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KVM: arm64: Generate hyp relocation data

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Add a post-processing step to compilation of KVM nVHE hyp code which
calls a custom host tool (gen-hyprel) on the partially linked object
file (hyp sections' names prefixed).

The tool lists all R_AARCH64_ABS64 data relocations targeting hyp
sections and generates an assembly file that will form a new section
.hyp.reloc in the kernel binary. The new section contains an array of
32-bit offsets to the positions targeted by these relocations.

Since these addresses of those positions will not be determined until
linking of `vmlinux`, each 32-bit entry carries a R_AARCH64_PREL32
relocation with addend <section_base_sym> + <r_offset>. The linker of
`vmlinux` will therefore fill the slot accordingly.

This relocation data will be used at runtime to convert the kernel VAs
at those positions to hyp VAs.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210105180541.65031-5-dbrazdil@google.com
This commit is contained in:
David Brazdil
2021-01-05 18:05:37 +00:00
committed by Marc Zyngier
parent f7a4825d95
commit 8c49b5d43d
4 changed files with 451 additions and 3 deletions
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11
arch/arm64/kernel/vmlinux.lds.S
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@@ -43,10 +43,19 @@ jiffies = jiffies_64;
HYP_SECTION_NAME(.data..percpu) : { \
*(HYP_SECTION_NAME(.data..percpu)) \
}
#define HYPERVISOR_RELOC_SECTION \
.hyp.reloc : ALIGN(4) { \
__hyp_reloc_begin = .; \
*(.hyp.reloc) \
__hyp_reloc_end = .; \
}
#else /* CONFIG_KVM */
#define HYPERVISOR_EXTABLE
#define HYPERVISOR_DATA_SECTIONS
#define HYPERVISOR_PERCPU_SECTION
#define HYPERVISOR_RELOC_SECTION
#endif
#define HYPERVISOR_TEXT \
@@ -217,6 +226,8 @@ SECTIONS
PERCPU_SECTION(L1_CACHE_BYTES)
HYPERVISOR_PERCPU_SECTION
HYPERVISOR_RELOC_SECTION
.rela.dyn : ALIGN(8) {
*(.rela .rela*)
}