Using a function is flexible to represent ELF_HWCAP. So the kernel may
encode hwcap reflecting supported hardware features just at the moment of
the start of each program.
This will be helpful when we introduce prctl/sysctl interface to control
per-process availability of Vector extension in following patches.
Programs started with V disabled should see V masked off in theirs
ELF_HWCAP.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230605110724.21391-21-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
* 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 & ((1UL << RISCV_ISA_EXT_BASE) - 1))
+#define ELF_HWCAP riscv_get_elf_hwcap()
extern unsigned long elf_hwcap;
/*
#include <linux/jump_label.h>
+unsigned long riscv_get_elf_hwcap(void);
+
struct riscv_isa_ext_data {
/* Name of the extension displayed to userspace via /proc/cpuinfo */
char uprop[RISCV_ISA_EXT_NAME_LEN_MAX];
pr_info("riscv: ELF capabilities %s\n", print_str);
}
+unsigned long riscv_get_elf_hwcap(void)
+{
+ return (elf_hwcap & ((1UL << RISCV_ISA_EXT_BASE) - 1));
+}
+
#ifdef CONFIG_RISCV_ALTERNATIVE
/*
* Alternative patch sites consider 48 bits when determining when to patch