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There are two possible code sections where the cpu_info macros can be
included: .code32 and .code64
Doing a `push %eax` while in a .code64 section will result in a compiler
error. This macro manually pushes the 32-bit register onto the stack so
we can share the code between 32 and 64 bit builds.
We also can't implicitly dereference per_cpu_segment_selector because
it's a 32-bit address. Trying to do this results in the following:
E: Invalid reloc type: 11
E: Illegal use of 32bit sign extended addressing at offset 0x1b2
If we load the address first, then dereference it, we can work around
the limitation.
With these fixes, 64-bit builds can now use CPU_INFO_V2.
BUG=b:179699789
TEST=Boot qemu 64 bit build with CPU_INFO_V2 and 4 CPUs. See AP init
work as expected.
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I4e72a808c9583bb2d0f697cbbd9cb9c0aa0ea2dc
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58232
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
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The push/pop of %ebx was only added because smm_stub saves the canary
value in it. Now that we no longer use cpu_info in smm, we no longer
need to save the register.
BUG=b:179699789
TEST=Boot guybrush to the OS
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I554dbe016db8b1c61246c8ffc7fa252b2542ba92
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58205
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
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We only ever start and execute threads on the BSP. By explicitly
checking to see if the CPU is the BSP we can remove the dependency on
cpu_info. With this change we can in theory enable threads in all
stages.
BUG=b:194391185, b:179699789
TEST=Boot guybrush to OS and verify coop multithreading still works
Suggested-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: Iea4622d52c36d529e100b7ea55f32c334acfdf3e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58199
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
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There is currently a fundamental flaw in the current cpu_info()
implementation. It assumes that current stack is CONFIG_STACK_SIZE
aligned. This assumption breaks down when performing SMM relocation.
The first step in performing SMM relocation is changing the SMBASE. This
is accomplished by installing the smmstub at 0x00038000, which is the
default SMM entry point. The stub is configured to set up a new stack
with the size of 1 KiB (CONFIG_SMM_STUB_STACK_SIZE), and an entry point
of smm_do_relocation located in RAMSTAGE RAM.
This means that when smm_do_relocation is executed, it is running in SMM
with a different sized stack. When cpu_info() gets called it will be
using CONFIG_STACK_SIZE to calculate the location of the cpu_info
struct. This results in reading random memory. Since cpu_info() has to
run in multiple environments, we can't use a compile time constant to
locate the cpu_info struct.
This CL introduces a new way of locating cpu_info. It uses a per-cpu
segment descriptor that points to a per-cpu segment that is allocated on
the stack. By using a segment descriptor to point to the per-cpu data,
we no longer need to calculate the location of the cpu_info struct. This
has the following advantages:
* Stacks no longer need to be CONFIG_STACK_SIZE aligned.
* Accessing an unconfigured segment will result in an exception. This
ensures no one can call cpu_info() from an unsupported environment.
* Segment selectors are cleared when entering SMM and restored when
leaving SMM.
* There is a 1:1 mapping between cpu and cpu_info. When using
COOP_MULTITASKING, a new cpu_info is currently allocated at the top of
each thread's stack. This no longer needs to happen.
This CL guards most of the code with CONFIG(CPU_INFO_V2). I did this so
reviewers can feel more comfortable knowing most of the CL is a no-op. I
would eventually like to remove most of the guards though.
This CL does not touch the LEGACY_SMP_INIT code path. I don't have any
way of testing it.
The %gs segment was chosen over the %fs segment because it's what the
linux kernel uses for per-cpu data in x86_64 mode.
BUG=b:194391185, b:179699789
TEST=Boot guybrush with CPU_INFO_V2 and verify BSP and APs have correct
%gs segment. Verify cpu_info looks sane. Verify booting to the OS
works correctly with COOP_MULTITASKING enabled.
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I79dce9597cb784acb39a96897fb3c2f2973bfd98
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57627
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Peers <epeers@google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
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This will help reduce duplication and make it easier to add new members
to the cpu_info struct.
BUG=b:194391185, b:179699789
TEST=Compare assembly of romstage and ramstage before and after
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I31f264f4bb8b605fa3cb3bfff0d9bf79224072aa
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57859
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
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