Re: Add private syscalls to support NPTL

Maxim Kuvyrkov
2009-08-25T19:43:17Z

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Maxim Kuvyrkov wrote:

> Here is the updated patch.

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

--
Maxim K.
CodeSourcery

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From 828160ab5d329e15543a50d0b50ce50f2975966b Mon Sep 17 00:00:00 2001
From: Maxim Kuvyrkov <maxim@codesourcery.com>
Date: Tue, 25 Aug 2009 23:37:26 +0400
Subject: [PATCH] Add syscalls to support m68k NPTL.

This patch adds several syscalls, private to M68K, that provide necessary
functionality to support NPTL.
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@codesourcery.com>
---
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/sys_m68k.c | 82 ++++++++++++++++++++++++++++++++
4 files changed, 92 insertions(+), 1 deletions(-)

diff --git a/arch/m68k/include/asm/thread_info_mm.h b/arch/m68k/include/asm/thread_info_mm.h
index af0fda4..a240244 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..e2a245f 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/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c
index 7f54efa..03651e5 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