From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> kasan, arm64, scs, stacktrace: collect stack traces from Shadow Call Stack Currently, KASAN always uses the normal stack trace collection routines, which rely on the unwinder, when saving alloc and free stack traces. Instead of invoking the unwinder, collect the stack trace by copying frames from the Shadow Call Stack whenever it is enabled. This reduces boot time by 30% for all KASAN modes when Shadow Call Stack is enabled. Stack staces are collected from the Shadow Call Stack via a new stack_trace_save_shadow() interface. Note that the frame of the interrupted function is not included into the stack trace, as it is not yet saved on the SCS when an interrupt happens. --- To deal with this last thing, we could save the interrupted frame address in another per-CPU variable. I'll look into implementing this for v3. I decided to postpone the changes to stack depot that avoid copying frames twice until a planned upcoming update for stack depot. Changes v1->v2: - Provide a kernel-wide stack_trace_save_shadow() interface for collecting stack traces from shadow stack. - Use ptrauth_strip_insn_pac() and READ_ONCE_NOCHECK, see the comments. - Get SCS pointer from x18, as per-task value is meant to save the SCS value on CPU switches. - Collect stack frames from SDEI and IRQ contexts. Andrey Konovalov (4): stacktrace: add interface based on shadow call stack arm64, scs: save scs_sp values per-cpu when switching stacks arm64: implement stack_trace_save_shadow kasan: use stack_trace_save_shadow arch/Kconfig | 6 +++ arch/arm64/Kconfig | 1 + arch/arm64/include/asm/assembler.h | 12 +++++ arch/arm64/include/asm/scs.h | 13 ++++- arch/arm64/kernel/entry.S | 28 ++++++++-- arch/arm64/kernel/irq.c | 4 +- arch/arm64/kernel/sdei.c | 5 +- arch/arm64/kernel/stacktrace.c | 83 ++++++++++++++++++++++++++++++ include/linux/stacktrace.h | 15 ++++++ kernel/stacktrace.c | 21 ++++++++ mm/kasan/common.c | 9 ++-- 11 files changed, 183 insertions(+), 14 deletions(-) -- 2.25.1
