Patchwork [v2,16/21] nptl: sparc: Fix Race conditions in pthread cancellation (BZ#12683)

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Submitter Adhemerval Zanella Netto
Date Feb. 26, 2018, 9:03 p.m.
Message ID <1519679016-12241-17-git-send-email-adhemerval.zanella@linaro.org>
Download mbox | patch
Permalink /patch/26092/
State New
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Comments

Adhemerval Zanella Netto - Feb. 26, 2018, 9:03 p.m.
This patch adds the sparc modifications required for the BZ#12683.
It basically adds the required ucontext_get_pc function, cancellable
syscall wrappers, and a fix for pause.

Sparc requires arch-specific syscall_cancel implementation because
INLINE_SYSCALL_NCS uses the __SYSCALL_STRING (defined different
for sparc32 and sparc64) and it issues additional instructions
after the syscall one to check the resulting error code.  When used
in the default syscall_cancel.c implementation the label
__syscall_cancel_arch_end is not placed just after the syscall as
expected.  Both 32 and 64 bits version were based on default C version
built with GCC 6.1.

Also, different than other architectures, SPARC passes the sigcontext_t
struct pointer as third argument in the signal handler set with
SA_SIGINFO (some info at [1]) for 64 bits and the pt_regs in 32 bits.
From Linux code:

* arch/sparc/kernel/signal_64.c

428         /* 3. signal handler back-trampoline and parameters */
429         regs->u_regs[UREG_FP] = ((unsigned long) sf) - STACK_BIAS;
430         regs->u_regs[UREG_I0] = ksig->sig;
431         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
432
433         /* The sigcontext is passed in this way because of how it
434          * is defined in GLIBC's /usr/include/bits/sigcontext.h
435          * for sparc64.  It includes the 128 bytes of siginfo_t.
436          */
437         regs->u_regs[UREG_I2] = (unsigned long) &sf->info;

* arch/sparc/kernel/signal_32.c:

392         regs->u_regs[UREG_FP] = (unsigned long) sf;
393         regs->u_regs[UREG_I0] = ksig->sig;
394         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
395         regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
396
397         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
398         regs->npc = (regs->pc + 4);

So to access the signal mask in the signal frame, a arch-specific
ucontext_get_mask is defined which obtain the sa_mask from the context.

Checked on a SPARC T5 for sparc64-linux-gnu and sparcv9-linux-gnu.

	[BZ #12683]
	* sysdeps/unix/sysv/linux/sparc/sparc32/sigcontextinfo.h
	(ucontext_get_pc): New function.
	* sysdeps/unix/sysv/linux/sparc/sparc64/sigcontextinfo.h
	(ucontext_get_pc): Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S: New file.
	* sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S: Likwise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/pause.c: New file.

[1] https://www.spinics.net/lists/sparclinux/msg05037.html
---
 ChangeLog                                          |  9 +++
 sysdeps/unix/sysv/linux/sparc/lowlevellock.h       |  2 +-
 .../unix/sysv/linux/sparc/sparc32/sigcontextinfo.h | 52 +++++++++++++++
 .../unix/sysv/linux/sparc/sparc32/syscall_cancel.S | 74 ++++++++++++++++++++++
 sysdeps/unix/sysv/linux/sparc/sparc64/pause.c      | 25 ++++++++
 .../unix/sysv/linux/sparc/sparc64/sigcontextinfo.h | 40 ++++++++++++
 .../unix/sysv/linux/sparc/sparc64/syscall_cancel.S | 74 ++++++++++++++++++++++
 7 files changed, 275 insertions(+), 1 deletion(-)
 create mode 100644 sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S
 create mode 100644 sysdeps/unix/sysv/linux/sparc/sparc64/pause.c
 create mode 100644 sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S

Patch

diff --git a/sysdeps/unix/sysv/linux/sparc/lowlevellock.h b/sysdeps/unix/sysv/linux/sparc/lowlevellock.h
index e2c0b2a..ed2e746 100644
--- a/sysdeps/unix/sysv/linux/sparc/lowlevellock.h
+++ b/sysdeps/unix/sysv/linux/sparc/lowlevellock.h
@@ -117,7 +117,7 @@  __lll_timedlock (int *futex, const struct timespec *abstime, int private)
     {							\
       __typeof (tid) __tid;				\
       while ((__tid = (tid)) != 0)			\
-	lll_futex_wait (&(tid), __tid, LLL_SHARED);	\
+	lll_futex_wait_cancel (&(tid), __tid, LLL_SHARED); \
     }							\
   while (0)
 
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/sigcontextinfo.h b/sysdeps/unix/sysv/linux/sparc/sparc32/sigcontextinfo.h
index 91233b8..4114035 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/sigcontextinfo.h
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/sigcontextinfo.h
@@ -16,6 +16,11 @@ 
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _SIGCONTEXTINFO_H
+#define _SIGCONTEXTINFO_H
+
+#include <stdint.h>
+
 #define SIGCONTEXT struct sigcontext *
 #define SIGCONTEXT_EXTRA_ARGS
 #define GET_PC(__ctx)	((void *) ((__ctx)->si_regs.pc))
@@ -29,3 +34,50 @@ 
 #define GET_FRAME(__ctx)	ADVANCE_STACK_FRAME (GET_STACK(__ctx))
 #define CALL_SIGHANDLER(handler, signo, ctx) \
   (handler)((signo), SIGCONTEXT_EXTRA_ARGS (ctx))
+
+/* Different that other architectures, SPARC32 pass a pt_regs (or pt_regs32
+   in 32 bits compat mode) struct pointer as third argument for sa_sigaction
+   handler with SA_SIGINFO.
+
+   Also current sparc32 rt signal frame layout is:
+
+   field                                  | size
+   ---------------------------------------| ----
+   struct rt_signal_frame {               |
+     struct sparc_stackf     ss;          |  96
+     siginfo_t               info;        | 128
+     struct pt_regs          regs;        |  80
+     sigset_t                mask;        | 128
+     __siginfo_fpu_t __user  *fpu_save;   |   4
+     unsigned int            insns[2];    |   8
+     stack_t                 stack;       |  12
+     unsigned int            extra_size;  |   4
+     __siginfo_rwin_t __user *rwin_save;  |   4
+   };
+
+   So to obtain a pointer to signal mask based on address of pt_regs
+   we need to add 208.  */
+
+struct pt_regs32
+{
+   unsigned int psr;
+   unsigned int pc;
+   unsigned int npc;
+   unsigned int y;
+   unsigned int u_regs[16];
+};
+
+static inline uintptr_t
+ucontext_get_pc (struct pt_regs32 *regs)
+{
+  return regs->pc;
+}
+
+static inline sigset_t *
+ucontext_get_mask (const void *ctx)
+{
+  return (sigset_t *)((uintptr_t)ctx + 208);
+}
+#define UCONTEXT_SIGMASK(ctx) ucontext_get_mask (ctx)
+
+#endif /* _SIGCONTEXTINFO_H  */
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S b/sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S
new file mode 100644
index 0000000..c06f9d1
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S
@@ -0,0 +1,74 @@ 
+/* Cancellable syscall wrapper.  Linux/sparc32 version.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+/* long int __syscall_cancel_arch (int *cancelhandling,
+				   long int nr,
+				   long int arg1,
+				   long int arg2,
+				   long int arg3,
+				   long int arg4,
+				   long int arg5,
+				   long int arg6)  */
+
+ENTRY (__syscall_cancel_arch)
+	save	%sp, -104, %sp
+
+	cfi_window_save
+	cfi_register (15, 31)
+	cfi_def_cfa_register (30)
+
+	.globl __syscall_cancel_arch_start
+__syscall_cancel_arch_start:
+
+	/* if (*cancelhandling & CANCELED_BITMASK)
+	     __syscall_do_cancel()  */
+	ld	[%i0], %g2
+	andcc	%g2, 4, %g0
+	bne,pn	%icc, 2f
+
+	/* Issue a 6 argument syscall.  */
+	mov	%i1, %g1
+	mov	%i2, %o0
+	mov	%i3, %o1
+	mov	%i4, %o2
+	mov	%i5, %o3
+	ld	[%fp+92], %o4
+	ld	[%fp+96], %o5
+	ta	0x10
+
+	.globl __syscall_cancel_arch_end
+__syscall_cancel_arch_end:
+	bcc	1f
+	mov	0,%g1
+	sub	%g0, %o0, %o0
+	mov	1, %g1
+
+1:
+	mov	%o0, %i0
+	return	%i7+8
+	 nop
+
+2:
+	call	__syscall_do_cancel, 0
+	 nop
+	nop
+
+END (__syscall_cancel_arch)
+libc_hidden_def (__syscall_cancel_arch)
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/pause.c b/sysdeps/unix/sysv/linux/sparc/sparc64/pause.c
new file mode 100644
index 0000000..4a0cf4d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/pause.c
@@ -0,0 +1,25 @@ 
+/* Linux pause syscall implementation.  Linux/sparc64.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sys/syscall.h>
+
+/* On sparc interrupted pause syscall returns with a PC indicating a
+   side-effect and this deviates from other architectures.  Fall back to
+   ppool implementation.  */
+#undef __NR_pause
+#include <sysdeps/unix/sysv/linux/pause.c>
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/sigcontextinfo.h b/sysdeps/unix/sysv/linux/sparc/sparc64/sigcontextinfo.h
index c9d2685..dc04c42 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/sigcontextinfo.h
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/sigcontextinfo.h
@@ -16,6 +16,11 @@ 
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _SIGCONTEXTINFO_H
+#define _SIGCONTEXTINFO_H
+
+#include <stdint.h>
+
 #ifndef STACK_BIAS
 #define STACK_BIAS 2047
 #endif
@@ -29,3 +34,38 @@ 
 #define GET_FRAME(__ctx)	ADVANCE_STACK_FRAME (GET_STACK (__ctx))
 #define CALL_SIGHANDLER(handler, signo, ctx) \
   (handler)((signo), SIGCONTEXT_EXTRA_ARGS (ctx))
+
+/* Different that other architectures, SPARC64 pass a sigcontext_t struct
+   pointer in third argument for sa_sigaction handler with SA_SIGINFO.
+
+   Also current sparc64 rt signal frame layout is:
+
+   field                                  | size
+   ---------------------------------------| ----
+   struct rt_signal_frame {               |
+      struct sparc_stackf     ss;         | 192
+      siginfo_t               info;       | 128
+      struct pt_regs          regs;       | 160
+      __siginfo_fpu_t __user  *fpu_save;  |   8
+      stack_t                 stack;      |  24
+      sigset_t                mask;       | 128
+      __siginfo_rwin_t        *rwin_save; |   8
+   };
+
+   So to obtain a pointer to signal mask based on address of info
+   we need to add 320.  */
+
+static inline uintptr_t
+ucontext_get_pc (const struct sigcontext *sigctx)
+{
+  return sigctx->sigc_regs.tpc;
+}
+
+static inline sigset_t *
+ucontext_get_mask (const void *ctx)
+{
+  return (sigset_t *)((uintptr_t)ctx + 320);
+}
+#define UCONTEXT_SIGMASK(ctx) ucontext_get_mask (ctx)
+
+#endif /* _SIGCONTEXTINFO_H  */
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S b/sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S
new file mode 100644
index 0000000..f3eef78
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S
@@ -0,0 +1,74 @@ 
+/* Cancellable syscall wrapper.  Linux/sparc64 version.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+/* long int __syscall_cancel_arch (int *cancelhandling,
+					long int nr,
+					long int arg1,
+					long int arg2,
+					long int arg3,
+					long int arg4,
+					long int arg5,
+					long int arg6)  */
+
+ENTRY (__syscall_cancel_arch)
+	save	%sp, -176, %sp
+
+	cfi_window_save
+	cfi_register (15, 31)
+	cfi_def_cfa_register (30)
+
+	.globl __syscall_cancel_arch_start
+__syscall_cancel_arch_start:
+
+	/* if (*cancelhandling & CANCELED_BITMASK)
+	     __syscall_do_cancel()  */
+	lduw	[%i0], %g1
+	andcc	%g1, 4, %g0
+	bne,pn	%xcc, 2f
+
+	/* Issue a 6 argument syscall.  */
+	mov	%i1, %g1
+	mov	%i2, %o0
+	mov	%i3, %o1
+	mov	%i4, %o2
+	mov	%i5, %o3
+	ldx	[%fp + STACK_BIAS + 176], %o4
+	ldx	[%fp + STACK_BIAS + 184], %o5
+	ta	0x6d
+
+	.global __syscall_cancel_arch_end
+__syscall_cancel_arch_end:
+
+	bcc,pt	%xcc, 1f
+	mov	0, %g1
+	sub	%g0, %o0, %o0
+	mov	1, %g1
+1:
+	mov	%o0, %i0
+	return	%i7+8
+	nop
+
+2:
+	call	__syscall_do_cancel, 0
+	nop
+	nop
+
+END (__syscall_cancel_arch)
+libc_hidden_def (__syscall_cancel_arch)