linux/arch/arm/kernel
Ard Biesheuvel 31b96cae5c ARM: 8515/2: move .vectors and .stubs sections back into the kernel VMA
Commit b9b32bf70f ("ARM: use linker magic for vectors and vector stubs")
updated the linker script to emit the .vectors and .stubs sections into a
VMA range that is zero based and disjoint from the normal static kernel
region. The reason for that was that this way, the sections can be placed
exactly 4 KB apart, while the payload of the .vectors section is only 32
bytes.

Since the symbols that are part of the .stubs section are emitted into the
kallsyms table, they appear with zero based addresses as well, e.g.,

  00001004 t vector_rst
  00001020 t vector_irq
  000010a0 t vector_dabt
  00001120 t vector_pabt
  000011a0 t vector_und
  00001220 t vector_addrexcptn
  00001240 t vector_fiq
  00001240 T vector_fiq_offset

As this confuses perf when it accesses the kallsyms tables, commit
7122c3e915 ("scripts/link-vmlinux.sh: only filter kernel symbols for
arm") implemented a somewhat ugly special case for ARM, where the value
of CONFIG_PAGE_OFFSET is passed to scripts/kallsyms, and symbols whose
addresses are below it are filtered out. Note that this special case only
applies to CONFIG_XIP_KERNEL=n, not because the issue the patch addresses
exists only in that case, but because finding a limit below which to apply
the filtering is not entirely straightforward.

Since the .vectors and .stubs sections contain position independent code
that is never executed in place, we can emit it at its most likely runtime
VMA (for more recent CPUs), which is 0xffff0000 for the vector table and
0xffff1000 for the stubs. Not only does this fix the perf issue with
kallsyms, allowing us to drop the special case in scripts/kallsyms
entirely, it also gives debuggers a more realistic view of the address
space, and setting breakpoints or single stepping through code in the
vector table or the stubs is more likely to work as expected on CPUs that
use a high vector address. E.g.,

  00001240 A vector_fiq_offset
  ...
  c0c35000 T __init_begin
  c0c35000 T __vectors_start
  c0c35020 T __stubs_start
  c0c35020 T __vectors_end
  c0c352e0 T _sinittext
  c0c352e0 T __stubs_end
  ...
  ffff1004 t vector_rst
  ffff1020 t vector_irq
  ffff10a0 t vector_dabt
  ffff1120 t vector_pabt
  ffff11a0 t vector_und
  ffff1220 t vector_addrexcptn
  ffff1240 T vector_fiq

(Note that vector_fiq_offset is now an absolute symbol, which kallsyms
already ignores by default)

The LMA footprint is identical with or without this change, only the VMAs
are different:

  Before:
  Idx Name          Size      VMA       LMA       File off  Algn
   ...
   14 .notes        00000024  c0c34020  c0c34020  00a34020  2**2
                    CONTENTS, ALLOC, LOAD, READONLY, CODE
   15 .vectors      00000020  00000000  c0c35000  00a40000  2**1
                    CONTENTS, ALLOC, LOAD, READONLY, CODE
   16 .stubs        000002c0  00001000  c0c35020  00a41000  2**5
                    CONTENTS, ALLOC, LOAD, READONLY, CODE
   17 .init.text    0006b1b8  c0c352e0  c0c352e0  00a452e0  2**5
                    CONTENTS, ALLOC, LOAD, READONLY, CODE
   ...

  After:
  Idx Name          Size      VMA       LMA       File off  Algn
   ...
   14 .notes        00000024  c0c34020  c0c34020  00a34020  2**2
                    CONTENTS, ALLOC, LOAD, READONLY, CODE
   15 .vectors      00000020  ffff0000  c0c35000  00a40000  2**1
                    CONTENTS, ALLOC, LOAD, READONLY, CODE
   16 .stubs        000002c0  ffff1000  c0c35020  00a41000  2**5
                    CONTENTS, ALLOC, LOAD, READONLY, CODE
   17 .init.text    0006b1b8  c0c352e0  c0c352e0  00a452e0  2**5
                    CONTENTS, ALLOC, LOAD, READONLY, CODE
   ...

Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2016-02-11 15:33:39 +00:00
..
.gitignore
arch_timer.c arch_timer: Move to generic sched_clock framework 2013-10-09 16:54:10 -07:00
armksyms.c ARM: 8479/2: add implementation for arm-smccc 2016-01-04 16:24:34 +00:00
asm-offsets.c Merge branch 'exec_domain_rip_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2015-04-15 13:53:55 -07:00
atags_compat.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
atags_parse.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
atags_proc.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
atags.h ARM: 8495/1: ATAGS: move save_atags() to arch/arm/include/asm/setup.h 2016-01-04 11:26:00 +00:00
bios32.c ARM/PCI: Move align_resource function pointer to pci_host_bridge structure 2015-11-25 13:23:38 -06:00
calls.S ARM: wire up mlock2 syscall 2015-11-18 11:20:24 +00:00
cpuidle.c ARM: 8485/1: cpuidle: remove cpu parameter from the cpuidle_ops suspend hook 2015-12-22 12:09:43 +00:00
crash_dump.c ARM: 8012/1: kdump: Avoid overflow when converting pfn to physaddr 2014-04-07 12:10:00 +01:00
debug.S ARM: unify MMU/!MMU addruart calls 2015-05-20 23:09:51 +02:00
devtree.c ARM: make default platform work for NOMMU 2015-12-17 17:45:47 +01:00
dma-isa.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
dma.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
early_printk.c
efi.c ARM: wire up UEFI init and runtime support 2015-12-13 19:18:30 +01:00
elf.c
entry-armv.S ARM: 8515/2: move .vectors and .stubs sections back into the kernel VMA 2016-02-11 15:33:39 +00:00
entry-common.S Merge branch 'uaccess' into fixes 2015-09-11 19:18:28 +01:00
entry-ftrace.S ARM: replace BSYM() with badr assembly macro 2015-05-08 17:33:50 +01:00
entry-header.S ARM: entry: provide uaccess assembly macro hooks 2015-08-26 20:27:02 +01:00
entry-v7m.S ARM: 8450/1: v7-M: Use ret_to_user_from_irq in PendSV handler 2015-11-16 18:34:37 +00:00
fiq.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
fiqasm.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
ftrace.c ARM: kprobes: enable OPTPROBES for ARM 32 2015-01-13 16:10:17 +00:00
head-common.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
head-nommu.S ARM: 8383/1: nommu: avoid deprecated source register on mov 2015-06-12 21:18:48 +01:00
head.S Merge branch 'uaccess' into fixes 2015-09-11 19:18:28 +01:00
hibernate.c ARM: use virt_to_idmap() for soft_restart() 2016-02-08 15:48:32 +00:00
hw_breakpoint.c ARM: 8436/1: hw_breakpoint: remove unnecessary header 2015-10-03 16:36:44 +01:00
hyp-stub.S Here are the PPC and ARM changes for KVM, which I separated because 2014-08-07 11:35:30 -07:00
insn.c
io.c ARM: io.c: clean up EXPORT_SYMBOL()s 2014-11-21 15:25:02 +00:00
irq.c ARM: 8499/1: irq: l2c: do not print error in case of missing l2c from 2016-01-26 23:49:02 +00:00
isa.c arm: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:15 -07:00
iwmmxt.S ARM: 8221/1: PJ4: allow building in Thumb-2 mode 2014-12-03 16:08:00 +00:00
jump_label.c jump_label: Rename JUMP_LABEL_{EN,DIS}ABLE to JUMP_LABEL_{JMP,NOP} 2015-08-03 11:34:12 +02:00
kgdb.c ARM: 8428/1: kgdb: Fix registers on sleeping tasks 2015-10-03 16:36:45 +01:00
machine_kexec.c ARM: use virt_to_idmap() for soft_restart() 2016-02-08 15:48:32 +00:00
Makefile xen: features and fixes for 4.5-rc0 2016-01-12 13:05:36 -08:00
module-plts.c module: use a structure to encapsulate layout. 2015-12-04 22:46:25 +01:00
module.c ARM: 8220/1: allow modules outside of bl range 2015-05-08 10:42:34 +01:00
module.lds ARM: 8220/1: allow modules outside of bl range 2015-05-08 10:42:34 +01:00
opcodes.c
paravirt.c arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops 2015-12-21 14:40:54 +00:00
patch.c ARM: probes: move all probe code to dedicate directory 2015-01-09 09:36:50 +00:00
perf_callchain.c arm: perf: factor out callchain code 2014-10-30 12:16:58 +00:00
perf_event_v6.c arm: perf: factor arm_pmu core out to drivers 2015-07-31 15:01:14 +01:00
perf_event_v7.c ARM: perf: add format entry to describe event -> config mapping 2015-12-22 14:42:57 +00:00
perf_event_xscale.c arm: perf: factor arm_pmu core out to drivers 2015-07-31 15:01:14 +01:00
perf_regs.c perf: Move task_pt_regs sampling into arch code 2015-01-09 11:12:28 +01:00
pj4-cp0.c ARM: 8452/3: PJ4: make coprocessor access sequences buildable in Thumb2 mode 2016-01-04 11:12:10 +00:00
process.c ARM: report proper DACR value in oops dumps 2015-12-04 19:20:48 +00:00
psci_smp.c ARM: use const and __initconst for smp_operations 2015-12-01 22:17:45 +01:00
ptrace.c Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
reboot.c ARM: make virt_to_idmap() return unsigned long 2016-02-08 15:47:28 +00:00
reboot.h ARM: move reboot code to arch/arm/kernel/reboot.c 2015-04-02 09:50:45 +01:00
relocate_kernel.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
return_address.c ARM: 8328/1: remove empty preprocessor #else branch 2015-03-28 16:54:53 +00:00
setup.c Merge branch 'devel-stable' into for-linus 2016-01-12 13:41:03 +00:00
signal.c Merge branch 'fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2015-09-19 21:05:02 -07:00
sigreturn_codes.S ARM: 7895/1: signal: fix armv7-m build issue in sigreturn_codes.S 2013-11-30 22:21:00 +00:00
sleep.S ARM: fix new BSYM() usage introduced via for-arm-soc branch 2015-06-12 21:19:35 +01:00
smccc-call.S ARM: 8479/2: add implementation for arm-smccc 2016-01-04 16:24:34 +00:00
smp_scu.c ARM: 8122/1: smp_scu: enable SCU standby support 2014-08-02 08:51:53 +01:00
smp_tlb.c ARM: 8111/1: Enable erratum 798181 for Broadcom Brahma-B15 2014-07-24 14:40:26 +01:00
smp_twd.c ARM: clean up TWD after previous patch 2015-10-09 16:22:53 +01:00
smp.c ARM: 8488/1: Make IPI_CPU_BACKTRACE a "non-secure" SGI 2015-12-22 12:09:44 +00:00
stacktrace.c ARM: 8172/1: Use current_stack_pointer in save_stack_trace_tsk 2014-11-13 23:58:03 +00:00
suspend.c ARM: 8248/1: pm: remove outdated comment 2015-01-21 15:58:57 +00:00
swp_emulate.c ARM: 8475/1: SWP emulation: Restore original *data when failed 2015-12-15 11:51:42 +00:00
sys_arm.c
sys_oabi-compat.c [PATCH] arm: fix handling of F_OFD_... in oabi_fcntl64() 2015-12-29 13:04:21 -05:00
tcm.c ARM: 8388/1: tcm: Don't crash when TCM banks are protected by TrustZone 2015-06-06 10:37:28 +01:00
thumbee.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
time.c clocksource: cosmetic: Drop OF 'dependency' from symbols 2015-10-01 02:18:39 +02:00
topology.c ARM: 8497/1: initialize cpu_scale to its default 2016-01-26 23:49:02 +00:00
traps.c ARM: remove user cmpxchg syscall 2015-10-03 16:36:45 +01:00
unwind.c ARM: 8176/1: Use current_stack_pointer in unwind_backtrace 2014-11-13 23:58:09 +00:00
v7m.c ARM: 7828/1: ARMv7-M: implement restart routine common to all v7-M machines 2013-09-02 13:49:29 +01:00
vdso.c ARM: 8476/1: VDSO: use PTR_ERR_OR_ZERO for vma check 2015-12-17 10:29:01 +00:00
vmlinux-xip.lds.S ARM: 8515/2: move .vectors and .stubs sections back into the kernel VMA 2016-02-11 15:33:39 +00:00
vmlinux.lds.S ARM: 8515/2: move .vectors and .stubs sections back into the kernel VMA 2016-02-11 15:33:39 +00:00
xscale-cp0.c ARM: make xscale iwmmxt code multiplatform aware 2015-12-01 21:44:24 +01:00