On Mon, Nov 11, 2024 at 07:37:32AM -0700, Nathan Chancellor wrote:
From: Dan Carpenter dan.carpenter@linaro.org
commit 3d1c651272cf1df8aac7d9b6d92d836d27bed50f upstream.
Clang 19 prints a warning when we pass &th->guid to efi_pa_va_lookup():
drivers/acpi/prmt.c:156:29: error: passing 1-byte aligned argument to 4-byte aligned parameter 1 of 'efi_pa_va_lookup' may result in an unaligned pointer access [-Werror,-Walign-mismatch] 156 | (void *)efi_pa_va_lookup(&th->guid, handler_info->handler_address); | ^
The problem is that efi_pa_va_lookup() takes a efi_guid_t and &th->guid is a regular guid_t. The difference between the two types is the alignment. efi_guid_t is a typedef.
typedef guid_t efi_guid_t __aligned(__alignof__(u32));
It's possible that this a bug in Clang 19. Even though the alignment of &th->guid is not explicitly specified, it will still end up being aligned at 4 or 8 bytes.
Anyway, as Ard points out, it's cleaner to change guid to efi_guid_t type and that also makes the warning go away.
Fixes: 088984c8d54c ("ACPI: PRM: Find EFI_MEMORY_RUNTIME block for PRM handler and context") Reported-by: Linux Kernel Functional Testing lkft@linaro.org Suggested-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Dan Carpenter dan.carpenter@linaro.org Tested-by: Paul E. McKenney paulmck@kernel.org Acked-by: Ard Biesheuvel ardb@kernel.org Link: https://patch.msgid.link/3777d71b-9e19-45f4-be4e-17bf4fa7a834@stanley.mounta... [ rjw: Subject edit ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com [nathan: Fix conflicts due to lack of e38abdab441c] Signed-off-by: Nathan Chancellor nathan@kernel.org
This resolves the warning that Naresh reported, which breaks the build with CONFIG_WERROR=y:
https://lore.kernel.org/CA+G9fYtgOA-5y73G1YEixQ+OjmG=awBQjdKjK+b0qLNYvAAVpQ@... https://storage.tuxsuite.com/public/clangbuiltlinux/continuous-integration2/...
Now queued up,t hanks.
greg k-h