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* LoongArch: Add kdump supportYouling Tang2022-10-121-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds support for kdump. In kdump case the normal kernel will reserve a region for the crash kernel and jump there on panic. Arch-specific functions are added to allow for implementing a crash dump file interface, /proc/vmcore, which can be viewed as a ELF file. A user-space tool, such as kexec-tools, is responsible for allocating a separate region for the core's ELF header within the crash kdump kernel memory and filling it in when executing kexec_load(). Then, its location will be advertised to the crash dump kernel via a command line argument "elfcorehdr=", and the crash dump kernel will preserve this region for later use with arch_reserve_vmcore() at boot time. At the same time, the crash kdump kernel is also limited within the "crashkernel" area via a command line argument "mem=", so as not to destroy the original kernel dump data. In the crash dump kernel environment, /proc/vmcore is used to access the primary kernel's memory with copy_oldmem_page(). I tested kdump on LoongArch machines (Loongson-3A5000) and it works as expected (suggested crashkernel parameter is "crashkernel=512M@2560M"), you may test it by triggering a crash through /proc/sysrq-trigger: $ sudo kexec -p /boot/vmlinux-kdump --reuse-cmdline --append="nr_cpus=1" # echo c > /proc/sysrq-trigger Signed-off-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
* LoongArch: Use generic BUG() handlerYouling Tang2022-10-121-2/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Inspired by commit 9fb7410f955("arm64/BUG: Use BRK instruction for generic BUG traps"), do similar for LoongArch to use generic BUG() handler. This patch uses the BREAK software breakpoint instruction to generate a trap instead, similarly to most other arches, with the generic BUG code generating the dmesg boilerplate. This allows bug metadata to be moved to a separate table and reduces the amount of inline code at BUG() and WARN() sites. This also avoids clobbering any registers before they can be dumped. To mitigate the size of the bug table further, this patch makes use of the existing infrastructure for encoding addresses within the bug table as 32-bit relative pointers instead of absolute pointers. (Note: this limits the max kernel size to 2GB.) Before patch: [ 3018.338013] lkdtm: Performing direct entry BUG [ 3018.342445] Kernel bug detected[#5]: [ 3018.345992] CPU: 2 PID: 865 Comm: cat Tainted: G D 6.0.0-rc6+ #35 After patch: [ 125.585985] lkdtm: Performing direct entry BUG [ 125.590433] ------------[ cut here ]------------ [ 125.595020] kernel BUG at drivers/misc/lkdtm/bugs.c:78! [ 125.600211] Oops - BUG[#1]: [ 125.602980] CPU: 3 PID: 410 Comm: cat Not tainted 6.0.0-rc6+ #36 Out-of-line file/line data information obtained compared to before. Signed-off-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
* LoongArch: Refactor cache probe and flush methodsHuacai Chen2022-10-121-3/+0
| | | | | | | | | | | | Current cache probe and flush methods have some drawbacks: 1, Assume there are 3 cache levels and only 3 levels; 2, Assume L1 = I + D, L2 = V, L3 = S, V is exclusive, S is inclusive. However, the fact is I + D, I + D + V, I + D + S and I + D + V + S are all valid. So, refactor the cache probe and flush methods to adapt more types of cache hierarchy. Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
* LoongArch: Fix and cleanup csr_era handling in do_ri()Huacai Chen2022-09-291-13/+2
| | | | | | | | | | We don't emulate reserved instructions and just send a signal to the current process now. So we don't need to call compute_return_era() to add 4 (point to the next instruction) to csr_era in pt_regs. RA/ERA's backup/restore is cleaned up as well. Signed-off-by: Jun Yi <yijun@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
* LoongArch: Add prologue unwinder supportQing Zhang2022-08-121-0/+3
| | | | | | | | | | | | | | | | | It unwind the stack frame based on prologue code analyze. CONFIG_KALLSYMS is needed, at least the address and length of each function. Three stages when we do unwind, 1) unwind_start(), the prapare of unwinding, fill unwind_state. 2) unwind_done(), judge whether the unwind process is finished or not. 3) unwind_next_frame(), unwind the next frame. Dividing unwinder helps to add new unwinders in the future, e.g.: unwinder_frame, unwinder_orc, .etc. Signed-off-by: Qing Zhang <zhangqing@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
* LoongArch: Add guess unwinder supportQing Zhang2022-08-121-11/+10
| | | | | | | | | | | | | | | | | | | | Name "guess unwinder" comes from x86, it scans the stack and reports every kernel text address it finds. Unwinders can be used by dump_stack() and other stacktrace functions. Three stages when we do unwind, 1) unwind_start(), the prapare of unwinding, fill unwind_state. 2) unwind_done(), judge whether the unwind process is finished or not. 3) unwind_next_frame(), unwind the next frame. Add get_stack_info() to get stack info. At present we have irq stack and task stack. The next_sp is the key info between two types of stacks. Dividing unwinder helps to add new unwinders in the future. Signed-off-by: Qing Zhang <zhangqing@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
* LoongArch: Make compute_return_era() return voidTiezhu Yang2022-06-251-2/+1
| | | | | | | | compute_return_era() always returns 0, make it return void, and then no need to check its return value for its callers. Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
* LoongArch: Add Non-Uniform Memory Access (NUMA) supportHuacai Chen2022-06-031-2/+2
| | | | | | | | | | | | | Add Non-Uniform Memory Access (NUMA) support for LoongArch. LoongArch has 48-bit physical address, but the HyperTransport I/O bus only support 40-bit address, so we need a custom phys_to_dma() and dma_to_phys() to extract the 4-bit node id (bit 44~47) from Loongson-3's 48-bit physical address space and embed it into 40-bit. In the 40-bit dma address, node id offset can be read from the LS7A_DMA_CFG register. Reviewed-by: WANG Xuerui <git@xen0n.name> Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
* LoongArch: Add exception/interrupt handlingHuacai Chen2022-06-031-0/+725
Add the exception and interrupt handling machanism for basic LoongArch support. Reviewed-by: WANG Xuerui <git@xen0n.name> Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>