From: Conor Dooley conor.dooley@microchip.com
[ Upstream commit 50e63dd8ed92045eb70a72d7ec725488320fb68b ]
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.
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@mic... Fixes: 922b0375fc93 ("riscv: Fix memblock reservation for device tree blob") Signed-off-by: Conor Dooley conor.dooley@microchip.com Tested-by: Evgenii Shatokhin e.shatokhin@yadro.com Link: https://lore.kernel.org/r/20221107151524.3941467-1-conor.dooley@microchip.co... Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 57e1ab036edf..8e78a8ab6a34 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -96,6 +96,7 @@ 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();
#ifdef CONFIG_SWIOTLB diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index b6ab6a18dc1a..6c2f38aac544 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -208,7 +208,6 @@ 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); memblock_allow_resize(); memblock_dump_all();