• Conor Dooley's avatar
    riscv: fix reserved memory setup · 50e63dd8
    Conor Dooley authored
    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: default avatarValentina Fernandez <valentina.fernandezalanis@microchip.com>
    Reported-by: default avatarEvgenii Shatokhin <e.shatokhin@yadro.com>
    Link: https://lore.kernel.org/linux-riscv/f8e67f82-103d-156c-deb0-d6d6e2756f5e@microchip.com/
    Fixes: 922b0375 ("riscv: Fix memblock reservation for device tree blob")
    Signed-off-by: default avatarConor Dooley <conor.dooley@microchip.com>
    Tested-by: default avatarEvgenii Shatokhin <e.shatokhin@yadro.com>
    Link: https://lore.kernel.org/r/20221107151524.3941467-1-conor.dooley@microchip.comSigned-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
    50e63dd8
init.c 36 KB