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authorArd Biesheuvel <ardb@kernel.org>2024-10-09 18:04:40 +0200
committerJuergen Gross <jgross@suse.com>2024-10-29 17:23:28 +0100
commite8fbc0d9cab6c1ee6403f42c0991b0c1d5dbc092 (patch)
tree73a70e52d88a1aa2153e32e5199c305a99b6c56d /arch/x86/platform
parent81983758430957d9a5cb3333fe324fd70cf63e7e (diff)
x86/pvh: Call C code via the kernel virtual mapping
Calling C code via a different mapping than it was linked at is problematic, because the compiler assumes that RIP-relative and absolute symbol references are interchangeable. GCC in particular may use RIP-relative per-CPU variable references even when not using -fpic. So call xen_prepare_pvh() via its kernel virtual mapping on x86_64, so that those RIP-relative references produce the correct values. This matches the pre-existing behavior for i386, which also invokes xen_prepare_pvh() via the kernel virtual mapping before invoking startup_32 with paging disabled again. Fixes: 7243b93345f7 ("xen/pvh: Bootstrap PVH guest") Tested-by: Jason Andryuk <jason.andryuk@amd.com> Reviewed-by: Jason Andryuk <jason.andryuk@amd.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Message-ID: <20241009160438.3884381-8-ardb+git@google.com> Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'arch/x86/platform')
-rw-r--r--arch/x86/platform/pvh/head.S9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S
index 64fca49cd88f..ce4fd8d33da4 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -172,7 +172,14 @@ SYM_CODE_START_LOCAL(pvh_start_xen)
movq %rbp, %rbx
subq $_pa(pvh_start_xen), %rbx
movq %rbx, phys_base(%rip)
- call xen_prepare_pvh
+
+ /* Call xen_prepare_pvh() via the kernel virtual mapping */
+ leaq xen_prepare_pvh(%rip), %rax
+ subq phys_base(%rip), %rax
+ addq $__START_KERNEL_map, %rax
+ ANNOTATE_RETPOLINE_SAFE
+ call *%rax
+
/*
* Clear phys_base. __startup_64 will *add* to its value,
* so reset to 0.