On Wed, Mar 08, 2023 at 05:12:26AM +0100, Heinrich Schuchardt wrote:
Hello Ilias, hello Tom,
Tom tried to run qemu_arm_defconfig with CONFIG_LTO=y in gitlab. This failed as shown in protocol https://source.denx.de/u-boot/u-boot/-/jobs/589913/raw
Executing 'HII database protocols' test_hii_database_new_package_list: data abort pc : [<7ff39b98>] lr : [<7ff87328>] reloc pc : [<00000b98>] lr : [<0004e328>] sp : 7edf8cc0 ip : 0000000c fp : 7ffe60ec r10: 00000000 r9 : 7eef8eb0 r8 : 7ffe0d02 r7 : 00000000 r6 : 7ef0f8c8 r5 : 7ffe0cf0 r4 : 7ffe0cb4 r3 : 7ffe0cef r2 : 00000000 r1 : ffffffff r0 : 00000000 Flags: nzcv IRQs off FIQs off Mode SVC_32 Code: e2403002 e3a00000 e1500001 012fff1e (e1f320b2) UEFI image [0x00000000:0xffffffff] '/\selftest' Resetting CPU ..
Debugging shows:
efi_hii_sibt_string_ucs2_block_next() calls u16_strnlen() for an unaligned u16 string. Here "ldrh r2, [r3, #2]!" is executed for unaligned r3. This should be allowable for SCTLR.A = 0.
When the crash occurs SCRLR has value 0xc5187f. SCTLR.A is bit 1 with value 1.
The implementation of allow_unaligned() in arch/arm/cpu/armv7 /sctlr.S should have set the flag to 0. arch/arm/cpu/armv7/sctlr.S is compiled (as demonstrated by adding #error to the code).
If I remove the weak implementation of allow_unaligned() in lib/efi_loader/efi_setup.c, the error does not occur.
Shouldn't building with LTO ignore the weak implementation?
If I add a printf() statement to the weak implemenation, the printf() command is not executed but
SCTLR 0xc5187d, SCTLR.A=0
The test passes as unaligned access is allowable.
I was building inside the Docker image with the GCC downloaded by buildman (gcc-12.2.0-nolibc/arm-linux-gnueabi).
To me this looks like a compiler issue.
Interesting, yes. It seems like it shouldn't be too hard to come up with a condensed example where the assembly function isn't used but instead the weak C function is.
And as a work-around, re-doing the code so that path_to_uefi() just checks for ARM && !ARM64 before calling allow_unaligned() and not doing the weak function trick should also be fine.