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riscv: compat: Add hw capability check for elf

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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: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220405071314.3225832-16-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Guo Ren 2022-04-05 15:13:09 +08:00 committed by Palmer Dabbelt
parent 87309e1082
commit f4b395e6f1
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GPG key ID: 2E1319F35FBB1889
2 changed files with 32 additions and 2 deletions
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6
arch/riscv/include/asm/elf.h
View file

@ -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)

28
arch/riscv/kernel/process.c
View file

@ -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)
{