Hi Guenter,
Le 4/16/21 à 2:51 PM, Guenter Roeck a écrit :
On Fri, Apr 09, 2021 at 02:14:58AM -0400, Alexandre Ghiti wrote:
This is a preparatory patch for relocatable kernel and sv48 support.
The kernel used to be linked at PAGE_OFFSET address therefore we could use
the linear mapping for the kernel mapping. But the relocated kernel base
address will be different from PAGE_OFFSET and since in the linear mapping,
two different virtual addresses cannot point to the same physical address,
the kernel mapping needs to lie outside the linear mapping so that we don't
have to copy it at the same physical offset.
The kernel mapping is moved to the last 2GB of the address space, BPF
is now always after the kernel and modules use the 2GB memory range right
before the kernel, so BPF and modules regions do not overlap. KASLR
implementation will simply have to move the kernel in the last 2GB range
and just take care of leaving enough space for BPF.
In addition, by moving the kernel to the end of the address space, both
sv39 and sv48 kernels will be exactly the same without needing to be
relocated at runtime.
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
In next-20210416, when booting a riscv32 image in qemu, this patch results in:
[ 0.000000] Linux version 5.12.0-rc7-next-20210416 (groeck@desktop) (riscv32-linux-gcc (GCC) 10.3.0, GNU ld (GNU Binutils) 2.36.1) #1 SMP Fri Apr 16 10:38:09 PDT 2021
[ 0.000000] OF: fdt: Ignoring memory block 0x80000000 - 0xa0000000
[ 0.000000] Machine model: riscv-virtio,qemu
[ 0.000000] earlycon: uart8250 at MMIO 0x10000000 (options '115200')
[ 0.000000] printk: bootconsole [uart8250] enabled
[ 0.000000] efi: UEFI not found.
[ 0.000000] Kernel panic - not syncing: init_resources: Failed to allocate 160 bytes
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.12.0-rc7-next-20210416 #1
[ 0.000000] Hardware name: riscv-virtio,qemu (DT)
[ 0.000000] Call Trace:
[ 0.000000] [<80005292>] walk_stackframe+0x0/0xce
[ 0.000000] [<809f4db8>] dump_backtrace+0x38/0x46
[ 0.000000] [<809f4dd4>] show_stack+0xe/0x16
[ 0.000000] [<809ff1d0>] dump_stack+0x92/0xc6
[ 0.000000] [<809f4fee>] panic+0x10a/0x2d8
[ 0.000000] [<80c02b24>] setup_arch+0x2a0/0x4ea
[ 0.000000] [<80c006b0>] start_kernel+0x90/0x628
[ 0.000000] ---[ end Kernel panic - not syncing: init_resources: Failed to allocate 160 bytes ]---
Reverting it fixes the problem. I understand that the version in -next is
different to this version of the patch, but I also tried v4 and it still
crashes with the same error message.
I completely neglected 32b kernel in this series, I fixed that here:
Thank you for testing and reporting,
Alex
Guenter
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