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[PATCH 03/19] arm64: ilp32: add documentation on the ILP32 ABI for ARM64
- From: Yury Norov <ynorov at caviumnetworks dot com>
- To: <arnd at arndb dot de>, <catalin dot marinas at arm dot com>, <linux-arm-kernel at lists dot infradead dot org>, <linux-kernel at vger dot kernel dot org>, <linux-doc at vger dot kernel dot org>, <linux-arch at vger dot kernel dot org>, <libc-alpha at sourceware dot org>
- Cc: <schwidefsky at de dot ibm dot com>, <heiko dot carstens at de dot ibm dot com>, <ynorov at caviumnetworks dot com>, <pinskia at gmail dot com>, <broonie at kernel dot org>, <joseph at codesourcery dot com>, <christoph dot muellner at theobroma-systems dot com>, <bamvor dot zhangjian at huawei dot com>, <szabolcs dot nagy at arm dot com>, <klimov dot linux at gmail dot com>, <Nathan_Lynch at mentor dot com>, <agraf at suse dot de>, <Prasun dot Kapoor at caviumnetworks dot com>, <kilobyte at angband dot pl>, <geert at linux-m68k dot org>, <philipp dot tomsich at theobroma-systems dot com>, <manuel dot montezelo at gmail dot com>, <linyongting at huawei dot com>, <maxim dot kuvyrkov at linaro dot org>, <davem at davemloft dot net>
- Date: Sat, 18 Jun 2016 02:54:12 +0300
- Subject: [PATCH 03/19] arm64: ilp32: add documentation on the ILP32 ABI for ARM64
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- References: <1466207668-10549-1-git-send-email-ynorov at caviumnetworks dot com>
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Based on Andrew Pinski's patch-series.
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
---
Documentation/arm64/ilp32.txt | 54 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)
create mode 100644 Documentation/arm64/ilp32.txt
diff --git a/Documentation/arm64/ilp32.txt b/Documentation/arm64/ilp32.txt
new file mode 100644
index 0000000..d5faa31
--- /dev/null
+++ b/Documentation/arm64/ilp32.txt
@@ -0,0 +1,54 @@
+ILP32 AARCH64 SYSCALL ABI
+=========================
+
+This document describes the ILP32 syscall ABI and where it differs
+from the generic compat linux syscall interface.
+
+AARCH64/ILP32 userspace can potentially access top halves of registers that
+are passed as syscall arguments, so such registers (w0-w7) are deloused.
+
+AARCH64/ILP32 provides next types turned to 64-bit (comparing to AARCH32):
+ino_t is u64 type.
+off_t is s64 type.
+blkcnt_t is s64 type.
+fsblkcnt_t is u64 type.
+fsfilcnt_t is u64 type.
+
+AARCH64/ILP32 ABI uses standard syscall table which can be found at
+include/uapi/asm-generic/unistd.h, with the exceptions listed below.
+
+Syscalls which pass 64bit values are handled by the code shared from
+AARCH32 and pass that value as a pair. Next syscalls are affected:
+fadvise64_64()
+fallocate()
+ftruncate64()
+pread64 ()
+pwrite64()
+readahead()
+sync_file_range()
+truncate64()
+sys_mmap()
+
+ptrace() syscall is handled by compat version.
+
+fcntl64() syscall is handled by non-compat handler as struct flock for ilp32
+is the same as for lp64
+
+shmat() syscall is handled by non-compat handler as aarch64/ilp32 has no
+limitation on 4-pages alignement for shared memory.
+
+Syscalls which take a pointer to stat, stat64, statfs, statfs64
+structures are now routed to native handlers directly, as aarch64/ilp32
+defines userspace ino_t, off_t, blkcnt_t, fsblkcnt_t, fsfilcnt_t types
+as 64-bit and it makes that structures have same layout as lp64.
+Next syscalls are affected:
+fstatat64()
+fstat64()
+statfs64()
+fstatfs64()
+
+struct rt_sigframe is redefined and contains struct compat_siginfo,
+as compat syscalls expects, and struct ilp32_sigframe, to handle
+AARCH64 register set and 32-bit userspace register representation.h
+
+elf_gregset_t is taken from lp64 to handle registers properly.
--
2.7.4