Author: jhb
Date: Tue Dec 8 17:57:18 2020
New Revision: 368454
URL: https://svnweb.freebsd.org/changeset/base/368454
Log:
Stack unwinding robustness fixes for RISC-V.
- Push the kstack_contains check down into unwind_frame() so that it
is honored by DDB and DTrace.
- Check that the trapframe for an exception frame is contained in the
traced thread's kernel stack for DDB traces.
Reviewed by: markj
Obtained from: CheriBSD
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D27357
Modified:
head/sys/cddl/dev/dtrace/riscv/dtrace_isa.c
head/sys/cddl/dev/fbt/fbt.c
head/sys/riscv/include/stack.h
head/sys/riscv/riscv/db_trace.c
head/sys/riscv/riscv/stack_machdep.c
head/sys/riscv/riscv/unwind.c
Modified: head/sys/cddl/dev/dtrace/riscv/dtrace_isa.c
==============================================================================
--- head/sys/cddl/dev/dtrace/riscv/dtrace_isa.c Tue Dec 8 17:44:34 2020
(r368453)
+++ head/sys/cddl/dev/dtrace/riscv/dtrace_isa.c Tue Dec 8 17:57:18 2020
(r368454)
@@ -90,7 +90,7 @@ dtrace_getpcstack(pc_t *pcstack, int pcstack_limit, in
state.pc = (uintptr_t)dtrace_getpcstack;
while (depth < pcstack_limit) {
- if (unwind_frame(&state))
+ if (!unwind_frame(curthread, &state))
break;
if (!INKERNEL(state.pc) || !INKERNEL(state.fp))
@@ -259,10 +259,10 @@ dtrace_getstackdepth(int aframes)
int scp_offset;
register_t sp;
int depth;
- int done;
+ bool done;
depth = 1;
- done = 0;
+ done = false;
__asm __volatile("mv %0, sp" : "=&r" (sp));
@@ -271,7 +271,7 @@ dtrace_getstackdepth(int aframes)
state.pc = (uintptr_t)dtrace_getstackdepth;
do {
- done = unwind_frame(&state);
+ done = !unwind_frame(curthread, &state);
if (!INKERNEL(state.pc) || !INKERNEL(state.fp))
break;
depth++;
Modified: head/sys/cddl/dev/fbt/fbt.c
==============================================================================
--- head/sys/cddl/dev/fbt/fbt.c Tue Dec 8 17:44:34 2020 (r368453)
+++ head/sys/cddl/dev/fbt/fbt.c Tue Dec 8 17:57:18 2020 (r368454)
@@ -137,6 +137,15 @@ fbt_excluded(const char *name)
return (1);
/*
+ * Stack unwinders may be called from probe context on some
+ * platforms.
+ */
+#if defined(__riscv)
+ if (strcmp(name, "unwind_frame") == 0)
+ return (1);
+#endif
+
+ /*
* When DTrace is built into the kernel we need to exclude
* the FBT functions from instrumentation.
*/
Modified: head/sys/riscv/include/stack.h
==============================================================================
--- head/sys/riscv/include/stack.h Tue Dec 8 17:44:34 2020
(r368453)
+++ head/sys/riscv/include/stack.h Tue Dec 8 17:57:18 2020
(r368454)
@@ -46,6 +46,6 @@ struct unwind_state {
uintptr_t pc;
};
-int unwind_frame(struct unwind_state *);
+bool unwind_frame(struct thread *, struct unwind_state *);
#endif /* !_MACHINE_STACK_H_ */
Modified: head/sys/riscv/riscv/db_trace.c
==============================================================================
--- head/sys/riscv/riscv/db_trace.c Tue Dec 8 17:44:34 2020
(r368453)
+++ head/sys/riscv/riscv/db_trace.c Tue Dec 8 17:57:18 2020
(r368454)
@@ -73,7 +73,7 @@ db_md_set_watchpoint(db_expr_t addr, db_expr_t size)
}
static void
-db_stack_trace_cmd(struct unwind_state *frame)
+db_stack_trace_cmd(struct thread *td, struct unwind_state *frame)
{
const char *name;
db_expr_t offset;
@@ -100,6 +100,11 @@ db_stack_trace_cmd(struct unwind_state *frame)
struct trapframe *tf;
tf = (struct trapframe *)(uintptr_t)frame->sp;
+ if (!kstack_contains(td, (vm_offset_t)tf,
+ sizeof(*tf))) {
+ db_printf("--- invalid trapframe %p\n", tf);
+ break;
+ }
if ((tf->tf_scause & SCAUSE_INTR) != 0)
db_printf("--- interrupt %ld\n",
@@ -119,7 +124,7 @@ db_stack_trace_cmd(struct unwind_state *frame)
if (strcmp(name, "fork_trampoline") == 0)
break;
- if (unwind_frame(frame) < 0)
+ if (!unwind_frame(td, frame))
break;
}
}
@@ -135,7 +140,7 @@ db_trace_thread(struct thread *thr, int count)
frame.sp = ctx->pcb_sp;
frame.fp = ctx->pcb_s[0];
frame.pc = ctx->pcb_ra;
- db_stack_trace_cmd(&frame);
+ db_stack_trace_cmd(thr, &frame);
return (0);
}
@@ -150,5 +155,5 @@ db_trace_self(void)
frame.sp = sp;
frame.fp = (uintptr_t)__builtin_frame_address(0);
frame.pc = (uintptr_t)db_trace_self;
- db_stack_trace_cmd(&frame);
+ db_stack_trace_cmd(curthread, &frame);
}
Modified: head/sys/riscv/riscv/stack_machdep.c
==============================================================================
--- head/sys/riscv/riscv/stack_machdep.c Tue Dec 8 17:44:34 2020
(r368453)
+++ head/sys/riscv/riscv/stack_machdep.c Tue Dec 8 17:57:18 2020
(r368454)
@@ -53,10 +53,8 @@ stack_capture(struct thread *td, struct stack *st, str
stack_zero(st);
while (1) {
- if (!kstack_contains(td, (vm_offset_t)frame->fp -
- (sizeof(uintptr_t) * 2), sizeof(uintptr_t) * 2))
+ if (!unwind_frame(td, frame))
break;
- unwind_frame(frame);
if (!INKERNEL((vm_offset_t)frame->pc))
break;
if (stack_put(st, frame->pc) == -1)
Modified: head/sys/riscv/riscv/unwind.c
==============================================================================
--- head/sys/riscv/riscv/unwind.c Tue Dec 8 17:44:34 2020
(r368453)
+++ head/sys/riscv/riscv/unwind.c Tue Dec 8 17:57:18 2020
(r368454)
@@ -35,23 +35,24 @@
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
+#include <sys/proc.h>
#include <machine/stack.h>
#include <machine/vmparam.h>
-int
-unwind_frame(struct unwind_state *frame)
+bool
+unwind_frame(struct thread *td, struct unwind_state *frame)
{
uintptr_t fp;
fp = frame->fp;
- if (!INKERNEL(fp))
- return (-1);
+ if (!kstack_contains(td, fp - sizeof(fp) * 2, sizeof(fp) * 2))
+ return (false);
frame->sp = fp;
frame->fp = ((uintptr_t *)fp)[-2];
frame->pc = ((uintptr_t *)fp)[-1] - 4;
- return (0);
+ return (true);
}
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