Leave out gp initialization from kernel entry on mips64

On OpenBSD/mips64, the kernel is compiled with -mno-abicalls. This
disables gp-relative addressing and essentially makes gp a spare
register in the kernel. Hence it is unnecessary to initialize gp when
entering the kernel. The _gp symbol is not needed either.

Suggested by miod@

9 files changed, 8 insertions, 24 deletions

diff --git a/sys/arch/loongson/conf/ld.script b/sys/arch/loongson/conf/ld.script
index c8680b0fc6c..d529e3df319 100644
--- a/sys/arch/loongson/conf/ld.script
+++ b/sys/arch/loongson/conf/ld.script
@@ -7,7 +7,6 @@ SECTIONS
 	.text :		{ *(.text .text.* .gnu.linkonce.t.*) }
 	PROVIDE (etext = .);
 	.rodata :	{ *(.rodata .rodata.* .gnu.linkonce.r.*) }
-	_gp = ALIGN(16) + 0x7ff0;
 	.data :		{ *(.data .data.* .gnu.linkonce.d.*) }
 	.openbsd.randomdata :
 	{
diff --git a/sys/arch/loongson/loongson/locore.S b/sys/arch/loongson/loongson/locore.S
index 481235ec782..fe50aa52cbb 100644
--- a/sys/arch/loongson/loongson/locore.S
+++ b/sys/arch/loongson/loongson/locore.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.S,v 1.8 2017/06/08 11:44:00 visa Exp $ */
+/*	$OpenBSD: locore.S,v 1.9 2021/02/11 14:44:13 visa Exp $ */
 
 /*
  * Copyright (c) 2001-2004 Opsycon AB  (www.opsycon.se / www.opsycon.com)
@@ -53,7 +53,6 @@ locore_start:
 	 * Initialize stack and call machine startup.
 	 */
 	LA	t0, start - FRAMESZ(CF_SZ)
-	LA	gp, _gp
 	PTR_S	ra, CF_RA_OFFS(t0)		# save pmon return address
 	PTR_S	sp, 0(t0)			# and stack
 	move	sp, t0
@@ -111,7 +110,7 @@ LEAF(hw_cpu_spinup_trampoline, 0)
 	LA	t0, cpu_spinup_sp
 	ld	sp, 0(t0)
 	jal	hw_cpu_hatch
-	 LA	gp, _gp
+	nop
 END(hw_cpu_spinup_trampoline)
 
 LEAF(hw_getcurcpu, 0)
diff --git a/sys/arch/mips64/mips64/exception.S b/sys/arch/mips64/mips64/exception.S
index 5d67f094ec4..e4067189fbe 100644
--- a/sys/arch/mips64/mips64/exception.S
+++ b/sys/arch/mips64/mips64/exception.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: exception.S,v 1.40 2019/05/06 12:54:51 visa Exp $ */
+/*	$OpenBSD: exception.S,v 1.41 2021/02/11 14:44:13 visa Exp $ */
 
 /*
  * Copyright (c) 2002-2003 Opsycon AB  (www.opsycon.se / www.opsycon.com)
@@ -205,7 +205,6 @@ NNON_LEAF(k_intr, FRAMESZ(KERN_EXC_FRAME_SIZE), ra)
 #endif
 	.set	at
 	move	sp, k0			# Already on kernel stack
-	LA	gp, _gp
 	and	t0, a1, ~(SR_COP_1_BIT | SR_EXL | SR_INT_ENAB | SR_KSU_MASK)
 	MTC0	t0, COP_0_STATUS_REG
 	MTC0_SR_IE_HAZARD
@@ -242,7 +241,6 @@ NNON_LEAF(u_intr, FRAMESZ(CF_SZ), ra)
 	SAVE_REG(v1, IC, k0, 0)
 #endif
 	PTR_ADDU sp, k0, USPACE-FRAMESZ(CF_SZ)
-	LA	gp, _gp
 	.set	at
 	and	t0, a1, ~(SR_COP_1_BIT | SR_EXL | SR_INT_ENAB | SR_KSU_MASK)
 	MTC0	t0, COP_0_STATUS_REG
@@ -328,7 +326,6 @@ NNON_LEAF(k_general, FRAMESZ(KERN_EXC_FRAME_SIZE), ra)
 #endif
 	.set	at
 	move	sp, k0			# Already on kernel stack
-	LA	gp, _gp
 	and	t0, a1, ~(SR_COP_1_BIT | SR_EXL | SR_INT_ENAB | SR_KSU_MASK)
 	MTC0	t0, COP_0_STATUS_REG
 	MTC0_SR_IE_HAZARD
@@ -370,7 +367,6 @@ NNON_LEAF(u_general, FRAMESZ(CF_SZ), ra)
 #endif
 	SAVE_CPU_SREG(k0, 0)
 	PTR_ADDU sp, k0, USPACE-FRAMESZ(CF_SZ)
-	LA	gp, _gp
 	.set	at
 	and	t0, a1, ~(SR_COP_1_BIT | SR_EXL | SR_INT_ENAB | SR_KSU_MASK)
 	MTC0	t0, COP_0_STATUS_REG
diff --git a/sys/arch/mips64/mips64/exception_tfp.S b/sys/arch/mips64/mips64/exception_tfp.S
index e1ca77e2346..6fdf3686b4d 100644
--- a/sys/arch/mips64/mips64/exception_tfp.S
+++ b/sys/arch/mips64/mips64/exception_tfp.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: exception_tfp.S,v 1.7 2018/05/09 15:03:04 visa Exp $	*/
+/*	$OpenBSD: exception_tfp.S,v 1.8 2021/02/11 14:44:13 visa Exp $	*/
 
 /*
  * Copyright (c) 2012 Miodrag Vallat.
@@ -288,7 +288,6 @@ u_intr:
 	SAVE_CPU(k0, 0)
 	SAVE_CPU_SREG(k0, 0)
 	PTR_ADDU sp, k0, USPACE-FRAMESZ(CF_SZ)
-	LA	gp, _gp
 	.set	at
 	and	t0, a1, ~(SR_COP_1_BIT | SR_EXL | SR_INT_ENAB | SR_KSU_MASK)
 	DMTC0	t0, COP_0_STATUS_REG
@@ -400,7 +399,6 @@ k_intr:
 #endif
 	.set	at
 	move	sp, k0			# Already on kernel stack
-	LA	gp, _gp
 	and	t0, a1, ~(SR_COP_1_BIT | SR_EXL | SR_INT_ENAB | SR_KSU_MASK)
 	DMTC0	t0, COP_0_STATUS_REG
 	MTC0_SR_IE_HAZARD
diff --git a/sys/arch/octeon/conf/ld.script b/sys/arch/octeon/conf/ld.script
index 9fe8c665b08..c5613cc31b3 100644
--- a/sys/arch/octeon/conf/ld.script
+++ b/sys/arch/octeon/conf/ld.script
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ld.script,v 1.6 2021/02/06 09:31:47 visa Exp $	*/
+/*	$OpenBSD: ld.script,v 1.7 2021/02/11 14:44:13 visa Exp $	*/
 
 OUTPUT_FORMAT("elf64-tradbigmips")
 OUTPUT_ARCH(mips)
@@ -40,7 +40,6 @@ SECTIONS
 	. = ALIGN(8);
 	PROVIDE (__kernel_randomdata_end = .);
 
-	_gp = ALIGN(16) + 0x7ff0;
 	.data :
 	{
 		*(.data .data.* .gnu.linkonce.d.*)
diff --git a/sys/arch/octeon/octeon/locore.S b/sys/arch/octeon/octeon/locore.S
index 609d476fd6b..ff2c794e9ef 100644
--- a/sys/arch/octeon/octeon/locore.S
+++ b/sys/arch/octeon/octeon/locore.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.S,v 1.21 2020/07/11 15:18:08 visa Exp $ */
+/*	$OpenBSD: locore.S,v 1.22 2021/02/11 14:44:14 visa Exp $ */
 
 /*
  * Copyright (c) 2001-2004 Opsycon AB  (www.opsycon.se / www.opsycon.com)
@@ -72,8 +72,6 @@ locore_start:
 
 	mtc0	zero, COP_0_CAUSE_REG	# Clear soft interrupts
 
-	LA	gp, _gp
-
 	/* Let the init core continue. The others have to wait. */
 	bne	a2, zero, 2f
 	nop
diff --git a/sys/arch/sgi/conf/ld.script b/sys/arch/sgi/conf/ld.script
index ac05ba0956f..99134c0ea6e 100644
--- a/sys/arch/sgi/conf/ld.script
+++ b/sys/arch/sgi/conf/ld.script
@@ -7,7 +7,6 @@ SECTIONS
 	.text :		{ *(.text .text.* .gnu.linkonce.t.*) }
 	PROVIDE (etext = .);
 	.rodata :	{ *(.rodata .rodata.* .gnu.linkonce.r.*) }
-	_gp = ALIGN(16) + 0x7ff0;
 	.data :		{ *(.data .data.* .gnu.linkonce.d.*) }
 	.openbsd.randomdata :
 	{
diff --git a/sys/arch/sgi/sgi/ip30_nmi.S b/sys/arch/sgi/sgi/ip30_nmi.S
index 1402c986a13..f13c50f2b3a 100644
--- a/sys/arch/sgi/sgi/ip30_nmi.S
+++ b/sys/arch/sgi/sgi/ip30_nmi.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip30_nmi.S,v 1.6 2012/10/03 11:18:23 miod Exp $	*/
+/*	$OpenBSD: ip30_nmi.S,v 1.7 2021/02/11 14:44:14 visa Exp $	*/
 
 /*
  * Copyright (c) 2010 Miodrag Vallat.
@@ -71,7 +71,6 @@ ip30_nmi:
 	.set	at
 
 	PTR_ADDU sp, k0, 0x2000
-	LA	gp, _gp
 	
 	/*
 	 * Interrupts should be disabled. Just in case they aren't,
diff --git a/sys/arch/sgi/sgi/locore.S b/sys/arch/sgi/sgi/locore.S
index 10703adb4a0..39e076bc880 100644
--- a/sys/arch/sgi/sgi/locore.S
+++ b/sys/arch/sgi/sgi/locore.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.S,v 1.19 2019/06/30 07:37:47 visa Exp $ */
+/*	$OpenBSD: locore.S,v 1.20 2021/02/11 14:44:14 visa Exp $ */
 
 /*
  * Copyright (c) 2001-2004 Opsycon AB  (www.opsycon.se / www.opsycon.com)
@@ -55,7 +55,6 @@ locore_start:
 	 * Initialize stack and call machine startup.
 	 */
 	LA	sp, start - FRAMESZ(CF_SZ)
-	LA	gp, _gp
 	jal	mips_init			# mips_init(argc, argv, envp)
 	PTR_S	zero, CF_RA_OFFS(sp)		# Zero out old ra for debugger
 
@@ -73,7 +72,6 @@ LEAF(hw_cpu_spinup_trampoline, 0)
 	ori	v0, SR_KX | SR_UX
 	MTC0	v0, COP_0_STATUS_REG		# disable all interrupts
 	MTC0	zero, COP_0_CAUSE_REG		# Clear soft interrupts
-	LA	gp, _gp
 	jal	hw_cpu_hatch
 	 NOP
 END(hw_cpu_spinup_trampoline)
@@ -122,7 +120,6 @@ LEAF(ip27_cpu_spinup_trampoline, 0)
 	and	v0, v1
 	MTC0	v0, COP_0_STATUS_REG		# Disable all interrupts.
 	MTC0	zero, COP_0_CAUSE_REG		# Clear soft interrupts.
-	LA	gp, _gp
 
 	/* Wait the turn of this CPU. */
 	LA	v1, ip27_spinup_turn