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riscv: stacktrace: Fix missing the first frame 

When running kfence_test, I found some testcases failed like this:

 # test_out_of_bounds_read: EXPECTATION FAILED at mm/kfence/kfence_test.c:346
 Expected report_matches(&expect) to be true, but is false
 not ok 1 - test_out_of_bounds_read

The corresponding call-trace is:

 BUG: KFENCE: out-of-bounds read in kunit_try_run_case+0x38/0x84

 Out-of-bounds read at 0x(____ptrval____) (32B right of kfence-#10):
  kunit_try_run_case+0x38/0x84
  kunit_generic_run_threadfn_adapter+0x12/0x1e
  kthread+0xc8/0xde
  ret_from_exception+0x0/0xc

The kfence_test using the first frame of call trace to check whether the
testcase is succeed or not. Commit 6a00ef4493 ("riscv: eliminate
unreliable __builtin_frame_address(1)") skip first frame for all
case, which results the kfence_test failed. Indeed, we only need to skip
the first frame for case (task==NULL || task==current).

With this patch, the call-trace will be:

 BUG: KFENCE: out-of-bounds read in test_out_of_bounds_read+0x88/0x19e

 Out-of-bounds read at 0x(____ptrval____) (1B left of kfence-#7):
  test_out_of_bounds_read+0x88/0x19e
  kunit_try_run_case+0x38/0x84
  kunit_generic_run_threadfn_adapter+0x12/0x1e
  kthread+0xc8/0xde
  ret_from_exception+0x0/0xc

Fixes: 6a00ef4493 ("riscv: eliminate unreliable __builtin_frame_address(1)")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Tested-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20221207025038.1022045-1-liushixin2@huawei.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Liu Shixin 2022-12-07 10:50:38 +08:00 committed by Palmer Dabbelt
parent f0293cd1f4
commit cb80242cc6
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
1 changed files with 2 additions and 1 deletions
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3
arch/riscv/kernel/stacktrace.c
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@ -32,6 +32,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
fp = (unsigned long)__builtin_frame_address(0);
sp = current_stack_pointer;
pc = (unsigned long)walk_stackframe;
level = -1;
} else {
/* task blocked in __switch_to */
fp = task->thread.s[0];
@ -43,7 +44,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
unsigned long low, high;
struct stackframe *frame;
if (unlikely(!__kernel_text_address(pc) || (level++ >= 1 && !fn(arg, pc))))
if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
break;
/* Validate frame pointer */