From 95bb5b617beec0275bcc47b68796b34852fe4ecb Mon Sep 17 00:00:00 2001 From: Enze Li Date: Wed, 6 Sep 2023 22:54:16 +0800 Subject: [PATCH] LoongArch: Get partial stack information when providing regs parameter Currently, arch_stack_walk() can only get the full stack information including NMI. This is because the implementation of arch_stack_walk() is forced to ignore the information passed by the regs parameter and use the current stack information instead. For some detection systems like KFENCE, only partial stack information is needed. In particular, the stack frame where the interrupt occurred. To support KFENCE, this patch modifies the implementation of the arch_stack_walk() function so that if this function is called with the regs argument passed, it retains all the stack information in regs and uses it to provide accurate information. Before this patch: [ 1.531195 ] ================================================================== [ 1.531442 ] BUG: KFENCE: out-of-bounds read in stack_trace_save_regs+0x48/0x6c [ 1.531442 ] [ 1.531900 ] Out-of-bounds read at 0xffff800012267fff (1B left of kfence-#12): [ 1.532046 ] stack_trace_save_regs+0x48/0x6c [ 1.532169 ] kfence_report_error+0xa4/0x528 [ 1.532276 ] kfence_handle_page_fault+0x124/0x270 [ 1.532388 ] no_context+0x50/0x94 [ 1.532453 ] do_page_fault+0x1a8/0x36c [ 1.532524 ] tlb_do_page_fault_0+0x118/0x1b4 [ 1.532623 ] test_out_of_bounds_read+0xa0/0x1d8 [ 1.532745 ] kunit_generic_run_threadfn_adapter+0x1c/0x28 [ 1.532854 ] kthread+0x124/0x130 [ 1.532922 ] ret_from_kernel_thread+0xc/0xa4 After this patch: [ 1.320220 ] ================================================================== [ 1.320401 ] BUG: KFENCE: out-of-bounds read in test_out_of_bounds_read+0xa8/0x1d8 [ 1.320401 ] [ 1.320898 ] Out-of-bounds read at 0xffff800012257fff (1B left of kfence-#10): [ 1.321134 ] test_out_of_bounds_read+0xa8/0x1d8 [ 1.321264 ] kunit_generic_run_threadfn_adapter+0x1c/0x28 [ 1.321392 ] kthread+0x124/0x130 [ 1.321459 ] ret_from_kernel_thread+0xc/0xa4 Suggested-by: Jinyang He Signed-off-by: Enze Li Signed-off-by: Huacai Chen --- arch/loongarch/kernel/stacktrace.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c index 2463d2fea21f..92270f14db94 100644 --- a/arch/loongarch/kernel/stacktrace.c +++ b/arch/loongarch/kernel/stacktrace.c @@ -18,17 +18,19 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, struct pt_regs dummyregs; struct unwind_state state; - regs = &dummyregs; + if (!regs) { + regs = &dummyregs; - if (task == current) { - regs->regs[3] = (unsigned long)__builtin_frame_address(0); - regs->csr_era = (unsigned long)__builtin_return_address(0); - } else { - regs->regs[3] = thread_saved_fp(task); - regs->csr_era = thread_saved_ra(task); + if (task == current) { + regs->regs[3] = (unsigned long)__builtin_frame_address(0); + regs->csr_era = (unsigned long)__builtin_return_address(0); + } else { + regs->regs[3] = thread_saved_fp(task); + regs->csr_era = thread_saved_ra(task); + } + regs->regs[1] = 0; } - regs->regs[1] = 0; for (unwind_start(&state, task, regs); !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) { addr = unwind_get_return_address(&state);