| 1 | /* SPDX-License-Identifier: GPL-2.0 */
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| 2 | /*
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| 3 | * PowerPC ELF notes.
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| 4 | *
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| 5 | * Copyright 2019, IBM Corporation
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| 6 | */
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| 7 |
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| 8 | |
| 9 | |
| 10 |
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| 11 | /*
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| 12 | * Ultravisor-capable bit (PowerNV only).
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| 13 | *
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| 14 | * Bit 0 indicates that the powerpc kernel binary knows how to run in an
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| 15 | * ultravisor-enabled system.
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| 16 | *
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| 17 | * In an ultravisor-enabled system, some machine resources are now controlled
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| 18 | * by the ultravisor. If the kernel is not ultravisor-capable, but it ends up
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| 19 | * being run on a machine with ultravisor, the kernel will probably crash
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| 20 | * trying to access ultravisor resources. For instance, it may crash in early
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| 21 | * boot trying to set the partition table entry 0.
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| 22 | *
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| 23 | * In an ultravisor-enabled system, a bootloader could warn the user or prevent
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| 24 | * the kernel from being run if the PowerPC ultravisor capability doesn't exist
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| 25 | * or the Ultravisor-capable bit is not set.
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| 26 | */
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| 27 | #ifdef CONFIG_PPC_POWERNV
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| 28 | #define PPCCAP_ULTRAVISOR_BIT (1 << 0)
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| 29 | #else
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| 30 | #define PPCCAP_ULTRAVISOR_BIT 0
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| 31 | #endif
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| 32 |
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| 33 | /*
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| 34 | * Add the PowerPC Capabilities in the binary ELF note. It is a bitmap that
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| 35 | * can be used to advertise kernel capabilities to userland.
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| 36 | */
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| 37 | #define PPC_CAPABILITIES_BITMAP (PPCCAP_ULTRAVISOR_BIT)
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| 38 |
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| 39 | ELFNOTE(PowerPC, PPC_ELFNOTE_CAPABILITIES,
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| 40 | .long PPC_CAPABILITIES_BITMAP)
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