3 Commits

Author	SHA1	Message	Date
Alexandre Ghiti	f7ae02333d	riscv: Move KASAN mapping next to the kernel mapping ... Now that KASAN_SHADOW_OFFSET is defined at compile time as a config, this value must remain constant whatever the size of the virtual address space, which is only possible by pushing this region at the end of the address space next to the kernel mapping. Signed-off-by: Alexandre Ghiti <alexandre.ghiti@canonical.com> Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>	2022-01-19 17:54:04 -08:00
Jisheng Zhang	3a02764c37	riscv: Ensure BPF_JIT_REGION_START aligned with PMD size ... Andreas reported commit fc8504765e ("riscv: bpf: Avoid breaking W^X") breaks booting with one kind of defconfig, I reproduced a kernel panic with the defconfig: [ 0.138553] Unable to handle kernel paging request at virtual address ffffffff81201220 [ 0.139159] Oops [#1] [ 0.139303] Modules linked in: [ 0.139601] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc5-default+ #1 [ 0.139934] Hardware name: riscv-virtio,qemu (DT) [ 0.140193] epc : __memset+0xc4/0xfc [ 0.140416] ra : skb_flow_dissector_init+0x1e/0x82 [ 0.140609] epc : ffffffff8029806c ra : ffffffff8033be78 sp : ffffffe001647da0 [ 0.140878] gp : ffffffff81134b08 tp : ffffffe001654380 t0 : ffffffff81201158 [ 0.141156] t1 : 0000000000000002 t2 : 0000000000000154 s0 : ffffffe001647dd0 [ 0.141424] s1 : ffffffff80a43250 a0 : ffffffff81201220 a1 : 0000000000000000 [ 0.141654] a2 : 000000000000003c a3 : ffffffff81201258 a4 : 0000000000000064 [ 0.141893] a5 : ffffffff8029806c a6 : 0000000000000040 a7 : ffffffffffffffff [ 0.142126] s2 : ffffffff81201220 s3 : 0000000000000009 s4 : ffffffff81135088 [ 0.142353] s5 : ffffffff81135038 s6 : ffffffff8080ce80 s7 : ffffffff80800438 [ 0.142584] s8 : ffffffff80bc6578 s9 : 0000000000000008 s10: ffffffff806000ac [ 0.142810] s11: 0000000000000000 t3 : fffffffffffffffc t4 : 0000000000000000 [ 0.143042] t5 : 0000000000000155 t6 : 00000000000003ff [ 0.143220] status: 0000000000000120 badaddr: ffffffff81201220 cause: 000000000000000f [ 0.143560] [<ffffffff8029806c>] __memset+0xc4/0xfc [ 0.143859] [<ffffffff8061e984>] init_default_flow_dissectors+0x22/0x60 [ 0.144092] [<ffffffff800010fc>] do_one_initcall+0x3e/0x168 [ 0.144278] [<ffffffff80600df0>] kernel_init_freeable+0x1c8/0x224 [ 0.144479] [<ffffffff804868a8>] kernel_init+0x12/0x110 [ 0.144658] [<ffffffff800022de>] ret_from_exception+0x0/0xc [ 0.145124] ---[ end trace f1e9643daa46d591 ]--- After some investigation, I think I found the root cause: commit 2bfc6cd81b ("move kernel mapping outside of linear mapping") moves BPF JIT region after the kernel: | #define BPF_JIT_REGION_START PFN_ALIGN((unsigned long)&_end) The &_end is unlikely aligned with PMD size, so the front bpf jit region sits with part of kernel .data section in one PMD size mapping. But kernel is mapped in PMD SIZE, when bpf_jit_binary_lock_ro() is called to make the first bpf jit prog ROX, we will make part of kernel .data section RO too, so when we write to, for example memset the .data section, MMU will trigger a store page fault. To fix the issue, we need to ensure the BPF JIT region is PMD size aligned. This patch acchieve this goal by restoring the BPF JIT region to original position, I.E the 128MB before kernel .text section. The modification to kasan_init.c is inspired by Alexandre. Fixes: fc8504765e ("riscv: bpf: Avoid breaking W^X") Reported-by: Andreas Schwab <schwab@linux-m68k.org> Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>	2021-06-18 21:10:05 -07:00
Alexandre Ghiti	2a433cf8f3	Documentation: riscv: Add documentation that describes the VM layout ... This new document presents the RISC-V virtual memory layout and is based one the x86 one: it describes the different limits of the different regions of the virtual address space. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>	2021-04-26 08:25:05 -07:00