Unverified Commit f4b395e6 authored by Guo Ren's avatar Guo Ren Committed by Palmer Dabbelt
Browse files

riscv: compat: Add hw capability check for elf 



Detect hardware COMPAT (32bit U-mode) capability in rv64. If not
support COMPAT mode in hw, compat_elf_check_arch would return
false by compat_binfmt_elf.c

Add CLASS to enhance (compat_)elf_check_arch to distinguish
32BIT/64BIT elf.

Signed-off-by: default avatarGuo Ren <guoren@linux.alibaba.com>
Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
Tested-by: default avatarHeiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220405071314.3225832-16-guoren@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 87309e10

arch/riscv/include/asm/elf.h

+4 −2
Original line number Diff line number Diff line
@@ -33,9 +33,11 @@ 
/*

 * This is used to ensure we don't load something for the wrong architecture.

 */

#define elf_check_arch(x) ((x)->e_machine == EM_RISCV)

#define elf_check_arch(x) (((x)->e_machine == EM_RISCV) && \

			   ((x)->e_ident[EI_CLASS] == ELF_CLASS))



#define compat_elf_check_arch(x) ((x)->e_machine == EM_RISCV)

extern bool compat_elf_check_arch(Elf32_Ehdr *hdr);

#define compat_elf_check_arch	compat_elf_check_arch



#define CORE_DUMP_USE_REGSET

#define ELF_EXEC_PAGESIZE	(PAGE_SIZE)

arch/riscv/kernel/process.c

+28 −0
Original line number Diff line number Diff line
@@ -84,6 +84,34 @@ void show_regs(struct pt_regs *regs) 
		dump_backtrace(regs, NULL, KERN_DEFAULT);

}



#ifdef CONFIG_COMPAT

static bool compat_mode_supported __read_mostly;



bool compat_elf_check_arch(Elf32_Ehdr *hdr)

{

	return compat_mode_supported &&

	       hdr->e_machine == EM_RISCV &&

	       hdr->e_ident[EI_CLASS] == ELFCLASS32;

}



static int __init compat_mode_detect(void)

{

	unsigned long tmp = csr_read(CSR_STATUS);



	csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);

	compat_mode_supported =

			(csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;



	csr_write(CSR_STATUS, tmp);



	pr_info("riscv: ELF compat mode %s",

			compat_mode_supported ? "supported" : "failed");



	return 0;

}

early_initcall(compat_mode_detect);

#endif



void start_thread(struct pt_regs *regs, unsigned long pc,

	unsigned long sp)

{