From 314b781706e337b8cbde98cfefd3975863e032f2 Mon Sep 17 00:00:00 2001 From: Jisheng Zhang Date: Fri, 18 Jun 2021 22:01:36 +0800 Subject: riscv: kasan: Fix MODULES_VADDR evaluation due to local variables' name commit 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear mapping") makes use of MODULES_VADDR to populate kernel, BPF, modules mapping. Currently, MODULES_VADDR is defined as below for RV64: | #define MODULES_VADDR (PFN_ALIGN((unsigned long)&_end) - SZ_2G) But kasan_init() has two local variables which are also named as _start, _end, so MODULES_VADDR is evaluated with the local variable _end rather than the global "_end" as we expected. Fix this issue by renaming the two local variables. Fixes: 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear mapping") Signed-off-by: Jisheng Zhang Signed-off-by: Palmer Dabbelt --- arch/riscv/mm/kasan_init.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch/riscv/mm') diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c index 9daacae93e33..a0d9e4ace331 100644 --- a/arch/riscv/mm/kasan_init.c +++ b/arch/riscv/mm/kasan_init.c @@ -169,7 +169,7 @@ static void __init kasan_shallow_populate(void *start, void *end) void __init kasan_init(void) { - phys_addr_t _start, _end; + phys_addr_t p_start, p_end; u64 i; /* @@ -189,9 +189,9 @@ void __init kasan_init(void) (void *)kasan_mem_to_shadow((void *)VMALLOC_END)); /* Populate the linear mapping */ - for_each_mem_range(i, &_start, &_end) { - void *start = (void *)__va(_start); - void *end = (void *)__va(_end); + for_each_mem_range(i, &p_start, &p_end) { + void *start = (void *)__va(p_start); + void *end = (void *)__va(p_end); if (start >= end) break; -- cgit v1.2.3 From 3a02764c372c50ff7917fde5c6961f6cdb81d9d5 Mon Sep 17 00:00:00 2001 From: Jisheng Zhang Date: Fri, 18 Jun 2021 22:09:13 +0800 Subject: riscv: Ensure BPF_JIT_REGION_START aligned with PMD size Andreas reported commit fc8504765ec5 ("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] [] __memset+0xc4/0xfc [ 0.143859] [] init_default_flow_dissectors+0x22/0x60 [ 0.144092] [] do_one_initcall+0x3e/0x168 [ 0.144278] [] kernel_init_freeable+0x1c8/0x224 [ 0.144479] [] kernel_init+0x12/0x110 [ 0.144658] [] ret_from_exception+0x0/0xc [ 0.145124] ---[ end trace f1e9643daa46d591 ]--- After some investigation, I think I found the root cause: commit 2bfc6cd81bd ("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: fc8504765ec5 ("riscv: bpf: Avoid breaking W^X") Reported-by: Andreas Schwab Signed-off-by: Jisheng Zhang Signed-off-by: Palmer Dabbelt --- arch/riscv/mm/kasan_init.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/riscv/mm') diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c index a0d9e4ace331..d7189c8714a9 100644 --- a/arch/riscv/mm/kasan_init.c +++ b/arch/riscv/mm/kasan_init.c @@ -201,7 +201,7 @@ void __init kasan_init(void) /* Populate kernel, BPF, modules mapping */ kasan_populate(kasan_mem_to_shadow((const void *)MODULES_VADDR), - kasan_mem_to_shadow((const void *)BPF_JIT_REGION_END)); + kasan_mem_to_shadow((const void *)MODULES_VADDR + SZ_2G)); for (i = 0; i < PTRS_PER_PTE; i++) set_pte(&kasan_early_shadow_pte[i], -- cgit v1.2.3