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Bug#935536: marked as done (Compiling Linux with "bdver2" gcc optimization option)

Your message dated Fri, 23 Apr 2021 13:31:09 +0200
with message-id <YIKv/XQ1B93QHnfr@eldamar.lan>
and subject line Re: Bug#935536: Fwd: Compiling Linux with "bdver2" gcc optimization option
has caused the Debian Bug report #935536,
regarding Compiling Linux with "bdver2" gcc optimization option
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
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immediately.)


-- 
935536: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=935536
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: linux-kbuild-4.19
Version: 4.19.37-5+deb10u2

In order to achieve Linux kernel optimized for my CPU AMD FX-8350
Bulldozer2 I changed the "Processor family" to
"Opteron/Athlon64/Hammer/K8" under "Processor type and features" menu of
the configuration program of the kernel (make menuconfig). Then I
changed line 121 of linux-source-4.19/arch/x86/Makefile
from:

cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)

to:

cflags-$(CONFIG_MK8) += $(call cc-option,-march=bdver2) \
<Tab>	<Tab>	$(call cc-option,-mtune=bdver2,$(call
cc-option,-mtune=generic))

compiling the kernel up to Debian 9.x Stretch all worked fine but with
Debian 10 Buster I get a lot of warning messages:

~/linux-source-4.19$ time make -s -j9 ; make -s -j9 modules
<snip>
mm/memory.o: warning: objtool: remap_pfn_range()+0xd5: unsupported
intra-function call
mm/memory.o: warning: objtool: If this is a retpoline, please patch it
in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.
mm/mlock.o: warning: objtool: __munlock_isolate_lru_page()+0xd6: stack
state mismatch: cfa1=7+64 cfa2=7+56
mm/mlock.o: warning: objtool: clear_page_mlock()+0x39: unsupported
instruction in callable function
mm/mlock.o: warning: objtool: mlock_vma_page()+0x8e: sibling call from
callable instruction with modified stack frame
mm/mlock.o: warning: objtool: munlock_vma_page()+0x163: return with
modified stack frame
kernel/bpf/stackmap.o: warning: objtool: bpf_get_stack()+0x68: return
with modified stack frame
kernel/bpf/sockmap.o: warning: objtool: bpf_exec_tx_verdict()+0x436:
stack state mismatch: cfa1=7+168 cfa2=7+160
kernel/power/qos.o: warning: objtool: pm_qos_remove_request()+0x6d:
return with modified stack frame
arch/x86/kernel/dumpstack.o: warning: objtool: __die()+0xc2: return with
modified stack frame
arch/x86/kernel/cpu/amd.o: warning: objtool: bsp_init_amd()+0xb1: can't
find jump dest instruction at .text+0x193
arch/x86/kvm/x86.o: warning: objtool: kvm_set_cr3()+0x18: can't find
jump dest instruction at .text+0x5cc0
arch/x86/kernel/ldt.o: warning: objtool: write_ldt()+0x110: can't find
jump dest instruction at .text+0x56a
mm/mmap.o: warning: objtool: init_user_reserve()+0x34: return with
modified stack frame
mm/mmap.o: warning: objtool: init_admin_reserve()+0x34: return with
modified stack frame
mm/mmap.o: warning: objtool: vm_brk_flags()+0x55: stack state mismatch:
cfa1=7+80 cfa2=7+72
mm/mmap.o: warning: objtool: do_mmap()+0x1bf: stack state mismatch:
cfa1=7+80 cfa2=7+72
mm/mprotect.o: warning: objtool: change_protection()+0x4f5: can't find
jump dest instruction at .text+0x5a3
mm/mremap.o: warning: objtool: move_page_tables()+0x60: stack state
mismatch: cfa1=7+144 cfa2=7+136
mm/mremap.o: warning: objtool: __se_sys_mremap()+0x12d: stack state
mismatch: cfa1=7+160 cfa2=7+152
arch/x86/kernel/sys_x86_64.o: warning: objtool: get_align_mask()+0x1d:
can't find jump dest instruction at .text+0x2f
mm/page_vma_mapped.o: warning: objtool: check_pte()+0x108: return with
modified stack frame
mm/page_vma_mapped.o: warning: objtool: page_vma_mapped_walk()+0x15e:
stack state mismatch: cfa1=7+56 cfa2=7+40
mm/pagewalk.o: warning: objtool: __walk_page_range()+0x1be: return with
modified stack frame
kernel/printk/printk.o: warning: objtool: devkmsg_write.cold.15()+0x30:
can't find jump dest instruction at .text.unlikely+0x2a1
arch/x86/kvm/emulate.o: warning: objtool: rsm_load_state_32()+0x2e2:
can't find jump dest instruction at .text+0xfa4
arch/x86/kvm/i8254.o: warning: objtool: pit_ioport_read()+0x141: can't
find jump dest instruction at .text+0x7cb
arch/x86/kvm/mmu.o: warning: objtool:
kvm_calc_tdp_mmu_root_page_role()+0xb: can't find jump dest instruction
at .text+0x3fd
arch/x86/kvm/lapic.o: warning: objtool: recalculate_apic_map()+0x2f6:
can't find jump dest instruction at .text+0x968
mm/rmap.o: warning: objtool: try_to_unmap_one()+0x4d1: can't find jump
dest instruction at .text+0x185b
arch/x86/kvm/ioapic.o: warning: objtool:
rtc_irq_eoi_tracking_reset()+0x45: return with modified stack frame
arch/x86/kvm/ioapic.o: warning: objtool: ioapic_mmio_write()+0x62: stack
state mismatch: cfa1=7+48 cfa2=7+40
arch/x86/kvm/ioapic.o: warning: objtool: ioapic_mmio_read()+0xe5: stack
state mismatch: cfa1=7+64 cfa2=7+56
arch/x86/kvm/ioapic.o: warning: objtool: kvm_get_ioapic()+0x72: return
with modified stack frame
arch/x86/kvm/ioapic.o: warning: objtool: kvm_set_ioapic()+0x105: return
with modified stack frame
arch/x86/kvm/irq_comm.o: warning: objtool: kvm_set_msi_irq()+0x60:
return with modified stack frame
kernel/rcu/sync.o: warning: objtool: rcu_sync_init()+0x52: return with
modified stack frame
mm/vmalloc.o: warning: objtool: vmalloc_to_page()+0x150: return with
modified stack frame
mm/vmalloc.o: warning: objtool: vunmap_page_range()+0x2fc: return with
modified stack frame
mm/vmalloc.o: warning: objtool: vm_unmap_ram()+0x11f: sibling call from
callable instruction with modified stack frame
mm/vmalloc.o: warning: objtool: vmap_page_range_noflush()+0x2ec: return
with modified stack frame
mm/vmalloc.o: warning: objtool: vread()+0x1cf: stack state mismatch:
cfa1=7+96 cfa2=7+88
mm/vmalloc.o: warning: objtool: vwrite()+0x176: stack state mismatch:
cfa1=7+96 cfa2=7+88
arch/x86/kvm/cpuid.o: warning: objtool: do_cpuid_ent()+0x6b4: can't find
jump dest instruction at .text+0xba6
arch/x86/kvm/pmu.o: warning: objtool: reprogram_fixed_counter()+0xbb:
can't find jump dest instruction at .text+0x37d
kernel/rcu/srcutree.o: warning: objtool: process_srcu()+0x50: stack
state mismatch: cfa1=7+128 cfa2=7+120
kernel/rcu/srcutree.o: warning: objtool: __call_srcu()+0xba: sibling
call from callable instruction with modified stack frame
arch/x86/kernel/alternative.o: warning: objtool:
apply_alternatives()+0x10f: stack state mismatch: cfa1=7+336 cfa2=7+328
arch/x86/kernel/alternative.o: warning: objtool: apply_paravirt()+0x118:
stack state mismatch: cfa1=7+296 cfa2=7+288
arch/x86/kvm/hyperv.o: warning: objtool:
kvm_hv_notify_acked_sint()+0x4a: can't find jump dest instruction at
.text+0x20c
mm/madvise.o: warning: objtool: swapin_walk_pmd_entry()+0x1ec: stack
state mismatch: cfa1=7+88 cfa2=7+80
mm/madvise.o: warning: objtool: madvise_free_pte_range()+0x39e: stack
state mismatch: cfa1=7+136 cfa2=7+128
arch/x86/kernel/tsc_msr.o: warning: objtool: cpu_khz_from_msr()+0x99:
can't find jump dest instruction at .text+0x36
kernel/rcu/tree.o: warning: objtool: rcu_exp_wait_wake()+0x224: return
with modified stack frame
kernel/rcu/tree.o: warning: objtool:
_synchronize_rcu_expedited.constprop.55()+0x1c7: stack state mismatch:
cfa1=7+192 cfa2=7+184
arch/x86/kernel/tsc.o: warning: objtool:
pit_hpet_ptimer_calibrate_cpu()+0x1c4: stack state mismatch: cfa1=7+112
cfa2=7+104
arch/x86/kernel/tsc.o: warning: objtool:
tsc_refine_calibration_work()+0xd8: stack state mismatch: cfa1=7+48
cfa2=7+40
</snip>

I guess that objtool has stopped recognize CPU instructions for
-march=bdver2 gcc optimization flag. The only workaround I know it is to
use -march=bdver1 instead this compiles without warnings.
Is there a way to get the kernel optimized for my CPU as it happened in
all the previous Debian versions?

Kind regards
-- 
Franco Martelli

--- End Message ---
--- Begin Message --- 
Hi,

On Mon, Oct 12, 2020 at 05:11:29PM +0200, Franco Martelli wrote:
> The Objtools maintainer told me to ignore the warnings unless live
> patching it's used. This probably it means "Won't Fix" status to this
> bug report, however if some kernel hacker will want to fix it I would be
> so glad to see those warnings go away.

I will close now this bug, given we can consider it wontfix and if
then upstream will (has already?) fixed the issue which will go later
on into Debian.

Trying to clean up the open list of bugs, this seems a candidate which
we can close.

Regards,
Salvatore

--- End Message ---
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