From: Claudio Carvalho <cclaudio@xxxxxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Claudio Carvalho <cclaudio@xxxxxxxxxxxxx> [ maxiwell: Define the 'PowerPC' type in the elfnote.h ] Signed-off-by: Maxiwell S. Garcia <maxiwell@xxxxxxxxxxxxx> --- arch/powerpc/include/asm/elfnote.h | 24 ++++++++++++++++++ arch/powerpc/kernel/Makefile | 2 +- arch/powerpc/kernel/note.S | 40 ++++++++++++++++++++++++++++++ 3 files changed, 65 insertions(+), 1 deletion(-) create mode 100644 arch/powerpc/include/asm/elfnote.h create mode 100644 arch/powerpc/kernel/note.S diff --git a/arch/powerpc/include/asm/elfnote.h b/arch/powerpc/include/asm/elfnote.h new file mode 100644 index 000000000000..a201b6e9ae44 --- /dev/null +++ b/arch/powerpc/include/asm/elfnote.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * PowerPC ELF notes. + * + * Copyright 2019, IBM Corporation + */ + +#ifndef __ASM_POWERPC_ELFNOTE_H__ +#define __ASM_POWERPC_ELFNOTE_H__ + +/* + * These note types should live in a SHT_NOTE segment and have + * "PowerPC" in the name field. + */ + +/* + * The capabilities supported/required by this kernel (bitmap). + * + * This type uses a bitmap as "desc" field. Each bit is described + * in arch/powerpc/kernel/note.S + */ +#define PPC_ELFNOTE_CAPABILITIES 1 + +#endif /* __ASM_POWERPC_ELFNOTE_H__ */ diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 56dfa7a2a6f2..0fcd3045284f 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -52,7 +52,7 @@ obj-y := cputable.o ptrace.o syscalls.o \ of_platform.o prom_parse.o obj-$(CONFIG_PPC64) += setup_64.o sys_ppc32.o \ signal_64.o ptrace32.o \ - paca.o nvram_64.o firmware.o + paca.o nvram_64.o firmware.o note.o obj-$(CONFIG_VDSO32) += vdso32/ obj-$(CONFIG_PPC_WATCHDOG) += watchdog.o obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o 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) -- 2.20.1
