Re: Add private syscalls to support NPTL

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Maxim Kuvyrkov wrote:
Maxim Kuvyrkov wrote:

Here is the updated patch.

Hm, I've attached the patch without the unistd.h hunk. Here is the proper one.

Yet, another update patch.  This version fixes several indentation errors.

BTW, Geert, what is the preferred branch in m68k git repository for patches to be sent against? I looked around and 'for-linus' seems to be the most appropriate choice.

--
Maxim K.
CodeSourcery
From 2d7f5332009cf6bbc4029fb62979d0cd19b2e0d9 Mon Sep 17 00:00:00 2001
From: Maxim Kuvyrkov <maxim@xxxxxxxxxxxxxxxx>
Date: Fri, 28 Aug 2009 14:46:21 +0400
Subject: [PATCH] Add syscalls to support m68k NPTL.

This patch adds several syscalls, that provide necessary
functionality to support NPTL on m68k/ColdFire.
The syscalls are read_tp, write_tp, atomic_cmpxchg_32 and atomic_barrier.
The cmpxchg syscall is required for ColdFire as it doesn't support 'cas'
instruction.

Signed-off-by: Maxim Kuvyrkov <maxim@xxxxxxxxxxxxxxxx>
---
 arch/m68k/include/asm/thread_info_mm.h |    1 +
 arch/m68k/include/asm/unistd.h         |    6 ++-
 arch/m68k/kernel/entry.S               |    4 ++
 arch/m68k/kernel/process.c             |    4 ++
 arch/m68k/kernel/sys_m68k.c            |   82 ++++++++++++++++++++++++++++++++
 5 files changed, 96 insertions(+), 1 deletions(-)

diff --git a/arch/m68k/include/asm/thread_info_mm.h b/arch/m68k/include/asm/thread_info_mm.h
index 6ea5c33..c24a353 100644
--- a/arch/m68k/include/asm/thread_info_mm.h
+++ b/arch/m68k/include/asm/thread_info_mm.h
@@ -10,6 +10,7 @@ struct thread_info {
 	struct exec_domain	*exec_domain;	/* execution domain */
 	int			preempt_count;	/* 0 => preemptable, <0 => BUG */
 	__u32 cpu; /* should always be 0 on m68k */
+	unsigned long tp_value;
 	struct restart_block    restart_block;
 };
 
diff --git a/arch/m68k/include/asm/unistd.h b/arch/m68k/include/asm/unistd.h
index 946d869..c035c8b 100644
--- a/arch/m68k/include/asm/unistd.h
+++ b/arch/m68k/include/asm/unistd.h
@@ -336,10 +336,14 @@
 #define __NR_pwritev		330
 #define __NR_rt_tgsigqueueinfo	331
 #define __NR_perf_counter_open	332
+#define __NR_read_tp		333
+#define __NR_write_tp		334
+#define __NR_atomic_cmpxchg_32	335
+#define __NR_atomic_barrier	336
 
 #ifdef __KERNEL__
 
-#define NR_syscalls		333
+#define NR_syscalls		337
 
 #define __ARCH_WANT_IPC_PARSE_VERSION
 #define __ARCH_WANT_OLD_READDIR
diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S
index c3735cd..bd168a1 100644
--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -757,4 +757,8 @@ sys_call_table:
 	.long sys_pwritev		/* 330 */
 	.long sys_rt_tgsigqueueinfo
 	.long sys_perf_counter_open
+	.long sys_read_tp
+	.long sys_write_tp
+	.long sys_atomic_cmpxchg_32	/* 335 */
+	.long sys_atomic_barrier
 
diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index 72bad65..2e0ad07 100644
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -251,6 +251,10 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 
 	p->thread.usp = usp;
 	p->thread.ksp = (unsigned long)childstack;
+
+	if (clone_flags & CLONE_SETTLS)
+		task_thread_info(p)->tp_value = regs->d5;
+
 	/*
 	 * Must save the current SFC/DFC value, NOT the value when
 	 * the parent was last descheduled - RGH  10-08-96
diff --git a/arch/m68k/kernel/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c
index 7f54efa..a56c18f 100644
--- a/arch/m68k/kernel/sys_m68k.c
+++ b/arch/m68k/kernel/sys_m68k.c
@@ -29,6 +29,11 @@
 #include <asm/traps.h>
 #include <asm/page.h>
 #include <asm/unistd.h>
+#include <linux/elf.h>
+#include <asm/tlb.h>
+
+asmlinkage int do_page_fault(struct pt_regs *regs, unsigned long address,
+			unsigned long error_code);
 
 /* common code for old and new mmaps */
 static inline long do_mmap2(
@@ -663,3 +668,80 @@ int kernel_execve(const char *filename, char *const argv[], char *const envp[])
 			: "d" (__a), "d" (__b), "d" (__c));
 	return __res;
 }
+
+asmlinkage unsigned long
+sys_read_tp(void)
+{
+	return current_thread_info()->tp_value;
+}
+
+asmlinkage int
+sys_write_tp(unsigned long tp)
+{
+	current_thread_info()->tp_value = tp;
+	return 0;
+}
+
+/* This syscall gets its arguments in A0 (mem), D2 (oldval) and
+   D1 (newval).  */
+asmlinkage int
+sys_atomic_cmpxchg_32(unsigned long newval, int oldval, int d3, int d4, int d5,
+		unsigned long __user *mem)
+{
+	struct mm_struct *mm = current->mm;
+
+	/* This was borrowed from ARM's implementation.  */
+	for (;;) {
+		pgd_t *pgd; pmd_t *pmd; pte_t *pte;
+		spinlock_t *ptl;
+		unsigned long mem_value;
+
+		down_read(&mm->mmap_sem);
+		pgd = pgd_offset(mm, (unsigned long)mem);
+		if (!pgd_present(*pgd))
+			goto bad_access;
+		pmd = pmd_offset(pgd, (unsigned long)mem);
+		if (!pmd_present(*pmd))
+			goto bad_access;
+		pte = pte_offset_map_lock(mm, pmd, (unsigned long)mem, &ptl);
+		if (!pte_present(*pte) || !pte_dirty(*pte)) {
+			pte_unmap_unlock(pte, ptl);
+			goto bad_access;
+		}
+
+		mem_value = *mem;
+		if (mem_value == oldval)
+			*mem = newval;
+
+		pte_unmap_unlock(pte, ptl);
+		up_read(&mm->mmap_sem);
+		return mem_value;
+
+bad_access:
+		up_read(&mm->mmap_sem);
+		/* This is not necessarily a bad access, we can get here if
+		   a memory we're trying to write to should be copied-on-write.
+		   Make the kernel do the necessary page stuff, then re-iterate.
+		   Simulate a write access fault to do that.  */
+		{
+			/* The first argument of the function corresponds to
+			   D1, which is the first field of struct pt_regs.  */
+			struct pt_regs *fp = (struct pt_regs *)&newval;
+
+			/* '3' is an RMW flag.  */
+			if (do_page_fault(fp, (unsigned long)mem, 3))
+				/* If the do_page_fault() failed, we don't
+				   have anything meaningful to return.
+				   There should be a SIGSEGV pending for
+				   the process.  */
+				return 0xdeadbeef;
+		}
+	}
+}
+
+asmlinkage int
+sys_atomic_barrier(void)
+{
+	/* no code needed for uniprocs */
+	return 0;
+}
-- 
1.6.4


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