litmus-rt-ext-res.git/arch/x86/boot, branch EXT-RES

Checkpoint1(Updated)

2020-09-23T17:28:33+00:00

Encounters problem where task waits an extra period due to
sleep(unresolved)

x86/boot: Fix BSS corruption/overwrite bug in early x86 kernel startup

2017-05-20T12:28:36+00:00

commit d594aa0277e541bb997aef0bc0a55172d8138340 upstream.

The minimum size for a new stack (512 bytes) setup for arch/x86/boot components
when the bootloader does not setup/provide a stack for the early boot components
is not "enough".

The setup code executing as part of early kernel startup code, uses the stack
beyond 512 bytes and accidentally overwrites and corrupts part of the BSS
section. This is exposed mostly in the early video setup code, where
it was corrupting BSS variables like force_x, force_y, which in-turn affected
kernel parameters such as screen_info (screen_info.orig_video_cols) and
later caused an exception/panic in console_init().

Most recent boot loaders setup the stack for early boot components, so this
stack overwriting into BSS section issue has not been exposed.

Signed-off-by: Ashish Kalra 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20170419152015.10011-1-ashishkalra@Ashishs-MacBook-Pro.local
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86/build: Build compressed x86 kernels as PIE when !CONFIG_RELOCATABLE as well

2016-11-21T10:05:28+00:00

Since the bootloader may load the compressed x86 kernel at any address,
it should always be built as PIE, not just when CONFIG_RELOCATABLE=y.

Otherwise, linker in binutils 2.27 will optimize GOT load into the
absolute address when building the compressed x86 kernel as a non-PIE
executable.

Signed-off-by: H.J. Lu 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
[ Small wording changes. ]
Signed-off-by: Ingo Molnar

x86/boot: Fail the boot if !M486 and CPUID is missing

2016-11-21T08:04:32+00:00

Linux will have all kinds of sporadic problems on systems that don't
have the CPUID instruction unless CONFIG_M486=y.  In particular,
sync_core() will explode.

I believe that these kernels had a better chance of working before
commit 05fb3c199bb0 ("x86/boot: Initialize FPU and X86_FEATURE_ALWAYS
even if we don't have CPUID").  That commit inadvertently fixed a
serious bug: we used to fail to detect the FPU if CPUID wasn't
present.  Because we also used to forget to set X86_FEATURE_ALWAYS, we
end up with no cpu feature bits set at all.  This meant that
alternative patching didn't do anything and, if paravirt was disabled,
we could plausibly finish the entire boot process without calling
sync_core().

Rather than trying to work around these issues, just have the kernel
fail loudly if it's running on a CPUID-less 486, doesn't have CPUID,
and doesn't have CONFIG_M486 set.

Reported-by: Matthew Whitehead 
Signed-off-by: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/70eac6639f23df8be5fe03fa1984aedd5d40077a.1479598603.git.luto@kernel.org
Signed-off-by: Ingo Molnar

Merge tag 'efi-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi into efi/core

2016-09-13T18:21:55+00:00

Pull EFI updates from Matt Fleming:

"* Refactor the EFI memory map code into architecture neutral files
   and allow drivers to permanently reserve EFI boot services regions
   on x86, as well as ARM/arm64 - Matt Fleming

 * Add ARM support for the EFI esrt driver - Ard Biesheuvel

 * Make the EFI runtime services and efivar API interruptible by
   swapping spinlocks for semaphores - Sylvain Chouleur

 * Provide the EFI identity mapping for kexec which allows kexec to
   work on SGI/UV platforms with requiring the "noefi" kernel command
   line parameter - Alex Thorlton

 * Add debugfs node to dump EFI page tables on arm64 - Ard Biesheuvel

 * Merge the EFI test driver being carried out of tree until now in
   the FWTS project - Ivan Hu

 * Expand the list of flags for classifying EFI regions as "RAM" on
   arm64 so we align with the UEFI spec - Ard Biesheuvel

 * Optimise out the EFI mixed mode if it's unsupported (CONFIG_X86_32)
   or disabled (CONFIG_EFI_MIXED=n) and switch the early EFI boot
   services function table for direct calls, alleviating us from
   having to maintain the custom function table - Lukas Wunner

 * Miscellaneous cleanups and fixes"

Signed-off-by: Ingo Molnar

x86/efi: Allow invocation of arbitrary boot services

2016-09-09T15:08:57+00:00

We currently allow invocation of 8 boot services with efi_call_early().
Not included are LocateHandleBuffer and LocateProtocol in particular.
For graphics output or to retrieve PCI ROMs and Apple device properties,
we're thus forced to use the LocateHandle + AllocatePool + LocateHandle
combo, which is cumbersome and needs more code.

The ARM folks allow invocation of the full set of boot services but are
restricted to our 8 boot services in functions shared across arches.

Thus, rather than adding just LocateHandleBuffer and LocateProtocol to
struct efi_config, let's rework efi_call_early() to allow invocation of
arbitrary boot services by selecting the 64 bit vs 32 bit code path in
the macro itself.

When compiling for 32 bit or for 64 bit without mixed mode, the unused
code path is optimized away and the binary code is the same as before.
But on 64 bit with mixed mode enabled, this commit adds one compare
instruction to each invocation of a boot service and, depending on the
code path selected, two jump instructions. (Most of the time gcc
arranges the jumps in the 32 bit code path.) The result is a minuscule
performance penalty and the binary code becomes slightly larger and more
difficult to read when disassembled. This isn't a hot path, so these
drawbacks are arguably outweighed by the attainable simplification of
the C code. We have some overhead anyway for thunking or conversion
between calling conventions.

The 8 boot services can consequently be removed from struct efi_config.

No functional change intended (for now).

Example -- invocation of free_pool before (64 bit code path):
0x2d4      movq  %ds:efi_early, %rdx          ; efi_early
0x2db      movq  %ss:arg_0-0x20(%rsp), %rsi
0x2e0      xorl  %eax, %eax
0x2e2      movq  %ds:0x28(%rdx), %rdi         ; efi_early->free_pool
0x2e6      callq *%ds:0x58(%rdx)              ; efi_early->call()

Example -- invocation of free_pool after (64 / 32 bit mixed code path):
0x0dc      movq  %ds:efi_early, %rax          ; efi_early
0x0e3      cmpb  $0, %ds:0x28(%rax)           ; !efi_early->is64 ?
0x0e7      movq  %ds:0x20(%rax), %rdx         ; efi_early->call()
0x0eb      movq  %ds:0x10(%rax), %rax         ; efi_early->boot_services
0x0ef      je    $0x150
0x0f1      movq  %ds:0x48(%rax), %rdi         ; free_pool (64 bit)
0x0f5      xorl  %eax, %eax
0x0f7      callq *%rdx
...
0x150      movl  %ds:0x30(%rax), %edi         ; free_pool (32 bit)
0x153      jmp   $0x0f5

Size of eboot.o text section:
CONFIG_X86_32:                         6464 before, 6318 after
CONFIG_X86_64 && !CONFIG_EFI_MIXED:    7670 before, 7573 after
CONFIG_X86_64 &&  CONFIG_EFI_MIXED:    7670 before, 8319 after

Signed-off-by: Lukas Wunner 
Signed-off-by: Matt Fleming

x86/efi: Remove unused find_bits() function

2016-09-09T15:08:50+00:00

Left behind by commit fc37206427ce ("efi/libstub: Move Graphics Output
Protocol handling to generic code").

Signed-off-by: Lukas Wunner 
Cc: Ard Biesheuvel 
Signed-off-by: Matt Fleming

x86/efi: Initialize status to ensure garbage is not returned on small size

2016-09-09T15:08:44+00:00

Although very unlikey, if size is too small or zero, then we end up with
status not being set and returning garbage. Instead, initializing status to
EFI_INVALID_PARAMETER to indicate that size is invalid in the calls to
setup_uga32 and setup_uga64.

Signed-off-by: Colin Ian King 
Cc: "H. Peter Anvin" 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Signed-off-by: Matt Fleming

x86/efi: Use efi_exit_boot_services()

2016-09-05T11:40:16+00:00

The eboot code directly calls ExitBootServices.  This is inadvisable as the
UEFI spec details a complex set of errors, race conditions, and API
interactions that the caller of ExitBootServices must get correct.  The
eboot code attempts allocations after calling ExitBootSerives which is
not permitted per the spec.  Call the efi_exit_boot_services() helper
intead, which handles the allocation scenario properly.

Signed-off-by: Jeffrey Hugo 
Cc: Ard Biesheuvel 
Cc: Mark Rutland 
Cc: Leif Lindholm 
Cc: Ingo Molnar 
Cc: 
Signed-off-by: Matt Fleming

efi/libstub: Allocate headspace in efi_get_memory_map()

2016-09-05T11:18:17+00:00

efi_get_memory_map() allocates a buffer to store the memory map that it
retrieves.  This buffer may need to be reused by the client after
ExitBootServices() is called, at which point allocations are not longer
permitted.  To support this usecase, provide the allocated buffer size back
to the client, and allocate some additional headroom to account for any
reasonable growth in the map that is likely to happen between the call to
efi_get_memory_map() and the client reusing the buffer.

Signed-off-by: Jeffrey Hugo 
Cc: Ard Biesheuvel 
Cc: Mark Rutland 
Cc: Leif Lindholm 
Cc: Ingo Molnar 
Cc: 
Signed-off-by: Matt Fleming