Messages in this thread | | | Date | Wed, 17 Feb 2016 18:11:37 -0500 (EST) | From | Nicolas Pitre <> | Subject | Re: [PATCH] ARM: move __kuser_cmpxchg{32,64} into .kprobes.text |
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On Wed, 17 Feb 2016, Arnd Bergmann wrote:
> When kprobes is used, most of the entry-armv.S file is put into the .kprobes.text > section rather than .text, but the kuser_cmpxchg64_fixup and kuser_cmpxchg32_fixup > code is not, which can lead to a link error when extremely large kernels get > built (typically for randconfig): > > arch/arm/kernel/built-in.o: In function `__dabt_usr': > :(.kprobes.text+0x47c): relocation truncated to fit: R_ARM_JUMP24 against `.text' > arch/arm/kernel/built-in.o: In function `__irq_usr': > :(.kprobes.text+0x4e4): relocation truncated to fit: R_ARM_JUMP24 against `.text' > arch/arm/kernel/built-in.o: In function `__fiq_usr': > :(.kprobes.text+0x740): relocation truncated to fit: R_ARM_JUMP24 against `.text' > > This moves the two remaining functions into the same section as the rest, > to avoid the link error. > > The current behavior has existed for many years and has not caused problems in > practice except for extreme randconfig builds, so the patch should not need to > get backported. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: b49c0f24cf67 ("[ARM] 4659/1: remove possibilities for spurious false negative with __kuser_cmpxchg") > Fixes: 785d3cd286f0 ("ARM kprobes: prevent some functions involved with kprobes from being probed")
Stylewise it might be worth having something like:
#ifdef CONFIG_KPROBES #define KPROBE_TEXT .section .kprobes.text,"ax",%progbits #else #define KPROBE_TEXT .text #endif
and then use that throughout. Then...
Acked-by: Nicolas Pitre <nico@linaro.org>
> --- > arch/arm/kernel/entry-armv.S | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S > index e2550500486d..030e43a0dce8 100644 > --- a/arch/arm/kernel/entry-armv.S > +++ b/arch/arm/kernel/entry-armv.S > @@ -895,7 +895,11 @@ __kuser_cmpxchg64: @ 0xffff0f60 > rsbs r0, r3, #0 @ set return val and C flag > ldmfd sp!, {r4, r5, r6, pc} > > +#ifdef CONFIG_KPROBES > + .section .kprobes.text,"ax",%progbits > +#else > .text > +#endif > kuser_cmpxchg64_fixup: > @ Called from kuser_cmpxchg_fixup. > @ r4 = address of interrupted insn (must be preserved). > @@ -953,7 +957,11 @@ __kuser_cmpxchg: @ 0xffff0fc0 > rsbs r0, r3, #0 @ set return val and C flag > usr_ret lr > > +#ifdef CONFIG_KPROBES > + .section .kprobes.text,"ax",%progbits > +#else > .text > +#endif > kuser_cmpxchg32_fixup: > @ Called from kuser_cmpxchg_check macro. > @ r4 = address of interrupted insn (must be preserved). > -- > 2.7.0 > >
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