diff options
| author | Claudio Carvalho <cclaudio@linux.ibm.com> | 2019-08-29 12:50:20 -0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-08-30 09:40:15 +1000 |
| commit | 70ed86f4de5bd74dd2d884dcd2f3275c4cfe665f (patch) | |
| tree | 65d5e98e0364848fb3fa3006dffb57ca0d0bdfc4 /arch/powerpc/kernel/note.S | |
| parent | a102f139aac54689eeb05883952742ae780159f3 (diff) | |
| download | linux-next-70ed86f4de5bd74dd2d884dcd2f3275c4cfe665f.tar.gz | |
powerpc: Add PowerPC Capabilities ELF note
Add the PowerPC name and the PPC_ELFNOTE_CAPABILITIES type in the
kernel binary ELF note. This type is a bitmap that can be used to
advertise kernel capabilities to userland.
This patch also defines PPCCAP_ULTRAVISOR_BIT as being the bit zero.
Suggested-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
[ maxiwell: Define the 'PowerPC' type in the elfnote.h ]
Signed-off-by: Maxiwell S. Garcia <maxiwell@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190829155021.2915-2-maxiwell@linux.ibm.com
Diffstat (limited to 'arch/powerpc/kernel/note.S')
| -rw-r--r-- | arch/powerpc/kernel/note.S | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/note.S b/arch/powerpc/kernel/note.S new file mode 100644 index 000000000000..bcdad15395dd --- /dev/null +++ b/arch/powerpc/kernel/note.S @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * PowerPC ELF notes. + * + * Copyright 2019, IBM Corporation + */ + +#include <linux/elfnote.h> +#include <asm/elfnote.h> + +/* + * Ultravisor-capable bit (PowerNV only). + * + * Bit 0 indicates that the powerpc kernel binary knows how to run in an + * ultravisor-enabled system. + * + * In an ultravisor-enabled system, some machine resources are now controlled + * by the ultravisor. If the kernel is not ultravisor-capable, but it ends up + * being run on a machine with ultravisor, the kernel will probably crash + * trying to access ultravisor resources. For instance, it may crash in early + * boot trying to set the partition table entry 0. + * + * In an ultravisor-enabled system, a bootloader could warn the user or prevent + * the kernel from being run if the PowerPC ultravisor capability doesn't exist + * or the Ultravisor-capable bit is not set. + */ +#ifdef CONFIG_PPC_POWERNV +#define PPCCAP_ULTRAVISOR_BIT (1 << 0) +#else +#define PPCCAP_ULTRAVISOR_BIT 0 +#endif + +/* + * Add the PowerPC Capabilities in the binary ELF note. It is a bitmap that + * can be used to advertise kernel capabilities to userland. + */ +#define PPC_CAPABILITIES_BITMAP (PPCCAP_ULTRAVISOR_BIT) + +ELFNOTE(PowerPC, PPC_ELFNOTE_CAPABILITIES, + .long PPC_CAPABILITIES_BITMAP) |