Messages in this thread | | | Date | Tue, 8 Nov 2022 00:40:19 +0300 | Subject | Re: [PATCH v1] riscv: fix reserved memory setup | From | Evgenii Shatokhin <> |
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Hi,
On 07.11.2022 18:15, Conor Dooley wrote: > «Внимание! Данное письмо от внешнего адресата!» > > Currently, RISC-V sets up reserved memory using the "early" copy of the > device tree. As a result, when trying to get a reserved memory region > using of_reserved_mem_lookup(), the pointer to reserved memory regions > is using the early, pre-virtual-memory address which causes a kernel > panic when trying to use the buffer's name: > > Unable to handle kernel paging request at virtual address 00000000401c31ac > Oops [#1] > Modules linked in: > CPU: 0 PID: 0 Comm: swapper Not tainted 6.0.0-rc1-00001-g0d9d6953d834 #1 > Hardware name: Microchip PolarFire-SoC Icicle Kit (DT) > epc : string+0x4a/0xea > ra : vsnprintf+0x1e4/0x336 > epc : ffffffff80335ea0 ra : ffffffff80338936 sp : ffffffff81203be0 > gp : ffffffff812e0a98 tp : ffffffff8120de40 t0 : 0000000000000000 > t1 : ffffffff81203e28 t2 : 7265736572203a46 s0 : ffffffff81203c20 > s1 : ffffffff81203e28 a0 : ffffffff81203d22 a1 : 0000000000000000 > a2 : ffffffff81203d08 a3 : 0000000081203d21 a4 : ffffffffffffffff > a5 : 00000000401c31ac a6 : ffff0a00ffffff04 a7 : ffffffffffffffff > s2 : ffffffff81203d08 s3 : ffffffff81203d00 s4 : 0000000000000008 > s5 : ffffffff000000ff s6 : 0000000000ffffff s7 : 00000000ffffff00 > s8 : ffffffff80d9821a s9 : ffffffff81203d22 s10: 0000000000000002 > s11: ffffffff80d9821c t3 : ffffffff812f3617 t4 : ffffffff812f3617 > t5 : ffffffff812f3618 t6 : ffffffff81203d08 > status: 0000000200000100 badaddr: 00000000401c31ac cause: 000000000000000d > [<ffffffff80338936>] vsnprintf+0x1e4/0x336 > [<ffffffff80055ae2>] vprintk_store+0xf6/0x344 > [<ffffffff80055d86>] vprintk_emit+0x56/0x192 > [<ffffffff80055ed8>] vprintk_default+0x16/0x1e > [<ffffffff800563d2>] vprintk+0x72/0x80 > [<ffffffff806813b2>] _printk+0x36/0x50 > [<ffffffff8068af48>] print_reserved_mem+0x1c/0x24 > [<ffffffff808057ec>] paging_init+0x528/0x5bc > [<ffffffff808031ae>] setup_arch+0xd0/0x592 > [<ffffffff8080070e>] start_kernel+0x82/0x73c > > early_init_fdt_scan_reserved_mem() takes no arguments as it operates on > initial_boot_params, which is populated by early_init_dt_verify(). On > RISC-V, early_init_dt_verify() is called twice. Once, directly, in > setup_arch() if CONFIG_BUILTIN_DTB is not enabled and once indirectly, > very early in the boot process, by parse_dtb() when it calls > early_init_dt_scan_nodes(). > > This first call uses dtb_early_va to set initial_boot_params, which is > not usable later in the boot process when > early_init_fdt_scan_reserved_mem() is called. On arm64 for example, the > corresponding call to early_init_dt_scan_nodes() uses fixmap addresses > and doesn't suffer the same fate.
Thank you for looking into this!
As I wrote earlier, I ran into this issue too, while working on a remoteproc driver for our RISC-V-based SoC.
The proposed patch fixes the bug for me and seems to have no problematic side-effects. So:
Tested-by: Evgenii Shatokhin <e.shatokhin@yadro.com>
> > Move early_init_fdt_scan_reserved_mem() further along the boot sequence, > after the direct call to early_init_dt_verify() in setup_arch() so that > the names use the correct virtual memory addresses. The above supposed > that CONFIG_BUILTIN_DTB was not set, but should work equally in the case > where it is - unflatted_and_copy_device_tree() also updates > initial_boot_params. > > Reported-by: Valentina Fernandez <valentina.fernandezalanis@microchip.com> > Reported-by: Evgenii Shatokhin <e.shatokhin@yadro.com> > Link: https://lore.kernel.org/linux-riscv/f8e67f82-103d-156c-deb0-d6d6e2756f5e@microchip.com/ > Fixes: 922b0375fc93 ("riscv: Fix memblock reservation for device tree blob") > Signed-off-by: Conor Dooley <conor.dooley@microchip.com> > --- > arch/riscv/kernel/setup.c | 1 + > arch/riscv/mm/init.c | 1 - > 2 files changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c > index ad76bb59b059..67ec1fadcfe2 100644 > --- a/arch/riscv/kernel/setup.c > +++ b/arch/riscv/kernel/setup.c > @@ -283,6 +283,7 @@ void __init setup_arch(char **cmdline_p) > else > pr_err("No DTB found in kernel mappings\n"); > #endif > + early_init_fdt_scan_reserved_mem(); > misc_mem_init(); > > init_resources(); > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index b56a0a75533f..50a1b6edd491 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -262,7 +262,6 @@ static void __init setup_bootmem(void) > memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va)); > } > > - early_init_fdt_scan_reserved_mem(); > dma_contiguous_reserve(dma32_phys_limit); > if (IS_ENABLED(CONFIG_64BIT)) > hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT); > -- > 2.38.0 >
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