Unverified Commit 2350bd19 authored by Palmer Dabbelt's avatar Palmer Dabbelt
Browse files

RISC-V: Only provide the single-letter extensions in HWCAP 



The recent refactoring led to us leaking some HWCAP bits to userspace
that didn't make much sense.  With any luck we'll have a better scheme
soon, but for now just mask off those bits to avoid polluting userspace.

Acked-by: default avatarConor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230202233832.11036-1-palmer@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent b49f7006

arch/riscv/include/asm/elf.h

+6 −4
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <asm/auxvec.h>

#include <asm/byteorder.h>

#include <asm/cacheinfo.h>

#include <asm/hwcap.h>



/*

 * These are used to set parameters in the core dumps.
@@ -59,12 +60,13 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr); 
#define STACK_RND_MASK		(0x3ffff >> (PAGE_SHIFT - 12))

#endif

#endif



/*

 * This yields a mask that user programs can use to figure out what

 * instruction set this CPU supports.  This could be done in user space,

 * but it's not easy, and we've already done it here.

 * Provides information on the availiable set of ISA extensions to userspace,

 * via a bitmap that coorespends to each single-letter ISA extension.  This is

 * essentially defunct, but will remain for compatibility with userspace.

 */

#define ELF_HWCAP	(elf_hwcap)

#define ELF_HWCAP	(elf_hwcap & ((1UL << RISCV_ISA_EXT_BASE) - 1))

extern unsigned long elf_hwcap;



/*

arch/riscv/include/asm/hwcap.h

+0 −8
Original line number Diff line number Diff line
@@ -52,18 +52,10 @@ 


#include <linux/jump_label.h>



/*

 * This yields a mask that user programs can use to figure out what

 * instruction set this cpu supports.

 */

#define ELF_HWCAP		(elf_hwcap)



enum {

	CAP_HWCAP = 1,

};



extern unsigned long elf_hwcap;



struct riscv_isa_ext_data {

	/* Name of the extension displayed to userspace via /proc/cpuinfo */

	char uprop[RISCV_ISA_EXT_NAME_LEN_MAX];