ERROR: start_text address is c000000000009400, should be c000000000008000

[nathanchance]

After llvm/llvm-project@3733463:

$ make -skj"$(nproc)" ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- LLVM=1 O=out distclean powernv_defconfig zImage.epapr
ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: kernel/built-in.a(printk/printk.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: lib/lib.a(dump_stack.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: lib/lib.a(string.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: drivers/built-in.a(base/core.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: net/built-in.a(core/dev.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: address (0xc000000000009314) of section .text is not a multiple of alignment (256)
ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: kernel/built-in.a(printk/printk.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: lib/lib.a(dump_stack.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: lib/lib.a(string.o):(.text.unlikely.) is being placed in '.text.unlikely.'                                                                                                                                                                                  ld.lld: warning: drivers/built-in.a(base/core.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: net/built-in.a(core/dev.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: address (0xc000000000009314) of section .text is not a multiple of alignment (256)
ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.'                                                                                                                                                                           ld.lld: warning: kernel/built-in.a(printk/printk.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: lib/lib.a(dump_stack.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: lib/lib.a(string.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: drivers/built-in.a(base/core.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: net/built-in.a(core/dev.o):(.text.unlikely.) is being placed in '.text.unlikely.'
ld.lld: warning: address (0xc000000000009314) of section .text is not a multiple of alignment (256)
ERROR: start_text address is c000000000009400, should be c000000000008000                                                                                                                                                                                                    ERROR: try to enable LD_HEAD_STUB_CATCH config option
ERROR: see comments in arch/powerpc/tools/head_check.sh
make[3]: *** [../arch/powerpc/Makefile.postlink:31: vmlinux] Error 1

$ git bisect log
# bad: [d4ec3346b1baf31819d20a8950ced8be8f66a408] [lld-macho][nfc] Refactor to accommodate paired relocs
# good: [70b0d152435018475516d544fd0361076533f921] [gn build] Port b9c77542e23
git bisect start 'd4ec3346b1baf31819d20a8950ced8be8f66a408' '70b0d152435018475516d544fd0361076533f921'
# good: [39584ae5b5cbc817d19499b003d4eaba259c31b5] [Debugify] Support checking Machine IR debug info Add mir-check-debug pass to check MIR-level debug info.
git bisect good 39584ae5b5cbc817d19499b003d4eaba259c31b5
# good: [71699a998d4f648396a1a12820c0f04cc61f8e19] [flang][openacc] Enforce restriction on routine directive and clauses
git bisect good 71699a998d4f648396a1a12820c0f04cc61f8e19
# good: [511cfe9441955f20a8b93573fb9b62433b053550] Revert "Ensure SplitEdge to return the new block between the two given blocks"
git bisect good 511cfe9441955f20a8b93573fb9b62433b053550
# good: [14da25b4b2eedf8a16aae34edfefd7bcaa5ceae5] [mlir][sparse] scalarize reductions in for-loops during sparse codegen
git bisect good 14da25b4b2eedf8a16aae34edfefd7bcaa5ceae5
# good: [385e9a2a047bc0bee13a21a9016763e694a686a3] [DAGCombiner] Improve shift by select of constant
git bisect good 385e9a2a047bc0bee13a21a9016763e694a686a3
# bad: [31c0b8700b4f531b2353fbb0e72d6934f65814f8] Fix clang-ppc64le-rhel buildbot build error
git bisect bad 31c0b8700b4f531b2353fbb0e72d6934f65814f8
# bad: [3733463dbb58a29892be3872bd32f93cb9af492c] [IR][PGO] Add hot func attribute and use hot/cold attribute in func section
git bisect bad 3733463dbb58a29892be3872bd32f93cb9af492c
# good: [ee2cb90e3bbe5cc6d027b1f821458eb267da516f] [RISCV] Define vsadd/vsaddu/vssub/vssubu intrinsics.
git bisect good ee2cb90e3bbe5cc6d027b1f821458eb267da516f
# first bad commit: [3733463dbb58a29892be3872bd32f93cb9af492c] [IR][PGO] Add hot func attribute and use hot/cold attribute in func section

I do not have time at the moment to report this upstream.

[nickdesaulniers]

pretty sure I added support for these sections in the generic vmlinux linker script...I wonder if ppc is not using it?

[nathanchance]

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 0318ba436f34..37a91352aca2 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -85,7 +85,7 @@ SECTIONS
                ALIGN_FUNCTION();
 #endif
                /* careful! __ftr_alt_* sections need to be close to .text */
-               *(.text.hot TEXT_MAIN .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text);
+               *(.text.hot TEXT_MAIN .text.fixup .text.unlikely .text.unlikely.* .fixup __ftr_alt_* .ref.text);
 #ifdef CONFIG_PPC64
                *(.tramp.ftrace.text);
 #endif

is the fix I have. I will send it on Monday.

[nickdesaulniers]

You'll want to do the same for .text.hot.* (LLVM's sources referenced .text.unknown, but I haven't seen an issue related to those...yet).

[nathanchance]

Patch submitted: https://lore.kernel.org/r/20210104204850.990966-1-natechancellor@gmail.com

[nathanchance]

Patch appears to be accepted: https://git.kernel.org/powerpc/c/3ce47d95b734

[nathanchance]

Merged into mainline: https://git.kernel.org/linus/3ce47d95b7346dcafd9bed3556a8d072cb2b8571