Messages in this thread Patch in this message | | | Date | Thu, 14 May 2015 14:23:21 -0700 | From | Laura Abbott <> | Subject | Re: [PATCH] ARM: module: Add ".ref.text" to arm unwind tables |
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On 05/13/2015 08:20 AM, Vignesh Radhakrishnan wrote: > Functions inside kernel modules that use __ref > will end up being placed in .ARM.exidx.ref.text > section by gcc. > > Currently we don't consider adding these functions > to arm unwind tables. > > Hence, if we turn slub debug on by default we end up > with the messages of this sort: > > unwind: Index not found bf0011e0 > > This is because slub debug saves stack trace of > allocation's and free's. Therefore, we end up seeing > a flood of these messages in dmesg since its not > able to locate these functions. > > Fix this by adding .ref.text section to arm unwind tables. >
With this patch, I go from
------------[ cut here ]------------ WARNING: CPU: 0 PID: 63 at drivers/misc/test.c:12 that_function+0x10/0x2c [test]() Modules linked in: test(P+) CPU: 0 PID: 63 Comm: insmod Tainted: P 4.1.0-rc2+ #28 Hardware name: ARM-Versatile PB [<c001a590>] (unwind_backtrace) from [<c0017b84>] (show_stack+0x10/0x14) [<c0017b84>] (show_stack) from [<c0022370>] (warn_slowpath_common+0x78/0xb0) [<c0022370>] (warn_slowpath_common) from [<c0022444>] (warn_slowpath_null+0x1c/0x24) [<c0022444>] (warn_slowpath_null) from [<bf000048>] (that_function+0x10/0x2c [test]) unwind: Index not found bf000048 ---[ end trace 3e24f8edd90f3b27 ]---
to
------------[ cut here ]------------ WARNING: CPU: 0 PID: 63 at drivers/misc/test.c:12 that_function+0x10/0x2c [test]() Modules linked in: test(P+) CPU: 0 PID: 63 Comm: insmod Tainted: P 4.1.0-rc2+ #30 Hardware name: ARM-Versatile PB [<c001a5d0>] (unwind_backtrace) from [<c0017b84>] (show_stack+0x10/0x14) [<c0017b84>] (show_stack) from [<c0022770>] (warn_slowpath_common+0x78/0xb0) [<c0022770>] (warn_slowpath_common) from [<c0022844>] (warn_slowpath_null+0x1c/0x24) [<c0022844>] (warn_slowpath_null) from [<bf000048>] (that_function+0x10/0x2c [test]) [<bf000048>] (that_function [test]) from [<bf002010>] (awesome_module+0x10/0x1c [test]) [<bf002010>] (awesome_module [test]) from [<c0009710>] (do_one_initcall+0x80/0x1dc) [<c0009710>] (do_one_initcall) from [<c02d14e0>] (do_init_module+0x58/0x1a8) [<c02d14e0>] (do_init_module) from [<c0063940>] (load_module+0x170c/0x1c38) [<c0063940>] (load_module) from [<c0063f38>] (SyS_init_module+0xcc/0x124) [<c0063f38>] (SyS_init_module) from [<c0014900>] (ret_fast_syscall+0x0/0x30) ---[ end trace 554c9ff461eb2505 ]---
Tested-by: Laura Abbott <labbott@redhat.com>
> Signed-off-by: Vignesh Radhakrishnan <vigneshr@codeaurora.org> > --- > arch/arm/include/asm/module.h | 1 + > arch/arm/kernel/module.c | 4 ++++ > 2 files changed, 5 insertions(+) > > diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h > index ed690c4..17640c9 100644 > --- a/arch/arm/include/asm/module.h > +++ b/arch/arm/include/asm/module.h > @@ -14,6 +14,7 @@ enum { > ARM_SEC_DEVEXIT, > ARM_SEC_HOT, > ARM_SEC_UNLIKELY, > + ARM_SEC_REF, > ARM_SEC_MAX, > }; > > diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c > index 2e11961..846b888 100644 > --- a/arch/arm/kernel/module.c > +++ b/arch/arm/kernel/module.c > @@ -308,6 +308,8 @@ int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs, > maps[ARM_SEC_UNLIKELY].unw_sec = s; > else if (strcmp(".ARM.exidx.text.hot", secname) == 0) > maps[ARM_SEC_HOT].unw_sec = s; > + else if (strcmp(".ARM.exidx.ref.text", secname) == 0) > + maps[ARM_SEC_REF].unw_sec = s; > else if (strcmp(".init.text", secname) == 0) > maps[ARM_SEC_INIT].txt_sec = s; > else if (strcmp(".text", secname) == 0) > @@ -318,6 +320,8 @@ int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs, > maps[ARM_SEC_UNLIKELY].txt_sec = s; > else if (strcmp(".text.hot", secname) == 0) > maps[ARM_SEC_HOT].txt_sec = s; > + else if (strcmp(".ref.text", secname) == 0) > + maps[ARM_SEC_REF].txt_sec = s; > } > > for (i = 0; i < ARM_SEC_MAX; i++) >
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