x86/hyperv: Use __naked attribute to fix stackless C function

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hv_crash_c_entry() is a C function that is entered without a stack,
and this is only allowed for functions that have the __naked attribute,
which informs the compiler that it must not emit the usual prologue and
epilogue or emit any other kind of instrumentation that relies on a
stack frame.

So split up the function, and set the __naked attribute on the initial
part that sets up the stack, GDT, IDT and other pieces that are needed
for ordinary C execution. Given that function calls are not permitted
either, use the existing long return coded in an asm() block to call the
second part of the function, which is an ordinary function that is
permitted to call other functions as usual.

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> # asm parts, not hv parts
Reviewed-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Acked-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: linux-hyperv@vger.kernel.org
Fixes: 94212d3461 ("x86/hyperv: Implement hypervisor RAM collection into vmcore")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

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Ard Biesheuvel 2026-03-02 17:45:31 +01:00 • committed by Wei Liu

parent edd20cb693

commit 3fde5281b8

1 changed files with 43 additions and 39 deletions

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arch/x86/hyperv/hv_crash.c

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