From 5232b909bf31420497ec864e34f806a545017185 Mon Sep 17 00:00:00 2001
From: Richard Henderson <rth@twiddle.net>
Date: Wed, 13 Feb 2013 20:10:45 -0800
Subject: [PATCH] arm: Introduce and use GET_TLS

Factor out the sequence needed to call kuser_get_tls, as we can't
play subtract into pc games in thumb mode.  Prepare for hard-tp,
pulling the save of LR into the macro.
---
 ports/ChangeLog.arm                           | 13 ++++++++
 ports/sysdeps/arm/dl-tlsdesc.S                | 13 ++------
 ports/sysdeps/arm/sysdep.h                    | 19 ++++++++++++
 ports/sysdeps/unix/arm/sysdep.S               | 12 ++------
 .../unix/sysv/linux/arm/aeabi_read_tp.S       |  6 ++++
 ports/sysdeps/unix/sysv/linux/arm/clone.S     |  4 +--
 .../unix/sysv/linux/arm/nptl/pt-vfork.S       | 10 +------
 .../unix/sysv/linux/arm/nptl/sysdep-cancel.h  |  2 +-
 .../sysdeps/unix/sysv/linux/arm/nptl/vfork.S  | 10 +------
 ports/sysdeps/unix/sysv/linux/arm/sysdep.h    | 30 +++++++++++++++++++
 10 files changed, 77 insertions(+), 42 deletions(-)

diff --git a/ports/ChangeLog.arm b/ports/ChangeLog.arm
index b5c9ef3347..3ad5704e2f 100644
--- a/ports/ChangeLog.arm
+++ b/ports/ChangeLog.arm
@@ -1,5 +1,18 @@
 2013-03-06  Richard Henderson <rth@redhat.com>
 
+	* sysdeps/arm/sysdep.h (GET_TLS): New macro.
+	* sysdeps/arm/dl-tlsdesc.S (_dl_tlsdesc_undefweak): Use it.
+	(_dl_tlsdesc_dynamic): Likewise.
+	* sysdeps/unix/arm/sysdep.S (__syscall_error): Likewise.
+	* sysdeps/unix/sysv/linux/arm/sysdep.h (GET_TLS): New macro.
+	* sysdeps/unix/sysv/linux/arm/clone.S (__clone): Likewise.
+	* sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S (SAVE_PID): Likewise.
+	* sysdeps/unix/sysv/linux/arm/nptl/vfork.S (SAVE_PID): Likewise.
+	* sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h (SINGLE_THREAD_P):
+	Likewise.
+	* sysdeps/unix/sysv/linux/arm/aeabi_read_tp.S (__aeabi_read_tp):
+	Add thumb2 alternative.
+
 	* sysdeps/arm/sysdep.h (NEGOFF_ADJ_BASE): New macro.
 	(NEGOFF_ADJ_BASE2, NEGOFF_OFF1, NEGOFF_OFF2): New macros.
 	* sysdeps/unix/sysv/linux/arm/clone.S (__clone): Use them.
diff --git a/ports/sysdeps/arm/dl-tlsdesc.S b/ports/sysdeps/arm/dl-tlsdesc.S
index 7b4c8dfcb5..1a15272821 100644
--- a/ports/sysdeps/arm/dl-tlsdesc.S
+++ b/ports/sysdeps/arm/dl-tlsdesc.S
@@ -50,18 +50,9 @@ _dl_tlsdesc_return:
 	.fnstart
 	.align 2
 _dl_tlsdesc_undefweak:
-	@ Are we allowed a misaligned stack pointer calling read_tp?
-	.save	{lr}
-	stmdb 	sp!, {lr}
-	cfi_adjust_cfa_offset (4)
-	cfi_rel_offset (lr,0)
-	bl 	__aeabi_read_tp
+	GET_TLS (r1)
 	rsb 	r0, r0, #0
-	ldmia 	sp!, {lr}
-	cfi_adjust_cfa_offset (-4)
-	cfi_restore (lr)
 	BX	(lr)
-
 	cfi_endproc
 	.fnend
 	.size	_dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
@@ -106,7 +97,7 @@ _dl_tlsdesc_dynamic:
 	cfi_rel_offset (r4,8)
 	cfi_rel_offset (lr,12)
 	ldr	r1, [r0] /* td */
-	bl	__aeabi_read_tp
+	GET_TLS (lr)
 	mov	r4, r0 /* r4 = tp */
 	ldr	r0, [r0]
 	ldr	r2, [r1, #8] /* gen_count */
diff --git a/ports/sysdeps/arm/sysdep.h b/ports/sysdeps/arm/sysdep.h
index 9230131c78..c525d5b977 100644
--- a/ports/sysdeps/arm/sysdep.h
+++ b/ports/sysdeps/arm/sysdep.h
@@ -150,6 +150,25 @@
 #  define NEGOFF_OFF1(R, OFF)		[R, $OFF]
 #  define NEGOFF_OFF2(R, OFFA, OFFB)	[R, $OFFA]
 # endif
+
+/* Helper to get the TLS base pointer.  The interface is that TMP is a
+   register that may be used to hold the LR, if necessary.  TMP may be
+   LR itself to indicate that LR need not be saved.  The base pointer
+   is returned in R0.  Only R0 and TMP are modified.
+
+   At this generic level we have no tricks to pull.  Call the ABI routine.  */
+# define GET_TLS(TMP)					\
+	push	{ r1, r2, r3, lr };			\
+	cfi_remember_state;				\
+	cfi_adjust_cfa_offset (16);			\
+	cfi_rel_offset (r1, 0);				\
+	cfi_rel_offset (r2, 4);				\
+	cfi_rel_offset (r3, 8);				\
+	cfi_rel_offset (lr, 12);			\
+	bl	__aeabi_read_tp;			\
+	pop	{ r1, r2, r3, lr };			\
+	cfi_restore_state
+
 #endif	/* __ASSEMBLER__ */
 
 /* This number is the offset from the pc at the current location.  */
diff --git a/ports/sysdeps/unix/arm/sysdep.S b/ports/sysdeps/unix/arm/sysdep.S
index d44ee4869a..d82ad258a0 100644
--- a/ports/sysdeps/unix/arm/sysdep.S
+++ b/ports/sysdeps/unix/arm/sysdep.S
@@ -37,14 +37,8 @@ __syscall_error:
 #endif
 
 #ifndef IS_IN_rtld
-	mov ip, lr
-	cfi_register (lr, ip)
-	mov r1, r0
-
-	mov r0, #0xffff0fff
-	mov lr, pc
-	sub pc, r0, #31
-
+	mov	r1, r0
+	GET_TLS (r2)
 	ldr	r2, 1f
 #ifdef __thumb__
 2:	add	r2, r2, pc
@@ -54,7 +48,7 @@ __syscall_error:
 #endif
 	str	r1, [r0, r2]
 	mvn	r0, #0
-	DO_RET(ip)
+	DO_RET(lr)
 
 1:	.word errno(gottpoff) + (. - 2b - PC_OFS)
 #elif RTLD_PRIVATE_ERRNO
diff --git a/ports/sysdeps/unix/sysv/linux/arm/aeabi_read_tp.S b/ports/sysdeps/unix/sysv/linux/arm/aeabi_read_tp.S
index c4ddbc69ff..ecdc3228a3 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/aeabi_read_tp.S
+++ b/ports/sysdeps/unix/sysv/linux/arm/aeabi_read_tp.S
@@ -41,6 +41,12 @@
 
 	.hidden __aeabi_read_tp
 ENTRY (__aeabi_read_tp)
+#ifdef __thumb2__
+	movw	r0, #0x0fe0
+	movt	r0, #0xffff
+	bx	r0
+#else
 	mov	r0, #0xffff0fff
 	sub	pc, r0, #31
+#endif
 END (__aeabi_read_tp)
diff --git a/ports/sysdeps/unix/sysv/linux/arm/clone.S b/ports/sysdeps/unix/sysv/linux/arm/clone.S
index 653bd74102..9009393f33 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/clone.S
+++ b/ports/sysdeps/unix/sysv/linux/arm/clone.S
@@ -74,9 +74,7 @@ PSEUDO_END (__clone)
 #ifdef RESET_PID
 	tst	ip, #CLONE_THREAD
 	bne	3f
-	mov	r0, #0xffff0fff
-	mov	lr, pc
-	sub	pc, r0, #31
+	GET_TLS (lr)
 	mov	r1, r0
 	tst	ip, #CLONE_VM
 	ldr	r7, =SYS_ify(getpid)
diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S b/ports/sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S
index f79bb66f2b..ca50457070 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S
+++ b/ports/sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S
@@ -19,15 +19,7 @@
 
 /* Save the PID value.  */
 #define SAVE_PID \
-	str	lr, [sp, #-4]!;		/* Save LR.  */			\
-	cfi_adjust_cfa_offset (4);					\
-	cfi_rel_offset (lr, 0);						\
-	mov	r0, #0xffff0fff;	/* Point to the high page.  */	\
-	mov	lr, pc;			/* Save our return address.  */	\
-	sub	pc, r0, #31;		/* Jump to the TLS entry.  */	\
-	ldr	lr, [sp], #4;		/* Restore LR.  */		\
-	cfi_adjust_cfa_offset (-4);					\
-	cfi_restore (lr);						\
+	GET_TLS (r2);							\
 	NEGOFF_ADJ_BASE2 (r2, r0, PID_OFFSET); /* Save the TLS addr in r2. */ \
 	ldr	r3, NEGOFF_OFF1 (r2, PID_OFFSET); /* Load the saved PID.  */  \
 	rsb	r0, r3, #0;		/* Negate it.  */		     \
diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h b/ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h
index 9157d03270..2fc053523f 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h
+++ b/ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h
@@ -216,7 +216,7 @@ extern int __local_multiple_threads attribute_hidden;
 	stmfd	sp!, {r0, lr};						\
 	cfi_adjust_cfa_offset (8);					\
 	cfi_rel_offset (lr, 4);						\
-	bl	__aeabi_read_tp;					\
+	GET_TLS (lr);							\
 	NEGOFF_ADJ_BASE (r0, MULTIPLE_THREADS_OFFSET);			\
 	ldr	ip, NEGOFF_OFF1 (r0, MULTIPLE_THREADS_OFFSET);		\
 	ldmfd	sp!, {r0, lr};						\
diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/vfork.S b/ports/sysdeps/unix/sysv/linux/arm/nptl/vfork.S
index 1c6f3bb2bf..216fb2d2eb 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/nptl/vfork.S
+++ b/ports/sysdeps/unix/sysv/linux/arm/nptl/vfork.S
@@ -19,15 +19,7 @@
 
 /* Save the PID value.  */
 #define SAVE_PID \
-	str	lr, [sp, #-4]!;		/* Save LR.  */			\
-	cfi_adjust_cfa_offset (4);					\
-	cfi_rel_offset (lr, 0);						\
-	mov	r0, #0xffff0fff;	/* Point to the high page.  */	\
-	mov	lr, pc;			/* Save our return address.  */	\
-	sub	pc, r0, #31;		/* Jump to the TLS entry.  */	\
-	ldr	lr, [sp], #4;		/* Restore LR.  */		\
-	cfi_adjust_cfa_offset (-4);					\
-	cfi_restore (lr);						\
+	GET_TLS (r2);							\
 	NEGOFF_ADJ_BASE2 (r2, r0, PID_OFFSET); /* Save the TLS addr in r2.  */ \
 	ldr	r3, NEGOFF_OFF1 (r2, PID_OFFSET); /* Load the saved PID.  */   \
 	rsbs	r0, r3, #0;		/* Negate it.  */		      \
diff --git a/ports/sysdeps/unix/sysv/linux/arm/sysdep.h b/ports/sysdeps/unix/sysv/linux/arm/sysdep.h
index 89208a9f19..dc2058b275 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/sysdep.h
+++ b/ports/sysdeps/unix/sysv/linux/arm/sysdep.h
@@ -45,6 +45,36 @@
 
 #ifdef __ASSEMBLER__
 
+/* Internal macro calling the linux kernel kuser_get_tls helper.
+   Note that in thumb mode, a constant pool break is often out of range, so
+   we always expand the constant inline.  */
+#ifdef __thumb2__
+# define GET_TLS_BODY			\
+	movw	r0, #0x0fe0;		\
+	movt	r0, #0xffff;		\
+	blx	r0
+#else
+# define GET_TLS_BODY \
+	mov	r0, #0xffff0fff;	/* Point to the high page.  */	\
+	mov	lr, pc;			/* Save our return address.  */	\
+	sub	pc, r0, #31		/* Jump to the TLS entry.  */
+#endif
+
+/* Helper to get the TLS base pointer.  Save LR in TMP, return in R0,
+   and no other registers clobbered.  TMP may be LR itself to indicate
+   that no save is necessary.  */
+#undef GET_TLS
+#define GET_TLS(TMP)			\
+  .ifnc TMP, lr;			\
+	mov	TMP, lr;		\
+	cfi_register (lr, TMP);		\
+	GET_TLS_BODY;			\
+	mov	lr, TMP;		\
+	cfi_restore (lr);		\
+  .else;				\
+	GET_TLS_BODY;			\
+  .endif
+
 /* Linux uses a negative return value to indicate syscall errors,
    unlike most Unices, which use the condition codes' carry flag.