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alpha: use alpha_ni_syscall only for syscall zero

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Once upon a time it used to have a C part that printed a warning
about unimplemented OSF syscalls.  That's what it's been doing
all over the OSF syscall range, while the native Linux syscall
range uses sys_ni_syscall().

With those warnings about unimplemented OSF syscalls gone (circa 2.4),
alpha_ni_syscall() has shrunk to that little bit of asm and the
only reason it hasn't been replaced with sys_ni_syscall() everywhere
is that extra twist needed in case of syscall #0.

Let's keep it only for syscall #0 and replace the rest with sys_ni_syscall.
And use sys_ni_syscall for "number out range" in ptraced-call case, as
we'd been doing for normal codepath since 2.1.86...

Acked-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2018-08-11 01:04:55 +01:00
committed by Al Viro
parent 5c60a7389d
commit 060581c158
2 changed files with 173 additions and 168 deletions
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23
arch/alpha/kernel/entry.S
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@@ -473,7 +473,7 @@ entSys:
bne $3, strace
beq $4, 1f
ldq $27, 0($5)
1: jsr $26, ($27), alpha_ni_syscall
1: jsr $26, ($27), sys_ni_syscall
ldgp $gp, 0($26)
blt $0, $syscall_error /* the call failed */
stq $0, 0($sp)
@@ -587,7 +587,7 @@ strace:
/* get the system call pointer.. */
lda $1, NR_SYSCALLS($31)
lda $2, sys_call_table
lda $27, alpha_ni_syscall
lda $27, sys_ni_syscall
cmpult $0, $1, $1
s8addq $0, $2, $2
beq $1, 1f
@@ -843,15 +843,20 @@ sys_rt_sigreturn:
.end sys_rt_sigreturn
.align 4
.globl alpha_ni_syscall
.ent alpha_ni_syscall
alpha_ni_syscall:
.globl alpha_syscall_zero
.ent alpha_syscall_zero
alpha_syscall_zero:
.prologue 0
/* Special because it also implements overflow handling via
syscall number 0. And if you recall, zero is a special
trigger for "not an error". Store large non-zero there. */
/* Special because it needs to do something opposite to
force_successful_syscall_return(). We use the saved
syscall number for that, zero meaning "not an error".
That works nicely, but for real syscall 0 we need to
make sure that this logics doesn't get confused.
Store a non-zero there - -ENOSYS we need in register
for our return value will do just fine.
*/
lda $0, -ENOSYS
unop
stq $0, 0($sp)
ret
.end alpha_ni_syscall
.end alpha_syscall_zero