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Subject[PATCH-4.19-stable 0/2] Backport ENCODE_FRAME_POINTER hint
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On 4.19.93 the following warning was observed with CONFIG_FRAME_POINTER:
> WARNING: kernel stack frame pointer at 00000000bceb5183 in Coronavirus:3282 has bad value (null)
> unwind stack type:0 next_sp: (null) mask:0x2 graph_idx:0
> 000000009630aa47: ffffc9000126fdb0 (0xffffc9000126fdb0)
> 0000000020360f53: ffffffff81038e33 (__save_stack_trace+0xcb/0xee)
> 00000000675081f2: 0000000000000000 ...
> 0000000043198fe7: ffffc9000126c000 (0xffffc9000126c000)
> 0000000008a46231: ffffc90001270000 (0xffffc90001270000)
[..]

It turns to be missing %rbp hint was making frame pointer unwinder
a bit tipsy.
The observed is WARN_ONCE(), so it one time per boot, but imho, worth to
have in stable too.

Peter Zijlstra (2):
x86/stackframe: Move ENCODE_FRAME_POINTER to asm/frame.h
x86/stackframe, x86/ftrace: Add pt_regs frame annotations

arch/x86/entry/calling.h | 15 -----------
arch/x86/entry/entry_32.S | 16 ------------
arch/x86/include/asm/frame.h | 49 ++++++++++++++++++++++++++++++++++++
arch/x86/kernel/ftrace_32.S | 3 +++
arch/x86/kernel/ftrace_64.S | 3 +++
5 files changed, 55 insertions(+), 31 deletions(-)

--
2.25.0

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