[PATCH 3/3] 64-bit futexes: x86 support
From: Ulrich Drepper
Date: Fri May 30 2008 - 21:27:55 EST
This patch adds 64-bit futex support for x86. As explained in the
introduction, this requires a new system call. The remaining changes are
similarly to the x86-64 changes: enable support for FUTEX_WAKE_OP.
[Sorry Andrew, but syscalls unfortunately have to be added at the end.
So you'll have to live with the conflicts.]
arch/x86/ia32/ia32entry.S | 1
arch/x86/ia32/sys_ia32.c | 46 ++++++++++++++++++++++++++++++
arch/x86/kernel/sys_i386_32.c | 48 ++++++++++++++++++++++++++++++++
arch/x86/kernel/syscall_table_32.S | 1
include/asm-x86/futex.h | 55 +++++++++++++++++++++++++++++++++++--
include/asm-x86/types.h | 2 -
include/asm-x86/unistd_32.h | 1
scripts/checksyscalls.sh | 1
8 files changed, 151 insertions(+), 4 deletions(-)
Signed-off-by: Ulrich Drepper <drepper@xxxxxxxxxx>
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index b5e329d..776b6a2 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -731,4 +731,5 @@ ia32_sys_call_table:
.quad sys32_fallocate
.quad compat_sys_timerfd_settime /* 325 */
.quad compat_sys_timerfd_gettime
+ .quad sys32_futex64
ia32_syscall_end:
diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
index f00afdf..f5a6403 100644
--- a/arch/x86/ia32/sys_ia32.c
+++ b/arch/x86/ia32/sys_ia32.c
@@ -24,6 +24,7 @@
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
+#include <linux/futex.h>
#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/times.h>
@@ -865,3 +866,48 @@ asmlinkage long sys32_fallocate(int fd, int mode, unsigned offset_lo,
return sys_fallocate(fd, mode, ((u64)offset_hi << 32) | offset_lo,
((u64)len_hi << 32) | len_lo);
}
+
+/* For the futex syscall with 64-bit values we would need more than the six
+ available syscall parameters. Pass the parameters in memory instead. */
+struct futex_arg_struct {
+ u32 uaddr;
+ int op;
+ u64 val;
+ u32 utime;
+ u32 uaddr2;
+ u64 val3;
+};
+
+asmlinkage long sys32_futex64(struct futex_arg_struct __user *arg)
+{
+ struct futex_arg_struct a;
+ struct compat_timespec *utime;
+ struct timespec ts;
+ ktime_t t, *tp = NULL;
+ u32 val2 = 0;
+ int cmd;
+
+ if (copy_from_user(&a, arg, sizeof(a)))
+ return -EFAULT;
+
+ cmd = a.op & FUTEX_CMD_MASK;
+ utime = (struct compat_timespec __user *) (u64) a.utime;
+
+ if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
+ cmd == FUTEX_WAIT_BITSET)) {
+ if (get_compat_timespec(&ts, utime))
+ return -EFAULT;
+ if (!timespec_valid(&ts))
+ return -EINVAL;
+
+ t = timespec_to_ktime(ts);
+ if (cmd == FUTEX_WAIT)
+ t = ktime_add_safe(ktime_get(), t);
+ tp = &t;
+ }
+ if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE)
+ val2 = a.utime;
+
+ return do_futex((void __user *) (u64) a.uaddr, a.op, a.val, tp,
+ (void __user *) (u64) a.uaddr2, val2, a.val3);
+}
diff --git a/arch/x86/kernel/sys_i386_32.c b/arch/x86/kernel/sys_i386_32.c
index d2ab52c..a28da03 100644
--- a/arch/x86/kernel/sys_i386_32.c
+++ b/arch/x86/kernel/sys_i386_32.c
@@ -244,3 +244,51 @@ int kernel_execve(const char *filename, char *const argv[], char *const envp[])
: "0" (__NR_execve),"ri" (filename),"c" (argv), "d" (envp) : "memory");
return __res;
}
+
+
+/* For the futex syscall with 64-bit values we would need more than the six
+ available syscall parameters. Pass the parameters in memory instead. */
+struct futex_arg_struct {
+ void __user *uaddr;
+ int op;
+ u64 val;
+ struct timespec __user *utime;
+ void __user *uaddr2;
+ u64 val3;
+};
+
+asmlinkage long sys_futex64(struct futex_arg_struct __user *arg)
+{
+ struct futex_arg_struct a;
+ struct timespec ts;
+ ktime_t t, *tp = NULL;
+ u32 val2 = 0;
+ int cmd;
+
+ if (copy_from_user(&a, arg, sizeof(a)))
+ return -EFAULT;
+
+ cmd = a.op & FUTEX_CMD_MASK;
+
+ if (a.utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
+ cmd == FUTEX_WAIT_BITSET)) {
+ if (copy_from_user(&ts, a.utime, sizeof(ts)) != 0)
+ return -EFAULT;
+ if (!timespec_valid(&ts))
+ return -EINVAL;
+
+ t = timespec_to_ktime(ts);
+ if (cmd == FUTEX_WAIT)
+ t = ktime_add_safe(ktime_get(), t);
+ tp = &t;
+ }
+ /*
+ * requeue parameter in 'utime' if cmd == FUTEX_REQUEUE.
+ * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP.
+ */
+ if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
+ cmd == FUTEX_WAKE_OP)
+ val2 = (u32) (unsigned long) a.utime;
+
+ return do_futex(a.uaddr, a.op, a.val, tp, a.uaddr2, val2, a.val3);
+}
diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
index adff556..5b1b5d9 100644
--- a/arch/x86/kernel/syscall_table_32.S
+++ b/arch/x86/kernel/syscall_table_32.S
@@ -326,3 +326,4 @@ ENTRY(sys_call_table)
.long sys_fallocate
.long sys_timerfd_settime /* 325 */
.long sys_timerfd_gettime
+ .long sys_futex64
diff --git a/include/asm-x86/unistd_32.h b/include/asm-x86/unistd_32.h
index 8317d94..8be8e19 100644
--- a/include/asm-x86/unistd_32.h
+++ b/include/asm-x86/unistd_32.h
@@ -332,6 +332,7 @@
#define __NR_fallocate 324
#define __NR_timerfd_settime 325
#define __NR_timerfd_gettime 326
+#define __NR_futex64 327
#ifdef __KERNEL__
diff --git a/scripts/checksyscalls.sh b/scripts/checksyscalls.sh
index 366f8c7..a03b34c 100755
--- a/scripts/checksyscalls.sh
+++ b/scripts/checksyscalls.sh
@@ -98,6 +98,7 @@ cat << EOF
#define __IGNORE_setgid32
#define __IGNORE_setfsuid32
#define __IGNORE_setfsgid32
+#define __IGNORE_futex64
/* sync_file_range had a stupid ABI. Allow sync_file_range2 instead */
#ifdef __NR_sync_file_range2
--- a/include/asm-x86/types.h 2008-05-28 15:57:16.000000000 -0700
+++ b/include/asm-x86/types.h 2008-05-28 15:57:39.000000000 -0700
@@ -30,10 +30,8 @@
typedef u32 dma_addr_t;
#endif
-#ifdef CONFIG_X86_64
typedef u64 futex_val_t;
#define __have_futex_val_t
-#endif
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
--- a/include/asm-x86/futex.h 2008-05-28 16:09:03.000000000 -0700
+++ b/include/asm-x86/futex.h 2008-05-28 16:09:20.000000000 -0700
@@ -46,7 +46,34 @@
oldval = oldvaltemp; \
} while (0)
-#ifndef CONFIG_X86_32
+#ifdef CONFIG_X86_32
+#define __futex_atomic64_op(insns, ret, oldval, uaddr, oparg) \
+ do { \
+ u32 oldvaltemp1, oldvaltemp2; \
+ int tem2; \
+ asm volatile("1:\tmovl %3, %0\n" \
+ "2:\tmovl %4, %1\n" \
+ "\tmovl\t%0, %5\n" \
+ "\tmovl\t%1, %6\n" \
+ "\t" insns "\n" \
+ "3:\tlock; cmpxchg8b %3\n" \
+ "\tjnz\t1b\n" \
+ "4:\t.section .fixup,\"ax\"\n" \
+ "5:\tmov\t%5, %1\n" \
+ "\tjmp\t4b\n" \
+ "\t.previous\n" \
+ _ASM_EXTABLE(1b, 5b) \
+ _ASM_EXTABLE(2b, 5b) \
+ _ASM_EXTABLE(3b, 5b) \
+ : "=&a" (oldvaltemp1), "=&d" (oldvaltmep2),\
+ "=&r" (ret), \
+ "+m" (((u32 __user *) uaddr)[0]), \
+ "+m" (((u32 __user *) uaddr)[1]), \
+ "=&b" (tem), "=&c" (tem2) \
+ : "r" (oparg), "i" (-EFAULT), "2" (0)); \
+ oldval = (((u64) oldvaltemp2) << 32) | oldvaltemp1; \
+ } while (0)
+#else
#define __futex_atomic64_op1(insn, ret, oldval, uaddr, oparg) \
asm volatile("1:\t" insn "\n" \
"2:\t.section .fixup,\"ax\"\n" \
@@ -97,6 +124,12 @@ static inline int futex_atomic_op_inuser
if (op != FUTEX_OP_SET && boot_cpu_data.x86 == 3)
return -ENOSYS;
#endif
+#ifdef CONFIG_X86_32
+ /* Not all 32-bit machines support 8-byte cmpxchg. We just
+ unconditionally perform a runtime check for the feature. */
+ if ((op & FUTEX_FLAG_64) && !boot_cpu_has(X86_FEATURE_CX8))
+ return -ENOSYS;
+#endif
pagefault_disable();
@@ -117,7 +150,25 @@ static inline int futex_atomic_op_inuser
case FUTEX_OP_XOR:
__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
break;
-#ifndef CONFIG_X86_32
+#ifdef CONFIG_X86_32
+ case FUTEX_OP64_SET:
+ __futex_atomic64_op("movl %7, %5\n\txorl %6, %6",
+ ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP64_ADD:
+ __futex_atomic64_op("addl %7, %5\n\tadcl $0, %6", ret, oldval,
+ uaddr, oparg);
+ break;
+ case FUTEX_OP64_OR:
+ __futex_atomic64_op("orl %7, %5", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP64_ANDN:
+ __futex_atomic64_op("andl %7, %5", ret, oldval, uaddr, ~oparg);
+ break;
+ case FUTEX_OP64_XOR:
+ __futex_atomic64_op("xorl %7, %5", ret, oldval, uaddr, oparg);
+ break;
+#else
case FUTEX_OP64_SET:
__futex_atomic64_op1("xchgq %q0, %q2",
ret, oldval, uaddr, oparg);
--
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