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Josh Stone 315eb8a2a1 x86: Fix compilation bug in kprobes' twobyte_is_boostable 
When compiling an i386_defconfig kernel with gcc-4.6.1-9.fc15.i686, I
noticed a warning about the asm operand for test_bit in kprobes'
can_boost.  I discovered that this caused only the first long of
twobyte_is_boostable[] to be output.

Jakub filed and fixed gcc PR50571 to correct the warning and this output
issue.  But to solve it for less current gcc, we can make kprobes'
twobyte_is_boostable[] non-const, and it won't be optimized out.

Before:

    CC      arch/x86/kernel/kprobes.o
  In file included from include/linux/bitops.h:22:0,
                   from include/linux/kernel.h:17,
                   from [...]/arch/x86/include/asm/percpu.h:44,
                   from [...]/arch/x86/include/asm/current.h:5,
                   from [...]/arch/x86/include/asm/processor.h:15,
                   from [...]/arch/x86/include/asm/atomic.h:6,
                   from include/linux/atomic.h:4,
                   from include/linux/mutex.h:18,
                   from include/linux/notifier.h:13,
                   from include/linux/kprobes.h:34,
                   from arch/x86/kernel/kprobes.c:43:
  [...]/arch/x86/include/asm/bitops.h: In function ‘can_boost.part.1’:
  [...]/arch/x86/include/asm/bitops.h:319:2: warning: use of memory input
        without lvalue in asm operand 1 is deprecated [enabled by default]

  $ objdump -rd arch/x86/kernel/kprobes.o | grep -A1 -w bt
       551:	0f a3 05 00 00 00 00 	bt     %eax,0x0
                          554: R_386_32	.rodata.cst4

  $ objdump -s -j .rodata.cst4 -j .data arch/x86/kernel/kprobes.o

  arch/x86/kernel/kprobes.o:     file format elf32-i386

  Contents of section .data:
   0000 48000000 00000000 00000000 00000000  H...............
  Contents of section .rodata.cst4:
   0000 4c030000                             L...

Only a single long of twobyte_is_boostable[] is in the object file.

After, without the const on twobyte_is_boostable:

  $ objdump -rd arch/x86/kernel/kprobes.o | grep -A1 -w bt
       551:	0f a3 05 20 00 00 00 	bt     %eax,0x20
                          554: R_386_32	.data

  $ objdump -s -j .rodata.cst4 -j .data arch/x86/kernel/kprobes.o

  arch/x86/kernel/kprobes.o:     file format elf32-i386

  Contents of section .data:
   0000 48000000 00000000 00000000 00000000  H...............
   0010 00000000 00000000 00000000 00000000  ................
   0020 4c030000 0f000200 ffff0000 ffcff0c0  L...............
   0030 0000ffff 3bbbfff8 03ff2ebb 26bb2e77  ....;.......&..w

Now all 32 bytes are output into .data instead.

Signed-off-by: Josh Stone <jistone@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-25 09:00:14 +02:00
..
acpi x86 idle: move mwait_idle_with_hints() to where it is used 2011-08-03 19:06:36 -04:00
apic x86, UV: Remove UV delay in starting slave cpus 2011-08-05 23:48:34 +02:00
cpu x86, perf: Check that current->mm is alive before getting user callchain 2011-08-31 15:56:31 +02:00
.gitignore
alternative.c x86-64: Move vread_tsc and vread_hpet into the vDSO 2011-07-14 17:57:05 -07:00
amd_gart_64.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
amd_nb.c x86, amd-nb: Rename CPU PCI id define for F4 2011-03-31 08:51:38 +02:00
apb_timer.c Merge branch 'timers-clocksource-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-23 10:34:47 -07:00
aperture_64.c x86, gart: Don't enforce GART aperture lower-bound by alignment 2011-04-18 10:31:38 -07:00
apm_32.c i8253: Cleanup outb/inb magic 2011-07-01 10:37:15 +02:00
asm-offsets.c x86, asm: Cleanup unnecssary macros in asm-offsets.c 2011-02-25 16:37:32 -08:00
asm-offsets_32.c lguest: use a special 1:1 linear pagetable mode until first switch. 2011-07-22 14:39:48 +09:30
asm-offsets_64.c x86: Partly unify asm-offsets_{32,64}.c 2011-02-10 13:31:37 +01:00
audit_64.c
bootflag.c
check.c x86: Don't check for BIOS corruption in first 64K when there's no need to 2011-03-09 16:36:41 +01:00
cpuid.c BKL: remove extraneous #include <smp_lock.h> 2010-11-17 08:59:32 -08:00
crash.c
crash_dump_32.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
crash_dump_64.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
devicetree.c Merge branch 'of-pci' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2011-07-22 14:54:02 -07:00
doublefault_32.c
dumpstack.c Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2011-05-19 18:24:11 -07:00
dumpstack_32.c x86, dumpstack: Correct stack dump info when frame pointer is available 2011-03-18 10:51:42 +01:00
dumpstack_64.c x86: Don't use frame pointer to save old stack on irq entry 2011-07-02 18:06:36 +02:00
e820.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
early-quirks.c x86, quirk: Fix SB600 revision check 2011-03-16 14:03:32 +01:00
early_printk.c x86, earlyprintk: Move mrst early console to platform/ and fix a typo 2010-12-06 20:52:04 +01:00
entry_32.S x86-32: Fix boot with CONFIG_X86_INVD_BUG 2011-08-25 13:27:14 -07:00
entry_64.S Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-tip 2011-08-12 20:46:24 -07:00
ftrace.c x86/ftrace: Fix compiler warning in ftrace.c 2011-05-25 19:56:26 -04:00
head.c
head32.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-05-19 18:08:06 -07:00
head64.c x86: Cleanup highmap after brk is concluded 2011-03-19 11:58:19 -07:00
head_32.S Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 20:01:36 -07:00
head_64.S x86, trampoline: Common infrastructure for low memory trampolines 2011-02-17 21:02:43 -08:00
hpet.c Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-22 17:05:15 -07:00
hw_breakpoint.c x86: Use this_cpu_ops to optimize code 2010-12-30 12:20:28 +01:00
i386_ksyms_32.c
i387.c treewide: fix potentially dangerous trailing ';' in #defined values/expressions 2011-07-21 14:10:00 +02:00
i8237.c x86: Use syscore_ops instead of sysdev classes and sysdevs 2011-03-23 22:15:54 +01:00
i8253.c x86: Use common i8253 clockevent 2011-07-01 10:37:14 +02:00
i8259.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
init_task.c
io_delay.c
ioport.c x86: Use bitmap library functions 2011-02-17 14:59:22 +01:00
irq.c x86: Don't unmask disabled irqs when migrating them 2011-05-19 14:51:08 +02:00
irq_32.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
irq_64.c
irq_work.c irq_work: Add generic hardirq context callbacks 2010-10-18 19:58:50 +02:00
irqinit.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
jump_label.c x86, cpu: Clean up and unify the NOP selection infrastructure 2011-04-18 16:40:21 -07:00
kdebugfs.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
kgdb.c perf: Add context field to perf_event 2011-07-01 11:06:38 +02:00
kprobes.c x86: Fix compilation bug in kprobes' twobyte_is_boostable 2011-10-25 09:00:14 +02:00
kvm.c KVM guest: KVM Steal time registration 2011-07-24 11:49:36 +03:00
kvmclock.c KVM guest: KVM Steal time registration 2011-07-24 11:49:36 +03:00
ldt.c
machine_kexec_32.c
machine_kexec_64.c x86, cleanups: Use clear_page/copy_page rather than memset/memcpy 2010-09-22 15:36:49 -07:00
Makefile Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-tip 2011-08-12 20:46:24 -07:00
mca_32.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
microcode_amd.c x86, microcode, AMD: Fix section header size check 2011-06-16 17:23:54 +02:00
microcode_core.c x86, microcode: Unregister syscore_ops after microcode unloaded 2011-03-29 11:12:04 +02:00
microcode_intel.c x86/microcode: Fix double vfree() and remove redundant pointer checks before vfree() 2010-12-27 14:33:30 +01:00
mmconf-fam10h_64.c x86-64: Fix and clean up AMD Fam10 MMCONF enabling 2010-11-18 13:41:35 +01:00
module.c modules: make arch's use default loader hooks 2011-07-24 22:06:04 +09:30
mpparse.c x86, ioapic: Consolidate mp_ioapics[] into 'struct ioapic' 2011-05-20 13:40:59 +02:00
msr.c BKL: remove extraneous #include <smp_lock.h> 2010-11-17 08:59:32 -08:00
paravirt-spinlocks.c
paravirt.c Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-tip 2011-08-12 20:46:24 -07:00
paravirt_patch_32.c
paravirt_patch_64.c
pci-calgary_64.c treewide: Convert uses of struct resource to resource_size(ptr) 2011-06-10 14:55:36 +02:00
pci-dma.c x86/PCI: Remove dma32_reserve_bootmem 2011-05-10 15:43:32 -07:00
pci-iommu_table.c arch/x86/kernel/pci-iommu_table.c: Convert sprintf_symbol to %pS 2011-05-10 10:21:35 +02:00
pci-nommu.c
pci-swiotlb.c
pcspeaker.c
probe_roms.c treewide: Convert uses of struct resource to resource_size(ptr) 2011-06-10 14:55:36 +02:00
process.c x86 idle: move mwait_idle_with_hints() to where it is used 2011-08-03 19:06:36 -04:00
process_32.c cpuidle: stop depending on pm_idle 2011-08-03 19:06:37 -04:00
process_64.c cpuidle: stop depending on pm_idle 2011-08-03 19:06:37 -04:00
ptrace.c perf: Add context field to perf_event 2011-07-01 11:06:38 +02:00
pvclock.c x86/pvclock: Zero last_value on resume 2010-11-28 09:33:20 +01:00
quirks.c x86, quirks: Use pci_dev->revision 2011-07-21 10:26:00 +02:00
reboot.c x86: Make Dell Latitude E6420 use reboot=pci 2011-07-21 11:47:17 -07:00
reboot_32.S x86, reboot: Fix relocations in reboot_32.S 2011-05-02 14:44:46 -07:00
reboot_fixups_32.c x86: Ce4100: Add reboot_fixup() for CE4100 2010-11-12 00:45:41 +01:00
relocate_kernel_32.S kexec, x86: Fix incorrect jump back address if not preserving context 2011-07-21 11:19:28 +02:00
relocate_kernel_64.S kexec, x86: Fix incorrect jump back address if not preserving context 2011-07-21 11:19:28 +02:00
resource.c x86: avoid high BIOS area when allocating address space 2010-12-17 10:01:30 -08:00
rtc.c x86/rtc: Don't recursively acquire rtc_lock 2011-09-21 16:16:09 +02:00
setup.c Merge branch 'linus' into x86/urgent 2011-05-26 13:51:35 +02:00
setup_percpu.c x86: Unify CPU -> NUMA node mapping between 32 and 64bit 2011-01-28 14:54:09 +01:00
signal.c x86: Kill handle_signal()->set_fs() 2011-07-14 21:46:20 -07:00
smp.c sched: Provide scheduler_ipi() callback in response to smp_send_reschedule() 2011-04-14 08:52:32 +02:00
smpboot.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-22 17:02:38 -07:00
stacktrace.c x86: Swap save_stack_trace_regs parameters 2011-06-14 22:48:51 -04:00
step.c x86-64: Add user_64bit_mode paravirt op 2011-08-04 16:13:49 -07:00
sys_i386_32.c
sys_x86_64.c
syscall_64.c
syscall_table_32.S All Arch: remove linkage for sys_nfsservctl system call 2011-08-26 15:09:58 -07:00
tboot.c net: remove mm.h inclusion from netdevice.h 2011-06-21 19:17:20 -07:00
tce_64.c
test_nx.c x86: Eliminate various 'set but not used' warnings 2011-05-21 19:10:33 +02:00
test_rodata.c
time.c i8253: Create linux/i8253.h and use it in all 8253 related files 2011-06-09 15:01:37 +02:00
tls.c
tls.h
topology.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
trampoline.c x86, trampoline: Common infrastructure for low memory trampolines 2011-02-17 21:02:43 -08:00
trampoline_32.S x86, trampoline: Common infrastructure for low memory trampolines 2011-02-17 21:02:43 -08:00
trampoline_64.S x86-64, trampoline: Remove unused variable 2011-02-18 15:50:36 -08:00
traps.c Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-tip 2011-08-12 20:46:24 -07:00
tsc.c Merge branches 'x86-detect-hyper-for-linus', 'x86-fpu-for-linus', 'x86-kexec-for-linus', 'x86-platform-for-linus', 'x86-quirks-for-linus', 'x86-tsc-for-linus' and 'x86-smpboot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-23 10:38:21 -07:00
tsc_sync.c
verify_cpu.S x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
vm86_32.c thp: split_huge_page_mm/vma 2011-01-13 17:32:41 -08:00
vmlinux.lds.S x86-64: Rework vsyscall emulation and add vsyscall= parameter 2011-08-10 19:26:46 -05:00
vsmp_64.c
vsyscall_64.c x86: Default to vsyscall=native for now 2011-10-11 08:23:34 +02:00
vsyscall_emu_64.S x86-64: Rework vsyscall emulation and add vsyscall= parameter 2011-08-10 19:26:46 -05:00
vsyscall_trace.h x86-64: Add vsyscall:emulate_vsyscall trace event 2011-08-04 16:13:53 -07:00
x86_init.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-05-19 18:08:06 -07:00
x8664_ksyms_64.c x86-64, mem: Convert memmove() to assembly file and fix return value bug 2011-01-25 16:58:39 -08:00
xsave.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00