arm64: stacktrace: Implement arch_bpf_stack_walk() for the BPF JIT

This will be used by bpf_throw() to unwind till the program marked as
exception boundary and run the callback with the stack of the main
program.

This is required for supporting BPF exceptions on ARM64.

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20240201125225.72796-2-puranjay12@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 7f88028a00c02c0e176af5ae7674ae606f5afd3a..66cffc5fc0be8cb933e5b9c8cfea68d30f6801a9 100644 (file)
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -7,6 +7,7 @@
 #include <linux/kernel.h>
 #include <linux/efi.h>
 #include <linux/export.h>
+#include <linux/filter.h>
 #include <linux/ftrace.h>
 #include <linux/kprobes.h>
 #include <linux/sched.h>
@@ -266,6 +267,31 @@ noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry,
        kunwind_stack_walk(arch_kunwind_consume_entry, &data, task, regs);
 }
 
+struct bpf_unwind_consume_entry_data {
+       bool (*consume_entry)(void *cookie, u64 ip, u64 sp, u64 fp);
+       void *cookie;
+};
+
+static bool
+arch_bpf_unwind_consume_entry(const struct kunwind_state *state, void *cookie)
+{
+       struct bpf_unwind_consume_entry_data *data = cookie;
+
+       return data->consume_entry(data->cookie, state->common.pc, 0,
+                                  state->common.fp);
+}
+
+noinline noinstr void arch_bpf_stack_walk(bool (*consume_entry)(void *cookie, u64 ip, u64 sp,
+                                                               u64 fp), void *cookie)
+{
+       struct bpf_unwind_consume_entry_data data = {
+               .consume_entry = consume_entry,
+               .cookie = cookie,
+       };
+
+       kunwind_stack_walk(arch_bpf_unwind_consume_entry, &data, current, NULL);
+}
+
 static bool dump_backtrace_entry(void *arg, unsigned long where)
 {
        char *loglvl = arg;