linux/arch/sparc/lib/locks.S

/*
 * locks.S: SMP low-level lock primitives on Sparc.
 *
 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
 * Copyright (C) 1998 Anton Blanchard (anton@progsoc.uts.edu.au)
 * Copyright (C) 1998 Jakub Jelinek   (jj@ultra.linux.cz)
 */

#include <asm/ptrace.h>
#include <asm/psr.h>
#include <asm/smp.h>
#include <asm/spinlock.h>

	.text
	.align	4

	/* Read/writer locks, as usual this is overly clever to make it
	 * as fast as possible.
	 */

	/* caches... */
___rw_read_enter_spin_on_wlock:
	orcc	%g2, 0x0, %g0
	be,a	___rw_read_enter
	 ldstub	[%g1 + 3], %g2
	b	___rw_read_enter_spin_on_wlock
	 ldub	[%g1 + 3], %g2
___rw_read_try_spin_on_wlock:
	andcc	%g2, 0xff, %g0
	be,a	___rw_read_try
	 ldstub	[%g1 + 3], %g2
	xnorcc	%g2, 0x0, %o0	/* if g2 is ~0, set o0 to 0 and bugger off */
	bne,a	___rw_read_enter_spin_on_wlock
	 ld	[%g1], %g2
	retl
	 mov	%g4, %o7
___rw_read_exit_spin_on_wlock:
	orcc	%g2, 0x0, %g0
	be,a	___rw_read_exit
	 ldstub	[%g1 + 3], %g2
	b	___rw_read_exit_spin_on_wlock
	 ldub	[%g1 + 3], %g2
___rw_write_enter_spin_on_wlock:
	orcc	%g2, 0x0, %g0
	be,a	___rw_write_enter
	 ldstub	[%g1 + 3], %g2
	b	___rw_write_enter_spin_on_wlock
	 ld	[%g1], %g2

	.globl	___rw_read_enter
___rw_read_enter:
	orcc	%g2, 0x0, %g0
	bne,a	___rw_read_enter_spin_on_wlock
	 ldub	[%g1 + 3], %g2
	ld	[%g1], %g2
	add	%g2, 1, %g2
	st	%g2, [%g1]
	retl
	 mov	%g4, %o7

	.globl	___rw_read_exit
___rw_read_exit:
	orcc	%g2, 0x0, %g0
	bne,a	___rw_read_exit_spin_on_wlock
	 ldub	[%g1 + 3], %g2
	ld	[%g1], %g2
	sub	%g2, 0x1ff, %g2
	st	%g2, [%g1]
	retl
	 mov	%g4, %o7

	.globl	___rw_read_try
___rw_read_try:
	orcc	%g2, 0x0, %g0
	bne	___rw_read_try_spin_on_wlock
	 ld	[%g1], %g2
	add	%g2, 1, %g2
	st	%g2, [%g1]
	set	1, %o1
	retl
	 mov	%g4, %o7

	.globl	___rw_write_enter
___rw_write_enter:
	orcc	%g2, 0x0, %g0
	bne	___rw_write_enter_spin_on_wlock
	 ld	[%g1], %g2
	andncc	%g2, 0xff, %g0
	bne,a	___rw_write_enter_spin_on_wlock
	 stb	%g0, [%g1 + 3]
	retl
	 mov	%g4, %o7
sparc: remove CVS keywords This patch removes the CVS keywords that weren't updated for a long time from comments. Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> 2008-05-20 03:53:02 +04:00			`/*`
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! 2005-04-17 02:20:36 +04:00			`* locks.S: SMP low-level lock primitives on Sparc.`
			`*`
			`* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)`
			`* Copyright (C) 1998 Anton Blanchard (anton@progsoc.uts.edu.au)`
			`* Copyright (C) 1998 Jakub Jelinek (jj@ultra.linux.cz)`
			`*/`

			`#include <asm/ptrace.h>`
			`#include <asm/psr.h>`
			`#include <asm/smp.h>`
			`#include <asm/spinlock.h>`

			`.text`
			`.align 4`

			`/* Read/writer locks, as usual this is overly clever to make it`
			`* as fast as possible.`
			`*/`

			`/* caches... */`
			`___rw_read_enter_spin_on_wlock:`
			`orcc %g2, 0x0, %g0`
			`be,a ___rw_read_enter`
			`ldstub [%g1 + 3], %g2`
			`b ___rw_read_enter_spin_on_wlock`
			`ldub [%g1 + 3], %g2`
[PATCH] sparc32 rwlock fix read_trylock() is broken on sparc32 (doesn't build and didn't work right, actually). Proposed fix: - make "writer holds lock" distinguishable from "reader tries to grab lock" - have __raw_read_trylock() try to acquire the mutex (in LSB of lock), terminating spin if we see that there's writer holding it. Then do the rest as we do in read_lock(). Thanks to Ingo for discussion... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org> 2006-10-08 17:32:15 +04:00			`___rw_read_try_spin_on_wlock:`
			`andcc %g2, 0xff, %g0`
			`be,a ___rw_read_try`
			`ldstub [%g1 + 3], %g2`
			`xnorcc %g2, 0x0, %o0 /* if g2 is ~0, set o0 to 0 and bugger off */`
			`bne,a ___rw_read_enter_spin_on_wlock`
			`ld [%g1], %g2`
			`retl`
			`mov %g4, %o7`
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! 2005-04-17 02:20:36 +04:00			`___rw_read_exit_spin_on_wlock:`
			`orcc %g2, 0x0, %g0`
			`be,a ___rw_read_exit`
			`ldstub [%g1 + 3], %g2`
			`b ___rw_read_exit_spin_on_wlock`
			`ldub [%g1 + 3], %g2`
			`___rw_write_enter_spin_on_wlock:`
			`orcc %g2, 0x0, %g0`
			`be,a ___rw_write_enter`
			`ldstub [%g1 + 3], %g2`
			`b ___rw_write_enter_spin_on_wlock`
			`ld [%g1], %g2`

			`.globl ___rw_read_enter`
			`___rw_read_enter:`
			`orcc %g2, 0x0, %g0`
			`bne,a ___rw_read_enter_spin_on_wlock`
			`ldub [%g1 + 3], %g2`
			`ld [%g1], %g2`
			`add %g2, 1, %g2`
			`st %g2, [%g1]`
			`retl`
			`mov %g4, %o7`

			`.globl ___rw_read_exit`
			`___rw_read_exit:`
			`orcc %g2, 0x0, %g0`
			`bne,a ___rw_read_exit_spin_on_wlock`
			`ldub [%g1 + 3], %g2`
			`ld [%g1], %g2`
			`sub %g2, 0x1ff, %g2`
			`st %g2, [%g1]`
			`retl`
			`mov %g4, %o7`

[PATCH] sparc32 rwlock fix read_trylock() is broken on sparc32 (doesn't build and didn't work right, actually). Proposed fix: - make "writer holds lock" distinguishable from "reader tries to grab lock" - have __raw_read_trylock() try to acquire the mutex (in LSB of lock), terminating spin if we see that there's writer holding it. Then do the rest as we do in read_lock(). Thanks to Ingo for discussion... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org> 2006-10-08 17:32:15 +04:00			`.globl ___rw_read_try`
			`___rw_read_try:`
			`orcc %g2, 0x0, %g0`
			`bne ___rw_read_try_spin_on_wlock`
			`ld [%g1], %g2`
			`add %g2, 1, %g2`
			`st %g2, [%g1]`
			`set 1, %o1`
			`retl`
			`mov %g4, %o7`

Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! 2005-04-17 02:20:36 +04:00			`.globl ___rw_write_enter`
			`___rw_write_enter:`
			`orcc %g2, 0x0, %g0`
			`bne ___rw_write_enter_spin_on_wlock`
			`ld [%g1], %g2`
			`andncc %g2, 0xff, %g0`
			`bne,a ___rw_write_enter_spin_on_wlock`
			`stb %g0, [%g1 + 3]`
			`retl`
			`mov %g4, %o7`