x86/kexec: Push kjump return address even for non-kjump kexec

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The version of purgatory code shipped by kexec-tools attempts to look above
the top of its stack to find a return address for a kjump, even in a non-kjump
kexec.

After the commit in Fixes: the word above the stack might not be there,
leading to a fault (which is at least now caught by my exception-handling code
in kexec).

That commit fixed things for the actual kjump path, but no longer
"gratuitously" pushes the unused return address to the stack in the non-kjump
path. Put that *back* in the non-kjump path, to prevent purgatory from
crashing when trying to access it.

Fixes: 2cacf7f23a ("x86/kexec: Fix stack and handling of re-entry point for ::preserve_context")
Reported-by: Rohan Kakulawaram <rohanka@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Rohan Kakulawaram <rohanka@google.com>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/32d627134143ffd957891cb697138e839c623211.camel@infradead.org

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David Woodhouse 2026-04-28 21:59:52 +01:00 • committed by Borislav Petkov (AMD)

parent 5772f65352

commit 786a45757d

1 changed files with 8 additions and 0 deletions

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arch/x86/kernel/relocate_kernel_64.S

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