From: Nathan_Lynch@mentor•com (Nathan Lynch)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v7 7/9] ARM: add vdso user-space code
Date: Tue, 1 Jul 2014 08:28:30 -0500 [thread overview]
Message-ID: <53B2B77E.7040904@mentor.com> (raw)
In-Reply-To: <53B1D6B8.7080806@amacapital.net>
On 06/30/2014 04:29 PM, Andy Lutomirski wrote:
> On 06/22/2014 08:11 PM, Nathan Lynch wrote:
>> +
>> +# Build rules
>> +targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.so.raw vdso.lds
>> +obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
>> +
>> +ccflags-y := -shared -fPIC -fno-common -fno-builtin -fno-stack-protector
>> +ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 \
>> + $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
>
> Does this need -DDISABLE_BRANCH_PROFILING?
Yes, thanks.
>> diff --git a/arch/arm/kernel/vdso/checkundef.sh b/arch/arm/kernel/vdso/checkundef.sh
>> new file mode 100755
>> index 000000000000..185c30da202b
>> --- /dev/null
>> +++ b/arch/arm/kernel/vdso/checkundef.sh
>> @@ -0,0 +1,9 @@
>> +#!/bin/sh
>> +nm="$1"
>> +file="$2"
>> +"$nm" -u "$file" | ( ret=0; while read discard symbol
>> +do
>> + echo "$file: undefined symbol $symbol"
>> + ret=1
>> +done ; exit $ret )
>> +exit $?
>
> This is just as buggy as the x86 version. make;make malfunctions.
>
> Can you rely on a new enough toolchain to use -Wl,--no-undefined?
Looks like relying on --no-undefined should be okay.
>> diff --git a/arch/arm/kernel/vdso/datapage.S b/arch/arm/kernel/vdso/datapage.S
>> new file mode 100644
>> index 000000000000..fbf36d75da06
>> --- /dev/null
>> +++ b/arch/arm/kernel/vdso/datapage.S
>> @@ -0,0 +1,15 @@
>> +#include <linux/linkage.h>
>> +#include <asm/asm-offsets.h>
>> +
>> + .align 2
>> +.L_vdso_data_ptr:
>> + .long _start - . - VDSO_DATA_SIZE
>> +
>> +ENTRY(__get_datapage)
>> + .cfi_startproc
>> + adr r0, .L_vdso_data_ptr
>> + ldr r1, [r0]
>> + add r0, r0, r1
>> + bx lr
>> + .cfi_endproc
>> +ENDPROC(__get_datapage)
>
> Can you translate this into English for the non-ARM-speakers here?
It's a PC-relative load of the data page. If someone knows how to make
this happen in the C portion of the vdso, it would might get us a little
speedup.
>> +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
>> +#define HOST_ORDER ELFDATA2LSB
>> +#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
>> +#define HOST_ORDER ELFDATA2MSB
>> +#endif
>> +
>> +static const char *outfile;
>> +
>> +static void cleanup(void)
>> +{
>> + if (error_message_count > 0 && outfile != NULL)
>> + unlink(outfile);
>> +}
>> +
>> +static Elf32_Word read_elf_word(Elf32_Word word, bool swap)
>> +{
>> + return swap ? bswap_32(word) : word;
>> +}
>> +
>> +static Elf32_Half read_elf_half(Elf32_Half half, bool swap)
>> +{
>> + return swap ? bswap_16(half) : half;
>> +}
>> +
>> +static void write_elf_word(Elf32_Word val, Elf32_Word *dst, bool swap)
>> +{
>> + *dst = swap ? bswap_32(val) : val;
>> +}
>
> The macros in arch/x86/vdso/vdso2c.c are IMO much nicer.
Respectfully, I think I'd disagree, but more importantly, vdso2c.c seems
to assume a little-endian target.
next prev parent reply other threads:[~2014-07-01 13:28 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-23 3:11 [PATCH v7 0/9] ARM: VDSO Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 1/9] clocksource: arm_arch_timer: change clocksource name if CP15 unavailable Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 2/9] clocksource: arm_arch_timer: enable counter access for 32-bit ARM Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 3/9] ARM: arch_timer: remove unused functions Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 4/9] arm64: " Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 5/9] ARM: place sigpage at a random offset above stack Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 6/9] ARM: miscellaneous vdso infrastructure, preparation Nathan Lynch
2014-06-30 10:11 ` Arnd Bergmann
2014-06-30 12:27 ` Nathan Lynch
2014-06-30 13:06 ` Arnd Bergmann
2014-06-23 3:11 ` [PATCH v7 7/9] ARM: add vdso user-space code Nathan Lynch
2014-06-28 9:53 ` Russell King - ARM Linux
2014-06-28 10:03 ` Russell King - ARM Linux
2014-06-30 15:56 ` Andy Lutomirski
2014-06-28 15:19 ` Nathan Lynch
2014-06-28 15:26 ` Russell King - ARM Linux
2014-06-28 16:13 ` Nathan Lynch
2014-06-28 18:12 ` Russell King - ARM Linux
2014-06-28 19:45 ` Nathan Lynch
2014-06-28 20:11 ` Russell King - ARM Linux
2014-06-28 21:35 ` Nathan Lynch
2014-06-29 8:34 ` Russell King - ARM Linux
2014-06-29 15:48 ` Nathan Lynch
2014-06-29 16:07 ` Russell King - ARM Linux
2014-06-29 23:04 ` Nathan Lynch
2014-06-30 21:33 ` Andy Lutomirski
2014-06-30 15:59 ` Andy Lutomirski
2014-06-30 16:50 ` Nathan Lynch
2014-06-30 21:29 ` Andy Lutomirski
2014-07-01 9:00 ` Will Deacon
2014-07-01 13:34 ` Nathan Lynch
2014-07-01 14:11 ` Andy Lutomirski
2014-07-01 13:28 ` Nathan Lynch [this message]
2014-07-01 14:56 ` Andy Lutomirski
2014-06-23 3:11 ` [PATCH v7 8/9] ARM: vdso initialization, mapping, and synchronization Nathan Lynch
2014-06-30 21:37 ` Andy Lutomirski
2014-07-01 9:03 ` Will Deacon
2014-07-01 14:11 ` Nathan Lynch
2014-07-01 14:15 ` Will Deacon
2014-07-01 14:17 ` Andy Lutomirski
2014-07-01 17:27 ` Christopher Covington
2014-07-02 14:40 ` Will Deacon
2014-07-02 15:54 ` Andy Lutomirski
2014-07-02 16:18 ` Nathan Lynch
2014-07-02 16:27 ` Will Deacon
2014-07-02 16:47 ` Andy Lutomirski
2014-07-02 17:24 ` Will Deacon
2014-07-02 18:34 ` Andy Lutomirski
2014-07-02 18:54 ` Will Deacon
2014-07-22 0:14 ` Andy Lutomirski
2014-07-22 8:13 ` Will Deacon
2014-07-01 14:01 ` Nathan Lynch
2014-07-01 14:09 ` Andy Lutomirski
2014-07-01 14:14 ` Russell King - ARM Linux
2014-06-23 3:11 ` [PATCH v7 9/9] ARM: add CONFIG_VDSO Kconfig and Makefile bits Nathan Lynch
2014-06-27 8:51 ` [PATCH v7 0/9] ARM: VDSO Jan Glauber
2014-06-27 8:57 ` Russell King - ARM Linux
2014-06-27 9:41 ` Ard Biesheuvel
2014-06-27 9:46 ` Russell King - ARM Linux
2014-06-27 17:01 ` Nathan Lynch
2014-06-28 9:42 ` Russell King - ARM Linux
2014-06-28 9:55 ` Russell King - ARM Linux
2014-06-28 14:49 ` Russell King - ARM Linux
2014-06-30 7:27 ` Arnd Bergmann
2014-06-30 7:43 ` Arnd Bergmann
2014-06-30 18:27 ` Nathan Lynch
2014-06-27 16:00 ` Nathan Lynch
2014-06-30 16:03 ` Andy Lutomirski
2014-06-30 8:12 ` Ard Biesheuvel
2014-07-01 16:34 ` Nathan Lynch
2014-07-01 20:08 ` Ard Biesheuvel
2014-07-01 22:44 ` Russell King - ARM Linux
2014-06-30 14:40 ` Will Deacon
2014-06-30 15:42 ` Nathan Lynch
2014-06-30 21:56 ` Andy Lutomirski
2014-07-01 9:04 ` Will Deacon
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