[v6,01/19] arm64:ilp32: add documentation on the ILP32 ABI for ARM64

Commit Message

Yury Norov Nov. 17, 2015, 9:16 p.m. UTC

From: Philipp Tomsich <[e-mail]>

Based on Andrew Pinski's original patch-series and adapted with changes
to reduce the duplication of code-paths and resolve issue found during
LTP testing.

Reviewed-by: David Daney <[e-mail]>


Signed-off-by: Philipp Tomsich <[e-mail]>
Signed-off-by: Christoph Muellner <[e-mail]>
Signed-off-by: Yury Norov <[e-mail]>
Signed-off-by: Andrew Pinski <[e-mail]>
---
 Documentation/arm64/ilp32.txt | 47 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 Documentation/arm64/ilp32.txt

Comments

zhangjian Nov. 18, 2015, 8:09 a.m. UTC | #1

Hi, Yury

On 2015/11/18 5:16, Yury Norov wrote:
> From: Philipp Tomsich <[e-mail]>
> 
> Based on Andrew Pinski's original patch-series and adapted with changes
> to reduce the duplication of code-paths and resolve issue found during
> LTP testing.
> 
> Reviewed-by: David Daney <[e-mail]>
> 
> 
> Signed-off-by: Philipp Tomsich <[e-mail]>
> Signed-off-by: Christoph Muellner <[e-mail]>
> Signed-off-by: Yury Norov <[e-mail]>
> Signed-off-by: Andrew Pinski <[e-mail]>
> ---
>  Documentation/arm64/ilp32.txt | 47 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 47 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..93c09f2
> --- /dev/null
> +++ b/Documentation/arm64/ilp32.txt
> @@ -0,0 +1,47 @@
> +ILP32 AARCH64 SYSCALL ABI
> +=========================
> +Written by Andrew Pinski <[e-mail]>
> +Updated by Philipp Tomsich <[e-mail]>
> +Updated by Yury Norov <[e-mail]>
> +
> +
> +This document describes the ILP32 syscall ABI and where it differs
> +from the generic linux syscall interface.
> +
> +Some structures are changed to reduce the difference in the code path
> +for both ILP32 and LP64 ABIs for signal handling.
Given that user may upgrade from aarch32 to ILP32. How about add abi
comparison between aarch32 and aarch64 ilp32?

Regards

Bamvor

Patch

diff --git a/Documentation/arm64/ilp32.txt b/Documentation/arm64/ilp32.txt
new file mode 100644
index 0000000..93c09f2
--- /dev/null
+++ b/Documentation/arm64/ilp32.txt
@@ -0,0 +1,47 @@ 
+ILP32 AARCH64 SYSCALL ABI
+=========================
+Written by Andrew Pinski <[e-mail]>
+Updated by Philipp Tomsich <[e-mail]>
+Updated by Yury Norov <[e-mail]>
+
+
+This document describes the ILP32 syscall ABI and where it differs
+from the generic linux syscall interface.
+
+Some structures are changed to reduce the difference in the code path
+for both ILP32 and LP64 ABIs for signal handling.
+
+The following structures have been changed so the layout of the
+structures are the same between ILP32 and LP64 ABIs, including:
+ * sigval_t        contains pointers
+ * sigevent        Uses sigval_t which causes it to be the same.  Special
+                   handing is needed for reading; in the mq_notify syscall
+ * sigaction       Conversion is handled in the userland (glibc), as the
+		    userland data structures are defined in glibc anyway.
+
+A number of structures differ between ILP32 and LP64, including:
+ * timespec        uses time_t and suseconds_t
+ * timeval         uses time_t and suseconds_t
+ * stat            uses timespec/time_t
+ * semid64_ds      uses time_t.
+ * msqid64_ds      uses time_t.
+ * shmid64_ds      uses time_t.
+ * rt_sigframe     uses siginfo and ucontext.
+ * siginfo_t       uses clock_t and sigval_t
+ * ucontext        uses stack_t and sigset_t
+ * fd_set          This is done to avoid endian issues between ILP32 and
+		   LP64. Syscalls consuming fd_set use timespec.
+ * struct msgbuf   The specification of 'struct msgbuf' defines the 'mtype'
+                   field as a 'long' (i.e. 32bit for ILP32, but 64bit for
+		   LP64).  Functions that operate on 'struct msgbuf' need
+		   to be passed through the compat-syscalls to resolve
+		   this.
+ * stack_t         contains pointers (handled in the compatibility layer)
+
+Also the syscalls which normally would pass 64bit values as two arguments;
+now pass the 64bit value as one argument.  Also they have been renamed
+(removing the 64 from the name) to avoid confusion.
+
+The list of LP64 syscalls reused by ILP32 clients, and syscalls having
+ILP32-specific handlers is in arch/arm64/kernel/sys_ilp32.c
+