Re: [PATCH v3] ARM: imx: Fix suspend/resume crash with Clang CFI

[Sami Tolvanen]

On Thu, Jul 23, 2026 at 6:30 AM Yo'av Moshe <linux@xxxxxxxxxxxxx> wrote:
>
> On 2026-07-22 8:03 PM, Sami Tolvanen wrote:
> > As long as the C prototype for the assembly function matches the
> > function pointer type, the hashes should also match. Can you dump the
> > hash prefix from the OCRAM and compare it to the disassembly of the
> > call site?
> Here is what I saw when checking the disassembly in vmlinux:
>
> 1. Call site expected hash in pm-imx6.c: 0xA488EBFC
> 2. SYM_TYPED_FUNC_START hash prefix in suspend-imx6.S: 0xd4d4d4d4

What's the value for the __kcfi_typeid_imx6_suspend symbol in
vmlinux.o? I would expect the hash value to look a bit more random.

> It looks like because suspend-imx6.S is an assembly file, Clang emits
> the default assembly type ID (0xd4d4d4d4) for it, which doesn't match
> the C call site expectation (0xA488EBFC).

Clang doesn't actually emit type hashes for assembly functions.
SYM_TYPED_FUNC_START just adds a reference to the
__kcfi_typeid_<functionname> symbol that contains a hash calculated
for the C prototype.

Sami