| Message ID | 20240928155626.267348-1-cs.os.kernel@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | riscv: mm: check the SV39 rule | expand |
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index bfa2dea95354..82d112c02662 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -1387,6 +1387,12 @@ static void __init arch_reserve_crashkernel(void) void __init paging_init(void) { +#ifdef CONFIG_64BIT + BUILD_BUG_ON_MSG((VA_BITS == VA_BITS_SV39) && + (((FIXADDR_START & BIT(39)) >> 39) + != ((FIXADDR_START & BIT(38)) >> 38)), + "violate SV39 rule: bits[63..39] should be same as bit[38]"); +#endif setup_bootmem(); setup_vm_final();
SV39 rule: the address of bits[63..39] should be the same as bit[38], it is easy to violate if configure PAGE_OFFSET too small. for instance, PAGE_OFFSET=0xffffffc0_0000_0000, the FIXADDR_START will be the 0xfffffffb0_xxxx_xxxx, bit[39] == 0'b1, bit[38] == 0'b0, when access the FIXADDR, which cause the page fault. It's difficult to debug, check it when compile is necessary. Signed-off-by: Cheng Chao <cs.os.kernel@gmail.com> --- arch/riscv/mm/init.c | 6 ++++++ 1 file changed, 6 insertions(+)