Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 22 Dec 2023 19:36:39 -0800 | From | Charlie Jenkins <> | Subject | Re: [PATCH V3 1/4] riscv: mm: Fixup compat mode boot failure |
| |
On Sat, Dec 23, 2023 at 11:07:29AM +0800, Guo Ren wrote: > On Sat, Dec 23, 2023 at 10:58 AM Leonardo Bras <leobras@redhat.com> wrote: > > > > On Fri, Dec 22, 2023 at 06:57:00AM -0500, guoren@kernel.org wrote: > > > From: Guo Ren <guoren@linux.alibaba.com> > > > > > > In COMPAT mode, the STACK_TOP is DEFAULT_MAP_WINDOW (0x80000000), but > > > the TASK_SIZE is 0x7fff000. When the user stack is upon 0x7fff000, it > > > will cause a user segment fault. Sometimes, it would cause boot > > > failure when the whole rootfs is rv32. > > > > > > Freeing unused kernel image (initmem) memory: 2236K > > > Run /sbin/init as init process > > > Starting init: /sbin/init exists but couldn't execute it (error -14) > > > Run /etc/init as init process > > > ... > > > > > > Increase the TASK_SIZE to cover STACK_TOP. > > > > > > Cc: stable@vger.kernel.org > > > Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57") > > > Signed-off-by: Guo Ren <guoren@linux.alibaba.com> > > > Signed-off-by: Guo Ren <guoren@kernel.org> > > > --- > > > arch/riscv/include/asm/pgtable.h | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > > > index ab00235b018f..74ffb2178f54 100644 > > > --- a/arch/riscv/include/asm/pgtable.h > > > +++ b/arch/riscv/include/asm/pgtable.h > > > @@ -881,7 +881,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte) > > > #define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2) > > > > > > #ifdef CONFIG_COMPAT > > > -#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE) > > > +#define TASK_SIZE_32 (_AC(0x80000000, UL)) > > > #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \ > > > TASK_SIZE_32 : TASK_SIZE_64) > > > #else > > > -- > > > 2.40.1 > > > > > > > I am not really involved in the issue this is solving, so I have no > > technical opinion on the solution. > > > > IIUC there should always be (TASK_SIZE >= STACK_TOP), so by itself this > > is fixing an issue. > > > > I have reviewed the code and it does exactly as stated into the commit > > message, so FWIW: > > Reviewed-by: Leonardo Bras <leobras@redhat.com> > Thx, > > I found this problem because it can't boot my rv32 buildroot-rootfs in > v6.6. But it's okay in v6.5. So I used git bisect and found commit: > add2cc6b6515 ("RISC-V: mm: Restrict address space for > sv39,sv48,sv57"), which caused that. > > Ping Charlie, I hope it can be fixed in the v6.6 long-term version.
I have looked at this more I do agree that this change makes sense. I was thinking that it was valid to have STACK_TOP that was greater than TASK_SIZE but I am no longer convinced that is true. Thank you for looking into this.
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
> > > > > > > -- > Best Regards > Guo Ren
| ![\](/images/icornerr.gif) |