[PATCH] syscall(3): add more arches and improve error documentation

[PATCH] syscall(3): add more arches and improve error documentation

[Mike Frysinger]

Move the error register documentation into the main table rather than
listing them in sentences after the fact.

Add sparc error return details.

Add details for alpha/arc/m68k/microblaze/nios2/powerpc/superh/tile/xtensa.

Signed-off-by: Mike Frysinger <vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
---
 man2/syscall.2 | 77 ++++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 53 insertions(+), 24 deletions(-)

diff --git a/man2/syscall.2 b/man2/syscall.2
index ee87416..d35f1ef 100644
--- a/man2/syscall.2
+++ b/man2/syscall.2
@@ -150,47 +150,67 @@ The first table lists the instruction used to transition to kernel mode,
 so you might have to refer to
 .BR vdso (7)),
 the register used to indicate the system call number,
-and the register used to return the system call result.
+the register used to return the system call result,
+and the register used to signal an error.
 .if t \{\
 .ft CW
 \}
 .TS
-l l1 l l1 l.
-arch/ABI	instruction	syscall #	retval	Notes
+l	l	l	l	l	l.
+arch/ABI	instruction	syscall #	retval	error	Notes
 _
-arm/OABI	swi NR	-	a1	NR is syscall #
-arm/EABI	swi 0x0	r7	r0
-arm64	svc #0	x8	x0
-blackfin	excpt 0x0	P0	R0
-i386	int $0x80	eax	eax
-ia64	break 0x100000	r15	r8	See below
-mips	syscall	v0	v0	See below
-parisc	ble 0x100(%sr2, %r0)	r20	r28
-s390	svc 0	r1	r2	See below
-s390x	svc 0	r1	r2	See below
-sparc/32	t 0x10	g1	o0
-sparc/64	t 0x6d	g1	o0
-x86_64	syscall	rax	rax	See below
-x32	syscall	rax	rax	See below
+alpha	callsys	v0	a0	a3	See below *
+arc	trap0	r8	r0	-
+arm/OABI	swi NR	-	a1	-	NR is syscall #
+arm/EABI	swi 0x0	r7	r0	-
+arm64	svc #0	x8	x0	-
+blackfin	excpt 0x0	P0	R0	-
+i386	int $0x80	eax	eax	-
+ia64	break 0x100000	r15	r8	r10	See below *
+m68k	trap #0	d0	d0	-
+microblaze	brki r14,8	r12	r3	-
+mips	syscall	v0	v0	a3	See below *
+nios2	trap	r2	r2	r7
+parisc	ble 0x100(%sr2, %r0)	r20	r28	-
+powerpc	sc	r0	r3	r0	See below *
+s390	svc 0	r1	r2	-	See below **
+s390x	svc 0	r1	r2	-	See below **
+superh	trap #0x17	r3	r0	-	See below ****
+sparc/32	t 0x10	g1	o0	psr/csr	See below *
+sparc/64	t 0x6d	g1	o0	psr/csr	See below *
+tile	swint1	R10	R00	R01	See below *
+x86_64	syscall	rax	rax	-	See below ***
+x32	syscall	rax	rax	-	See below ***
+xtensa	syscall	a2	a2	-
 .TE
 .PP
+*
+On a few architectures,
+a register is used as a boolean (0 == no error while -1 == error) to signal the
+system call failed.
+The actual error value is still contained in the return register.
+On sparc, the carry bit (csr) in the processor status register (psr) is used
+instead of a full register.
+
+**
 For s390 and s390x, NR (the system call number)
 may be passed directly with "svc NR" if it is less than 256.
 
+***
 The x32 ABI uses the same instruction as the x86_64 ABI and is used on
 the same processors.
 To differentiate between them, the bit mask
 .I __X32_SYSCALL_BIT
 is bitwise-ORed into the system call number for system calls
 under the x32 ABI.
+Both syscall tables are available though, so setting the bit is not a hard
+requirement.
 
-On a few architectures,
-a register is used to indicate simple boolean failure of the system call:
-ia64 uses
-.I r10
-for this purpose,
-and mips uses
-.IR a3 .
+****
+On SuperH, the trap number controls the maximum number of args passed.
+A trap #0x10 can be used with only 0 arg syscalls,
+a trap #0x11 can be used with 0 or 1 arg syscalls,
+and so on up to 0x17 for 7 arg syscalls.
 .if t \{\
 .in
 .ft P
@@ -204,21 +224,30 @@ The second table shows the registers used to pass the system call arguments.
 l	l2	l2	l2	l2	l2	l2	l2	l.
 arch/ABI	arg1	arg2	arg3	arg4	arg5	arg6	arg7	Notes
 _
+alpha	a0	a1	a2	a3	a4	a5	-
+arc	r0	r1	r2	r3	r4	r5	-
 arm/OABI	a1	a2	a3	a4	v1	v2	v3
 arm/EABI	r0	r1	r2	r3	r4	r5	r6
 arm64	x0	x1	x2	x3	x4	x5	-
 blackfin	R0	R1	R2	R3	R4	R5	-
 i386	ebx	ecx	edx	esi	edi	ebp	-
 ia64	out0	out1	out2	out3	out4	out5	-
+m68k	d1	d2	d3	d4	d5	a0	-
+microblaze	r5	r6	r7	r8	r9	r10	-
 mips/o32	a0	a1	a2	a3	-	-	-	See below
 mips/n32,64	a0	a1	a2	a3	a4	a5	-
+nios2	r4	r5	r6	r7	r8	r9	-
 parisc	r26	r25	r24	r23	r22	r21	-
+powerpc	r3	r4	r5	r6	r7	r8	r9
 s390	r2	r3	r4	r5	r6	r7	-
 s390x	r2	r3	r4	r5	r6	r7	-
+superh	r4	r5	r6	r7	r0	r1	r2
 sparc/32	o0	o1	o2	o3	o4	o5	-
 sparc/64	o0	o1	o2	o3	o4	o5	-
+tile	R00	R01	R02	R03	R04	R05	-
 x86_64	rdi	rsi	rdx	r10	r8	r9	-
 x32	rdi	rsi	rdx	r10	r8	r9	-
+xtensa	a6	a3	a4	a5	a8	a9	-
 .TE
 .PP
 The mips/o32 system call convention passes
-- 
2.6.2

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Re: [PATCH] syscall(3): add more arches and improve error documentation

[Michael Kerrisk (man-pages)]

On 12/30/2015 03:00 AM, Mike Frysinger wrote:
> Move the error register documentation into the main table rather than
> listing them in sentences after the fact.
> 
> Add sparc error return details.
> 
> Add details for alpha/arc/m68k/microblaze/nios2/powerpc/superh/tile/xtensa.
> 
> Signed-off-by: Mike Frysinger <vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>

Great stuff! Thanks, Mike. Applied. (But afterward, I tweaked things a
little so the table was not so wide.)

Cheers,

Michael


> ---
>  man2/syscall.2 | 77 ++++++++++++++++++++++++++++++++++++++++------------------
>  1 file changed, 53 insertions(+), 24 deletions(-)
> 
> diff --git a/man2/syscall.2 b/man2/syscall.2
> index ee87416..d35f1ef 100644
> --- a/man2/syscall.2
> +++ b/man2/syscall.2
> @@ -150,47 +150,67 @@ The first table lists the instruction used to transition to kernel mode,
>  so you might have to refer to
>  .BR vdso (7)),
>  the register used to indicate the system call number,
> -and the register used to return the system call result.
> +the register used to return the system call result,
> +and the register used to signal an error.
>  .if t \{\
>  .ft CW
>  \}
>  .TS
> -l l1 l l1 l.
> -arch/ABI	instruction	syscall #	retval	Notes
> +l	l	l	l	l	l.
> +arch/ABI	instruction	syscall #	retval	error	Notes
>  _
> -arm/OABI	swi NR	-	a1	NR is syscall #
> -arm/EABI	swi 0x0	r7	r0
> -arm64	svc #0	x8	x0
> -blackfin	excpt 0x0	P0	R0
> -i386	int $0x80	eax	eax
> -ia64	break 0x100000	r15	r8	See below
> -mips	syscall	v0	v0	See below
> -parisc	ble 0x100(%sr2, %r0)	r20	r28
> -s390	svc 0	r1	r2	See below
> -s390x	svc 0	r1	r2	See below
> -sparc/32	t 0x10	g1	o0
> -sparc/64	t 0x6d	g1	o0
> -x86_64	syscall	rax	rax	See below
> -x32	syscall	rax	rax	See below
> +alpha	callsys	v0	a0	a3	See below *
> +arc	trap0	r8	r0	-
> +arm/OABI	swi NR	-	a1	-	NR is syscall #
> +arm/EABI	swi 0x0	r7	r0	-
> +arm64	svc #0	x8	x0	-
> +blackfin	excpt 0x0	P0	R0	-
> +i386	int $0x80	eax	eax	-
> +ia64	break 0x100000	r15	r8	r10	See below *
> +m68k	trap #0	d0	d0	-
> +microblaze	brki r14,8	r12	r3	-
> +mips	syscall	v0	v0	a3	See below *
> +nios2	trap	r2	r2	r7
> +parisc	ble 0x100(%sr2, %r0)	r20	r28	-
> +powerpc	sc	r0	r3	r0	See below *
> +s390	svc 0	r1	r2	-	See below **
> +s390x	svc 0	r1	r2	-	See below **
> +superh	trap #0x17	r3	r0	-	See below ****
> +sparc/32	t 0x10	g1	o0	psr/csr	See below *
> +sparc/64	t 0x6d	g1	o0	psr/csr	See below *
> +tile	swint1	R10	R00	R01	See below *
> +x86_64	syscall	rax	rax	-	See below ***
> +x32	syscall	rax	rax	-	See below ***
> +xtensa	syscall	a2	a2	-
>  .TE
>  .PP
> +*
> +On a few architectures,
> +a register is used as a boolean (0 == no error while -1 == error) to signal the
> +system call failed.
> +The actual error value is still contained in the return register.
> +On sparc, the carry bit (csr) in the processor status register (psr) is used
> +instead of a full register.
> +
> +**
>  For s390 and s390x, NR (the system call number)
>  may be passed directly with "svc NR" if it is less than 256.
>  
> +***
>  The x32 ABI uses the same instruction as the x86_64 ABI and is used on
>  the same processors.
>  To differentiate between them, the bit mask
>  .I __X32_SYSCALL_BIT
>  is bitwise-ORed into the system call number for system calls
>  under the x32 ABI.
> +Both syscall tables are available though, so setting the bit is not a hard
> +requirement.
>  
> -On a few architectures,
> -a register is used to indicate simple boolean failure of the system call:
> -ia64 uses
> -.I r10
> -for this purpose,
> -and mips uses
> -.IR a3 .
> +****
> +On SuperH, the trap number controls the maximum number of args passed.
> +A trap #0x10 can be used with only 0 arg syscalls,
> +a trap #0x11 can be used with 0 or 1 arg syscalls,
> +and so on up to 0x17 for 7 arg syscalls.
>  .if t \{\
>  .in
>  .ft P
> @@ -204,21 +224,30 @@ The second table shows the registers used to pass the system call arguments.
>  l	l2	l2	l2	l2	l2	l2	l2	l.
>  arch/ABI	arg1	arg2	arg3	arg4	arg5	arg6	arg7	Notes
>  _
> +alpha	a0	a1	a2	a3	a4	a5	-
> +arc	r0	r1	r2	r3	r4	r5	-
>  arm/OABI	a1	a2	a3	a4	v1	v2	v3
>  arm/EABI	r0	r1	r2	r3	r4	r5	r6
>  arm64	x0	x1	x2	x3	x4	x5	-
>  blackfin	R0	R1	R2	R3	R4	R5	-
>  i386	ebx	ecx	edx	esi	edi	ebp	-
>  ia64	out0	out1	out2	out3	out4	out5	-
> +m68k	d1	d2	d3	d4	d5	a0	-
> +microblaze	r5	r6	r7	r8	r9	r10	-
>  mips/o32	a0	a1	a2	a3	-	-	-	See below
>  mips/n32,64	a0	a1	a2	a3	a4	a5	-
> +nios2	r4	r5	r6	r7	r8	r9	-
>  parisc	r26	r25	r24	r23	r22	r21	-
> +powerpc	r3	r4	r5	r6	r7	r8	r9
>  s390	r2	r3	r4	r5	r6	r7	-
>  s390x	r2	r3	r4	r5	r6	r7	-
> +superh	r4	r5	r6	r7	r0	r1	r2
>  sparc/32	o0	o1	o2	o3	o4	o5	-
>  sparc/64	o0	o1	o2	o3	o4	o5	-
> +tile	R00	R01	R02	R03	R04	R05	-
>  x86_64	rdi	rsi	rdx	r10	r8	r9	-
>  x32	rdi	rsi	rdx	r10	r8	r9	-
> +xtensa	a6	a3	a4	a5	a8	a9	-
>  .TE
>  .PP
>  The mips/o32 system call convention passes
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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