text16 and .data16.
Note that this requires a minor adjustment in prot_to_real(), which
accesses .text16 using 32-bit virtual addresses.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[librm] Transition to protected mode within init_librm()
Long-mode operation will require page tables, which are too large to
sensibly fit in our .data16 segment in base memory.
Add a portion of init_librm() running in 32-bit protected mode to
provide access to high memory. Use this portion of init_librm() to
initialise the .textdata variables "virt_offset", "text16", and
"data16", eliminating the redundant (re)initialisation currently
performed on every mode transition as part of real_to_prot().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Move most arch/i386 files to arch/x86, and adjust the contents of the
Makefiles and the include/bits/*.h headers to reflect the new
locations.
This patch makes no substantive code changes, as can be seen using a
rename-aware diff (e.g. "git show -M5").
This patch does not make the pcbios platform functional for x86_64; it
merely allows it to compile without errors.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[vmware] Expose GuestRPC mechanism in 64-bit builds
The GuestRPC mechanism (used for VMWARE_SETTINGS and CONSOLE_VMWARE)
does not use any real-mode code and so can be exposed in both 64-bit
and 32-bit builds.
Reported-by: Matthew Helton <mwhelton@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[xen] Wait for and clear XenStore event before receiving data
Older, out-of-tree Xen kernel modules (such as those provided with
SuSE Linux Enterprise Server 11) do not clear the leftover "event
pending" bit when opening an event channel. Consequently, no event is
ever delivered to indicate that there is information in the XenStore
ring buffer, and the system hangs shortly after loading the
xen-platform-pci kernel module.
Work around this problem by always waiting for the XenStore event
channel to be signalled, and clearing the event before processing the
received data.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[int13con] Add basic ability to log to a local disk via INT 13
Several popular public cloud providers do not provide any sensible
mechanism for obtaining debug output from an OS which is failing to
boot. For example, Amazon EC2 provides the "Get System Log" facility,
which occasionally deigns to report a random subset of the characters
emitted via the VM's serial port, but usually returns only a blank
screen. (Amazingly, this is still superior to the debugging
facilities provided by Azure.)
Work around these shortcomings by adding a console type which sends
output to a magically detected raw disk partition, and including such
a partition within any iPXE .usb-format image.
To use this facility:
- build an iPXE .usb image with CONSOLE_INT13 enabled
- boot the cloud VM from this image
- after the boot fails, attach the VM's boot disk to a second VM
- from this second VM, use "less -f -R /dev/sdb3" (or similar) to
view the iPXE output.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The valgrind headers are not x86-specific; they detect the CPU
architecture and contain inline assembly for multiple architectures.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[legal] Relicense files under GPL2_OR_LATER_OR_UBDL
These files cannot be automatically relicensed by util/relicense.pl
since they either contain unusual but trivial contributions (such as
the addition of __nonnull function attributes), or contain lines
dating back to the initial git revision (and so require manual
knowledge of the code's origin).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[timer] Rewrite the 8254 Programmable Interval Timer support
The 8254 timer code (used to implement udelay()) has an unknown
provenance. Rewrite this code to avoid potential licensing
uncertainty.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
As with memcpy(), we can reduce the code size (by an average of 0.2%)
by giving the compiler more visibility into what memset() is doing,
and by avoiding the "rep" prefix on short fixed-length sequences of
string operations.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some of the C library string functions have an unknown provenance.
Reimplement all such functions to avoid potential licensing
uncertainty.
Remove the inline-assembler versions of strlen(), memswap(), and
strncmp(); these save a minimal amount of space (around 40 bytes in
total) and are not performance-critical.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add basic support for Xen PV-HVM domains (detected via the Xen
platform PCI device with IDs 5853:0001), including support for
accessing configuration via XenStore and enumerating devices via
XenBus.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[ioapi] Fail ioremap() when attempting to map a zero bus address
When a 32-bit iPXE binary is running on a system which allocates PCI
memory BARs above 4GB, our PCI subsystem will return the base address
for any such BARs as zero (with a warning message if DEBUG=pci is
enabled). Currently, ioremap() will happily map an address pointing
to the start of physical memory, providing no sensible indication of
failure.
Fix by always returning NULL if we are asked to ioremap() a zero bus
address.
With a totally flat memory model (e.g. under EFI), this provides an
accurate failure indication since no PCI peripheral will be mapped to
the zero bus address.
With the librm memory model, there is the possibility of a spurious
NULL return from ioremap() if the bus address happens to be equal to
virt_offset. Under the current virtual memory map, the NULL virtual
address will always be the start of .textdata, and so this problem
cannot occur; a NULL return from ioremap() will always be an accurate
failure indication.
Debugged-by: Anton D. Kachalov <mouse@yandex-team.ru>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown