[PATCH 0/4] Use scratch registers on XLR/XLS/XLP

[PATCH 0/4] Use scratch registers on XLR/XLS/XLP

[Jayachandran C]

This set of patches enable the use of scratch registers on XLR/XLS and XLP
(cop0 reg 22, sel 0-7) to optimize the generated TLB handlers.

The current code assumes scratch is 31, which is fixed by the first patch.
The second patch fixes a minor issue in checking if scratch is allocated.
The third patch enables use of a scratch register when it is available
even on a 32-bit or non-r2 platform. The fourth patch is a cleanup to 
consolidate all the defines needed into one file, this patch does not
have any change in logic.

In the earlier scheme, if MIPS_PGD_C0_CONTEXT was defined, the Context
register or a scratch register would contain the current PGD, and the
Xcontext would contain the smp_processor_id shifted to index pointers.

In the new scheme, the behavior when MIPS_PGD_C0_CONTEXT is defined
remains the same.  But when it is not defined, we still try to allocate
a scratch register for the current pgd and the smp processor id remains
in Context.

There is also an additional change is to generate the
tlbmiss_handler_setup_pgd() function even when MIPS_PGD_C0_CONTEXT is not
defined.  This function will save the PGD in pgd_current[] and also in
the scratch register if one has been allocated.

Comments/testing welcome.

Thanks,
JC.

Changes in v3:
* Add patch 2 - fix up  check for a valid scratch register

Changes in v2:
* Update macros in thread-info.h, remove __ASSEMBLY__ part
* add ASM_CPUID_MFC0 and UASM_i_CPUID_MFC0 which allows us to remove
  a lot of conditional compilation.
* make c0_kscratch a inline function and remove global variable

Jayachandran C (4):
  MIPS: Allow platform specific scratch registers
  MIPS: Fixup check for invalid scratch register
  MIPS: mm: Use scratch for PGD when !CONFIG_MIPS_PGD_C0_CONTEXT
  MIPS: Move definition of SMP processor id register to header file

 arch/mips/include/asm/mmu_context.h |   22 ++---
 arch/mips/include/asm/stackframe.h  |   24 ++---
 arch/mips/include/asm/thread_info.h |   30 +++++-
 arch/mips/kernel/cpu-probe.c        |    1 +
 arch/mips/mm/tlbex.c                |  186 +++++++++++++++++------------------
 5 files changed, 132 insertions(+), 131 deletions(-)

-- 
1.7.9.5

[PATCH 1/4] MIPS: Allow platform specific scratch registers

[Jayachandran C]

XLR/XLP COP0 scratch is register 22, sel 0-7. Add a function
c0_kscratch() which returns the scratch register for the platform,
and use the return value while generating TLB handlers.

Setup kscratch_mask to 0xf for XLR/XLP since the config4 register
does not exist. This allows the kernel to allocate scratch registers
0-3 if needed.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---
 arch/mips/kernel/cpu-probe.c |    1 +
 arch/mips/mm/tlbex.c         |   41 ++++++++++++++++++++++++++---------------
 2 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index c6568bf..265c97d 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -959,6 +959,7 @@ static inline void cpu_probe_netlogic(struct cpuinfo_mips *c, int cpu)
 		set_isa(c, MIPS_CPU_ISA_M64R1);
 		c->tlbsize = ((read_c0_config1() >> 25) & 0x3f) + 1;
 	}
+	c->kscratch_mask = 0xf;
 }
 
 #ifdef CONFIG_64BIT
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index ce9818e..b2eaa1c 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -309,6 +309,17 @@ static int check_for_high_segbits __cpuinitdata;
 
 static unsigned int kscratch_used_mask __cpuinitdata;
 
+static inline int __maybe_unused c0_kscratch(void)
+{
+	switch (current_cpu_type()) {
+	case CPU_XLP:
+	case CPU_XLR:
+		return 22;
+	default:
+		return 31;
+	}
+}
+
 static int __cpuinit allocate_kscratch(void)
 {
 	int r;
@@ -340,7 +351,7 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 
 	if (scratch_reg > 0) {
 		/* Save in CPU local C0_KScratch? */
-		UASM_i_MTC0(p, 1, 31, scratch_reg);
+		UASM_i_MTC0(p, 1, c0_kscratch(), scratch_reg);
 		r.r1 = K0;
 		r.r2 = K1;
 		r.r3 = 1;
@@ -389,7 +400,7 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 static void __cpuinit build_restore_work_registers(u32 **p)
 {
 	if (scratch_reg > 0) {
-		UASM_i_MFC0(p, 1, 31, scratch_reg);
+		UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 		return;
 	}
 	/* K0 already points to save area, restore $1 and $2  */
@@ -678,7 +689,7 @@ static __cpuinit void build_restore_pagemask(u32 **p,
 			uasm_il_b(p, r, lid);
 		}
 		if (scratch_reg > 0)
-			UASM_i_MFC0(p, 1, 31, scratch_reg);
+			UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 		else
 			UASM_i_LW(p, 1, scratchpad_offset(0), 0);
 	} else {
@@ -821,7 +832,7 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 #ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 	if (pgd_reg != -1) {
 		/* pgd is in pgd_reg */
-		UASM_i_MFC0(p, ptr, 31, pgd_reg);
+		UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
 	} else {
 		/*
 		 * &pgd << 11 stored in CONTEXT [23..63].
@@ -934,7 +945,7 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 
 		if (mode == refill_scratch) {
 			if (scratch_reg > 0)
-				UASM_i_MFC0(p, 1, 31, scratch_reg);
+				UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 			else
 				UASM_i_LW(p, 1, scratchpad_offset(0), 0);
 		} else {
@@ -1100,7 +1111,7 @@ struct mips_huge_tlb_info {
 static struct mips_huge_tlb_info __cpuinit
 build_fast_tlb_refill_handler (u32 **p, struct uasm_label **l,
 			       struct uasm_reloc **r, unsigned int tmp,
-			       unsigned int ptr, int c0_scratch)
+			       unsigned int ptr, int c0_scratch_reg)
 {
 	struct mips_huge_tlb_info rv;
 	unsigned int even, odd;
@@ -1114,12 +1125,12 @@ build_fast_tlb_refill_handler (u32 **p, struct uasm_label **l,
 		UASM_i_MFC0(p, tmp, C0_BADVADDR);
 
 		if (pgd_reg != -1)
-			UASM_i_MFC0(p, ptr, 31, pgd_reg);
+			UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
 		else
 			UASM_i_MFC0(p, ptr, C0_CONTEXT);
 
-		if (c0_scratch >= 0)
-			UASM_i_MTC0(p, scratch, 31, c0_scratch);
+		if (c0_scratch_reg >= 0)
+			UASM_i_MTC0(p, scratch, c0_kscratch(), c0_scratch_reg);
 		else
 			UASM_i_SW(p, scratch, scratchpad_offset(0), 0);
 
@@ -1134,14 +1145,14 @@ build_fast_tlb_refill_handler (u32 **p, struct uasm_label **l,
 		}
 	} else {
 		if (pgd_reg != -1)
-			UASM_i_MFC0(p, ptr, 31, pgd_reg);
+			UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
 		else
 			UASM_i_MFC0(p, ptr, C0_CONTEXT);
 
 		UASM_i_MFC0(p, tmp, C0_BADVADDR);
 
-		if (c0_scratch >= 0)
-			UASM_i_MTC0(p, scratch, 31, c0_scratch);
+		if (c0_scratch_reg >= 0)
+			UASM_i_MTC0(p, scratch, c0_kscratch(), c0_scratch_reg);
 		else
 			UASM_i_SW(p, scratch, scratchpad_offset(0), 0);
 
@@ -1246,8 +1257,8 @@ build_fast_tlb_refill_handler (u32 **p, struct uasm_label **l,
 	}
 	UASM_i_MTC0(p, odd, C0_ENTRYLO1); /* load it */
 
-	if (c0_scratch >= 0) {
-		UASM_i_MFC0(p, scratch, 31, c0_scratch);
+	if (c0_scratch_reg >= 0) {
+		UASM_i_MFC0(p, scratch, c0_kscratch(), c0_scratch_reg);
 		build_tlb_write_entry(p, l, r, tlb_random);
 		uasm_l_leave(l, *p);
 		rv.restore_scratch = 1;
@@ -1494,7 +1505,7 @@ static void __cpuinit build_r4000_setup_pgd(void)
 	} else {
 		/* PGD in c0_KScratch */
 		uasm_i_jr(&p, 31);
-		UASM_i_MTC0(&p, a0, 31, pgd_reg);
+		UASM_i_MTC0(&p, a0, c0_kscratch(), pgd_reg);
 	}
 	if (p - tlbmiss_handler_setup_pgd_array > ARRAY_SIZE(tlbmiss_handler_setup_pgd_array))
 		panic("tlbmiss_handler_setup_pgd_array space exceeded");
-- 
1.7.9.5

[PATCH 2/4] MIPS: Fixup check for invalid scratch register

[Jayachandran C]

The invalid value for scratch register is -1, so update the checks of
the form (scratch_reg > 0) to be (scratch_reg >= 0).  This will fix
the case in Netlogic XLP where the scratch_reg can be 0.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---
 arch/mips/mm/tlbex.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index b2eaa1c..4a6817c 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -349,7 +349,7 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 	int smp_processor_id_sel;
 	int smp_processor_id_shift;
 
-	if (scratch_reg > 0) {
+	if (scratch_reg >= 0) {
 		/* Save in CPU local C0_KScratch? */
 		UASM_i_MTC0(p, 1, c0_kscratch(), scratch_reg);
 		r.r1 = K0;
@@ -399,7 +399,7 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 
 static void __cpuinit build_restore_work_registers(u32 **p)
 {
-	if (scratch_reg > 0) {
+	if (scratch_reg >= 0) {
 		UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 		return;
 	}
@@ -688,7 +688,7 @@ static __cpuinit void build_restore_pagemask(u32 **p,
 			uasm_i_mtc0(p, 0, C0_PAGEMASK);
 			uasm_il_b(p, r, lid);
 		}
-		if (scratch_reg > 0)
+		if (scratch_reg >= 0)
 			UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 		else
 			UASM_i_LW(p, 1, scratchpad_offset(0), 0);
@@ -944,7 +944,7 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		uasm_i_jr(p, ptr);
 
 		if (mode == refill_scratch) {
-			if (scratch_reg > 0)
+			if (scratch_reg >= 0)
 				UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 			else
 				UASM_i_LW(p, 1, scratchpad_offset(0), 0);
@@ -1301,7 +1301,7 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
 	memset(relocs, 0, sizeof(relocs));
 	memset(final_handler, 0, sizeof(final_handler));
 
-	if ((scratch_reg > 0 || scratchpad_available()) && use_bbit_insns()) {
+	if ((scratch_reg >= 0 || scratchpad_available()) && use_bbit_insns()) {
 		htlb_info = build_fast_tlb_refill_handler(&p, &l, &r, K0, K1,
 							  scratch_reg);
 		vmalloc_mode = refill_scratch;
-- 
1.7.9.5

[PATCH 3/4] MIPS: mm: Use scratch for PGD when !CONFIG_MIPS_PGD_C0_CONTEXT

[Jayachandran C]

Allow usage of scratch register for current pgd even when
MIPS_PGD_C0_CONTEXT is not configured. MIPS_PGD_C0_CONTEXT is set
for 64r2 platforms to indicate availability of Xcontext for saving
cpuid, thus freeing Context to be used for saving PGD. This option
was also tied to using a scratch register for storing PGD.

This commit will allow usage of scratch register to store the current
pgd if one can be allocated for the platform, even when
MIPS_PGD_C0_CONTEXT is not set. The cpuid will be kept in the CP0
Context register in this case.

The code to store the current pgd for the TLB miss handler is now
generated in all cases. When scratch register is available, the PGD
is also stored in the scratch register.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---
 arch/mips/include/asm/mmu_context.h |    7 +-
 arch/mips/mm/tlbex.c                |  142 ++++++++++++++++++++++-------------
 2 files changed, 92 insertions(+), 57 deletions(-)

diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h
index 8201160..3e20577 100644
--- a/arch/mips/include/asm/mmu_context.h
+++ b/arch/mips/include/asm/mmu_context.h
@@ -24,8 +24,6 @@
 #endif /* SMTC */
 #include <asm-generic/mm_hooks.h>
 
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
-
 #define TLBMISS_HANDLER_SETUP_PGD(pgd)					\
 do {									\
 	void (*tlbmiss_handler_setup_pgd)(unsigned long);		\
@@ -36,6 +34,8 @@ do {									\
 	tlbmiss_handler_setup_pgd((unsigned long)(pgd));		\
 } while (0)
 
+
+#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 #define TLBMISS_HANDLER_SETUP()						\
 	do {								\
 		TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);		\
@@ -51,9 +51,6 @@ do {									\
  */
 extern unsigned long pgd_current[];
 
-#define TLBMISS_HANDLER_SETUP_PGD(pgd) \
-	pgd_current[smp_processor_id()] = (unsigned long)(pgd)
-
 #ifdef CONFIG_32BIT
 #define TLBMISS_HANDLER_SETUP()						\
 	write_c0_context((unsigned long) smp_processor_id() << 25);	\
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 4a6817c..1b372b7 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -829,11 +829,11 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 	}
 	/* No uasm_i_nop needed here, since the next insn doesn't touch TMP. */
 
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 	if (pgd_reg != -1) {
 		/* pgd is in pgd_reg */
 		UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
 	} else {
+#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 		/*
 		 * &pgd << 11 stored in CONTEXT [23..63].
 		 */
@@ -845,30 +845,30 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		/* 1 0	1 0 1  << 6  xkphys cached */
 		uasm_i_ori(p, ptr, ptr, 0x540);
 		uasm_i_drotr(p, ptr, ptr, 11);
-	}
 #elif defined(CONFIG_SMP)
-# ifdef	 CONFIG_MIPS_MT_SMTC
-	/*
-	 * SMTC uses TCBind value as "CPU" index
-	 */
-	uasm_i_mfc0(p, ptr, C0_TCBIND);
-	uasm_i_dsrl_safe(p, ptr, ptr, 19);
+# ifdef CONFIG_MIPS_MT_SMTC
+		/*
+		 * SMTC uses TCBind value as "CPU" index
+		 */
+		uasm_i_mfc0(p, ptr, C0_TCBIND);
+		uasm_i_dsrl_safe(p, ptr, ptr, 19);
 # else
-	/*
-	 * 64 bit SMP running in XKPHYS has smp_processor_id() << 3
-	 * stored in CONTEXT.
-	 */
-	uasm_i_dmfc0(p, ptr, C0_CONTEXT);
-	uasm_i_dsrl_safe(p, ptr, ptr, 23);
+		/*
+		 * 64 bit SMP running in XKPHYS has smp_processor_id() << 3
+		 * stored in CONTEXT.
+		 */
+		uasm_i_dmfc0(p, ptr, C0_CONTEXT);
+		uasm_i_dsrl_safe(p, ptr, ptr, 23);
 # endif
-	UASM_i_LA_mostly(p, tmp, pgdc);
-	uasm_i_daddu(p, ptr, ptr, tmp);
-	uasm_i_dmfc0(p, tmp, C0_BADVADDR);
-	uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
+		UASM_i_LA_mostly(p, tmp, pgdc);
+		uasm_i_daddu(p, ptr, ptr, tmp);
+		uasm_i_dmfc0(p, tmp, C0_BADVADDR);
+		uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
 #else
-	UASM_i_LA_mostly(p, ptr, pgdc);
-	uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
+		UASM_i_LA_mostly(p, ptr, pgdc);
+		uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
 #endif
+	}
 
 	uasm_l_vmalloc_done(l, *p);
 
@@ -963,31 +963,37 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 static void __cpuinit __maybe_unused
 build_get_pgde32(u32 **p, unsigned int tmp, unsigned int ptr)
 {
-	long pgdc = (long)pgd_current;
+	if (pgd_reg != -1) {
+		/* pgd is in pgd_reg */
+		uasm_i_mfc0(p, ptr, c0_kscratch(), pgd_reg);
+		uasm_i_mfc0(p, tmp, C0_BADVADDR); /* get faulting address */
+	} else {
+		long pgdc = (long)pgd_current;
 
-	/* 32 bit SMP has smp_processor_id() stored in CONTEXT. */
+		/* 32 bit SMP has smp_processor_id() stored in CONTEXT. */
 #ifdef CONFIG_SMP
-#ifdef	CONFIG_MIPS_MT_SMTC
-	/*
-	 * SMTC uses TCBind value as "CPU" index
-	 */
-	uasm_i_mfc0(p, ptr, C0_TCBIND);
-	UASM_i_LA_mostly(p, tmp, pgdc);
-	uasm_i_srl(p, ptr, ptr, 19);
-#else
-	/*
-	 * smp_processor_id() << 3 is stored in CONTEXT.
-	 */
-	uasm_i_mfc0(p, ptr, C0_CONTEXT);
-	UASM_i_LA_mostly(p, tmp, pgdc);
-	uasm_i_srl(p, ptr, ptr, 23);
-#endif
-	uasm_i_addu(p, ptr, tmp, ptr);
+# ifdef CONFIG_MIPS_MT_SMTC
+		/*
+		 * SMTC uses TCBind value as "CPU" index
+		 */
+		uasm_i_mfc0(p, ptr, C0_TCBIND);
+		UASM_i_LA_mostly(p, tmp, pgdc);
+		uasm_i_srl(p, ptr, ptr, 19);
+# else
+		/*
+		 * smp_processor_id() << 3 is stored in CONTEXT.
+		 */
+		uasm_i_mfc0(p, ptr, C0_CONTEXT);
+		UASM_i_LA_mostly(p, tmp, pgdc);
+		uasm_i_srl(p, ptr, ptr, 23);
+# endif
+		uasm_i_addu(p, ptr, tmp, ptr);
 #else
-	UASM_i_LA_mostly(p, ptr, pgdc);
+		UASM_i_LA_mostly(p, ptr, pgdc);
 #endif
-	uasm_i_mfc0(p, tmp, C0_BADVADDR); /* get faulting address */
-	uasm_i_lw(p, ptr, uasm_rel_lo(pgdc), ptr);
+		uasm_i_mfc0(p, tmp, C0_BADVADDR); /* get faulting address */
+		uasm_i_lw(p, ptr, uasm_rel_lo(pgdc), ptr);
+	}
 	uasm_i_srl(p, tmp, tmp, PGDIR_SHIFT); /* get pgd only bits */
 	uasm_i_sll(p, tmp, tmp, PGD_T_LOG2);
 	uasm_i_addu(p, ptr, ptr, tmp); /* add in pgd offset */
@@ -1468,16 +1474,17 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
 u32 handle_tlbl[FASTPATH_SIZE] __cacheline_aligned;
 u32 handle_tlbs[FASTPATH_SIZE] __cacheline_aligned;
 u32 handle_tlbm[FASTPATH_SIZE] __cacheline_aligned;
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 u32 tlbmiss_handler_setup_pgd_array[16] __cacheline_aligned;
 
-static void __cpuinit build_r4000_setup_pgd(void)
+static void __cpuinit build_setup_pgd(void)
 {
 	const int a0 = 4;
-	const int a1 = 5;
+	const int __maybe_unused a1 = 5;
+	const int __maybe_unused a2 = 6;
 	u32 *p = tlbmiss_handler_setup_pgd_array;
-	struct uasm_label *l = labels;
-	struct uasm_reloc *r = relocs;
+#ifndef CONFIG_MIPS_PGD_C0_CONTEXT
+	long pgdc = (long)pgd_current;
+#endif
 
 	memset(tlbmiss_handler_setup_pgd_array, 0, sizeof(tlbmiss_handler_setup_pgd_array));
 	memset(labels, 0, sizeof(labels));
@@ -1485,7 +1492,11 @@ static void __cpuinit build_r4000_setup_pgd(void)
 
 	pgd_reg = allocate_kscratch();
 
+#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 	if (pgd_reg == -1) {
+		struct uasm_label *l = labels;
+		struct uasm_reloc *r = relocs;
+
 		/* PGD << 11 in c0_Context */
 		/*
 		 * If it is a ckseg0 address, convert to a physical
@@ -1507,6 +1518,37 @@ static void __cpuinit build_r4000_setup_pgd(void)
 		uasm_i_jr(&p, 31);
 		UASM_i_MTC0(&p, a0, c0_kscratch(), pgd_reg);
 	}
+#else
+	/* Save PGD to pgd_current[smp_processor_id()] */
+#if defined(CONFIG_SMP)
+# ifdef CONFIG_MIPS_MT_SMTC
+	/*
+	 * SMTC uses TCBind value as "CPU" index
+	 */
+	uasm_i_mfc0(&p, a1, C0_TCBIND);
+	uasm_i_dsrl_safe(&p, a1, a1, 19);
+# else
+	/*
+	 * smp_processor_id() is in CONTEXT
+	 */
+	UASM_i_MFC0(&p, a1, C0_CONTEXT);
+	uasm_i_dsrl_safe(&p, a1, a1, 23);
+# endif
+	UASM_i_LA_mostly(&p, a2, pgdc);
+	UASM_i_ADDU(&p, a2, a2, a1);
+	UASM_i_SW(&p, a0, uasm_rel_lo(pgdc), a2);
+#else
+	UASM_i_LA_mostly(&p, a2, pgdc);
+	UASM_i_SW(&p, a0, uasm_rel_lo(pgdc), a2);
+#endif /* SMP */
+	uasm_i_jr(&p, 31);
+
+	/* if pgd_reg is allocated, save PGD also to scratch register */
+	if (pgd_reg != -1)
+		UASM_i_MTC0(&p, a0, c0_kscratch(), pgd_reg);
+	else
+		uasm_i_nop(&p);
+#endif
 	if (p - tlbmiss_handler_setup_pgd_array > ARRAY_SIZE(tlbmiss_handler_setup_pgd_array))
 		panic("tlbmiss_handler_setup_pgd_array space exceeded");
 	uasm_resolve_relocs(relocs, labels);
@@ -1517,7 +1559,6 @@ static void __cpuinit build_r4000_setup_pgd(void)
 		     tlbmiss_handler_setup_pgd_array,
 		     ARRAY_SIZE(tlbmiss_handler_setup_pgd_array));
 }
-#endif
 
 static void __cpuinit
 iPTE_LW(u32 **p, unsigned int pte, unsigned int ptr)
@@ -2199,6 +2240,7 @@ void __cpuinit build_tlb_refill_handler(void)
 		if (!run_once) {
 			if (!cpu_has_local_ebase)
 				build_r3000_tlb_refill_handler();
+			build_setup_pgd();
 			build_r3000_tlb_load_handler();
 			build_r3000_tlb_store_handler();
 			build_r3000_tlb_modify_handler();
@@ -2221,9 +2263,7 @@ void __cpuinit build_tlb_refill_handler(void)
 	default:
 		if (!run_once) {
 			scratch_reg = allocate_kscratch();
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
-			build_r4000_setup_pgd();
-#endif
+			build_setup_pgd();
 			build_r4000_tlb_load_handler();
 			build_r4000_tlb_store_handler();
 			build_r4000_tlb_modify_handler();
@@ -2244,8 +2284,6 @@ void __cpuinit flush_tlb_handlers(void)
 			   (unsigned long)handle_tlbs + sizeof(handle_tlbs));
 	local_flush_icache_range((unsigned long)handle_tlbm,
 			   (unsigned long)handle_tlbm + sizeof(handle_tlbm));
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 	local_flush_icache_range((unsigned long)tlbmiss_handler_setup_pgd_array,
 			   (unsigned long)tlbmiss_handler_setup_pgd_array + sizeof(handle_tlbm));
-#endif
 }
-- 
1.7.9.5

[PATCH 4/4] MIPS: Move definition of SMP processor id register to header file

[Jayachandran C]

The definition of the CP0 register used to save the smp processor
id is repicated in many files, move them all to thread_info.h.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---
 arch/mips/include/asm/mmu_context.h |   17 +++-----
 arch/mips/include/asm/stackframe.h  |   24 +++--------
 arch/mips/include/asm/thread_info.h |   30 +++++++++++++-
 arch/mips/mm/tlbex.c                |   75 +++++------------------------------
 4 files changed, 50 insertions(+), 96 deletions(-)

diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h
index 3e20577..8b138cf 100644
--- a/arch/mips/include/asm/mmu_context.h
+++ b/arch/mips/include/asm/mmu_context.h
@@ -34,15 +34,15 @@ do {									\
 	tlbmiss_handler_setup_pgd((unsigned long)(pgd));		\
 } while (0)
 
-
 #ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 #define TLBMISS_HANDLER_SETUP()						\
 	do {								\
 		TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);		\
-		write_c0_xcontext((unsigned long) smp_processor_id() << 51); \
+		write_c0_xcontext((unsigned long) smp_processor_id() <<	\
+						SMP_CPUID_REGSHIFT);	\
 	} while (0)
 
-#else /* CONFIG_MIPS_PGD_C0_CONTEXT: using  pgd_current*/
+#else /* !CONFIG_MIPS_PGD_C0_CONTEXT: using  pgd_current*/
 
 /*
  * For the fast tlb miss handlers, we keep a per cpu array of pointers
@@ -51,18 +51,11 @@ do {									\
  */
 extern unsigned long pgd_current[];
 
-#ifdef CONFIG_32BIT
-#define TLBMISS_HANDLER_SETUP()						\
-	write_c0_context((unsigned long) smp_processor_id() << 25);	\
-	back_to_back_c0_hazard();					\
-	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
-#endif
-#ifdef CONFIG_64BIT
 #define TLBMISS_HANDLER_SETUP()						\
-	write_c0_context((unsigned long) smp_processor_id() << 26);	\
+	write_c0_context((unsigned long) smp_processor_id() <<		\
+						SMP_CPUID_REGSHIFT);	\
 	back_to_back_c0_hazard();					\
 	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
-#endif
 #endif /* CONFIG_MIPS_PGD_C0_CONTEXT*/
 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 
diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
index a89d1b1..faefe31 100644
--- a/arch/mips/include/asm/stackframe.h
+++ b/arch/mips/include/asm/stackframe.h
@@ -17,6 +17,7 @@
 #include <asm/asmmacro.h>
 #include <asm/mipsregs.h>
 #include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
 
 /*
  * For SMTC kernel, global IE should be left set, and interrupts
@@ -85,21 +86,8 @@
 		.endm
 
 #ifdef CONFIG_SMP
-#ifdef CONFIG_MIPS_MT_SMTC
-#define PTEBASE_SHIFT	19	/* TCBIND */
-#define CPU_ID_REG CP0_TCBIND
-#define CPU_ID_MFC0 mfc0
-#elif defined(CONFIG_MIPS_PGD_C0_CONTEXT)
-#define PTEBASE_SHIFT	48	/* XCONTEXT */
-#define CPU_ID_REG CP0_XCONTEXT
-#define CPU_ID_MFC0 MFC0
-#else
-#define PTEBASE_SHIFT	23	/* CONTEXT */
-#define CPU_ID_REG CP0_CONTEXT
-#define CPU_ID_MFC0 MFC0
-#endif
 		.macro	get_saved_sp	/* SMP variation */
-		CPU_ID_MFC0	k0, CPU_ID_REG
+		ASM_CPUID_MFC0	k0, $SMP_CPUID_REG
 #if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
 		lui	k1, %hi(kernelsp)
 #else
@@ -109,17 +97,17 @@
 		daddiu	k1, %hi(kernelsp)
 		dsll	k1, 16
 #endif
-		LONG_SRL	k0, PTEBASE_SHIFT
+		LONG_SRL	k0, SMP_CPUID_PTRSHIFT
 		LONG_ADDU	k1, k0
 		LONG_L	k1, %lo(kernelsp)(k1)
 		.endm
 
 		.macro	set_saved_sp stackp temp temp2
-		CPU_ID_MFC0	\temp, CPU_ID_REG
-		LONG_SRL	\temp, PTEBASE_SHIFT
+		ASM_CPUID_MFC0	\temp, $SMP_CPUID_REG
+		LONG_SRL	\temp, SMP_CPUID_PTRSHIFT
 		LONG_S	\stackp, kernelsp(\temp)
 		.endm
-#else
+#else /* !CONFIG_SMP */
 		.macro	get_saved_sp	/* Uniprocessor variation */
 #ifdef CONFIG_CPU_JUMP_WORKAROUNDS
 		/*
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index 61215a3..ddff267 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -147,6 +147,34 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_ALLWORK_MASK	(_TIF_NOHZ | _TIF_WORK_MASK |		\
 				 _TIF_WORK_SYSCALL_EXIT)
 
-#endif /* __KERNEL__ */
+/*
+ * We stash processor id into a COP0 register to retrieve it fast
+ * at kernel exception entry.
+ */
+#if defined(CONFIG_MIPS_MT_SMTC)
+#define SMP_CPUID_REG		2, 2	/* TCBIND */
+#define SMP_CPUID_PTRSHIFT	19
+#elif defined(CONFIG_MIPS_PGD_C0_CONTEXT)
+#define SMP_CPUID_REG		20, 0	/* XCONTEXT */
+#define SMP_CPUID_PTRSHIFT	48
+#else
+#define SMP_CPUID_REG		4, 0	/* CONTEXT */
+#define SMP_CPUID_PTRSHIFT	23
+#endif
 
+#ifdef CONFIG_64BIT
+#define SMP_CPUID_REGSHIFT	(SMP_CPUID_PTRSHIFT + 3)
+#else
+#define SMP_CPUID_REGSHIFT	(SMP_CPUID_PTRSHIFT + 2)
+#endif
+
+#ifdef CONFIG_MIPS_MT_SMTC
+#define ASM_CPUID_MFC0		mfc0
+#define UASM_i_CPUID_MFC0	uasm_i_mfc0
+#else
+#define ASM_CPUID_MFC0		MFC0
+#define UASM_i_CPUID_MFC0	UASM_i_MFC0
+#endif
+
+#endif /* __KERNEL__ */
 #endif /* _ASM_THREAD_INFO_H */
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 1b372b7..8eca735 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -345,10 +345,6 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 {
 	struct work_registers r;
 
-	int smp_processor_id_reg;
-	int smp_processor_id_sel;
-	int smp_processor_id_shift;
-
 	if (scratch_reg >= 0) {
 		/* Save in CPU local C0_KScratch? */
 		UASM_i_MTC0(p, 1, c0_kscratch(), scratch_reg);
@@ -359,25 +355,9 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 	}
 
 	if (num_possible_cpus() > 1) {
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
-		smp_processor_id_shift = 51;
-		smp_processor_id_reg = 20; /* XContext */
-		smp_processor_id_sel = 0;
-#else
-# ifdef CONFIG_32BIT
-		smp_processor_id_shift = 25;
-		smp_processor_id_reg = 4; /* Context */
-		smp_processor_id_sel = 0;
-# endif
-# ifdef CONFIG_64BIT
-		smp_processor_id_shift = 26;
-		smp_processor_id_reg = 4; /* Context */
-		smp_processor_id_sel = 0;
-# endif
-#endif
 		/* Get smp_processor_id */
-		UASM_i_MFC0(p, K0, smp_processor_id_reg, smp_processor_id_sel);
-		UASM_i_SRL_SAFE(p, K0, K0, smp_processor_id_shift);
+		UASM_i_CPUID_MFC0(p, K0, SMP_CPUID_REG);
+		UASM_i_SRL_SAFE(p, K0, K0, SMP_CPUID_REGSHIFT);
 
 		/* handler_reg_save index in K0 */
 		UASM_i_SLL(p, K0, K0, ilog2(sizeof(struct tlb_reg_save)));
@@ -833,7 +813,7 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		/* pgd is in pgd_reg */
 		UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
 	} else {
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
+#if defined(CONFIG_MIPS_PGD_C0_CONTEXT)
 		/*
 		 * &pgd << 11 stored in CONTEXT [23..63].
 		 */
@@ -846,20 +826,8 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		uasm_i_ori(p, ptr, ptr, 0x540);
 		uasm_i_drotr(p, ptr, ptr, 11);
 #elif defined(CONFIG_SMP)
-# ifdef CONFIG_MIPS_MT_SMTC
-		/*
-		 * SMTC uses TCBind value as "CPU" index
-		 */
-		uasm_i_mfc0(p, ptr, C0_TCBIND);
-		uasm_i_dsrl_safe(p, ptr, ptr, 19);
-# else
-		/*
-		 * 64 bit SMP running in XKPHYS has smp_processor_id() << 3
-		 * stored in CONTEXT.
-		 */
-		uasm_i_dmfc0(p, ptr, C0_CONTEXT);
-		uasm_i_dsrl_safe(p, ptr, ptr, 23);
-# endif
+		UASM_i_CPUID_MFC0(p, ptr, SMP_CPUID_REG);
+		uasm_i_dsrl_safe(p, ptr, ptr, SMP_CPUID_PTRSHIFT);
 		UASM_i_LA_mostly(p, tmp, pgdc);
 		uasm_i_daddu(p, ptr, ptr, tmp);
 		uasm_i_dmfc0(p, tmp, C0_BADVADDR);
@@ -972,21 +940,9 @@ build_get_pgde32(u32 **p, unsigned int tmp, unsigned int ptr)
 
 		/* 32 bit SMP has smp_processor_id() stored in CONTEXT. */
 #ifdef CONFIG_SMP
-# ifdef CONFIG_MIPS_MT_SMTC
-		/*
-		 * SMTC uses TCBind value as "CPU" index
-		 */
-		uasm_i_mfc0(p, ptr, C0_TCBIND);
+		uasm_i_mfc0(p, ptr, SMP_CPUID_REG);
 		UASM_i_LA_mostly(p, tmp, pgdc);
-		uasm_i_srl(p, ptr, ptr, 19);
-# else
-		/*
-		 * smp_processor_id() << 3 is stored in CONTEXT.
-		 */
-		uasm_i_mfc0(p, ptr, C0_CONTEXT);
-		UASM_i_LA_mostly(p, tmp, pgdc);
-		uasm_i_srl(p, ptr, ptr, 23);
-# endif
+		uasm_i_srl(p, ptr, ptr, SMP_CPUID_PTRSHIFT);
 		uasm_i_addu(p, ptr, tmp, ptr);
 #else
 		UASM_i_LA_mostly(p, ptr, pgdc);
@@ -1519,21 +1475,10 @@ static void __cpuinit build_setup_pgd(void)
 		UASM_i_MTC0(&p, a0, c0_kscratch(), pgd_reg);
 	}
 #else
+#ifdef CONFIG_SMP
 	/* Save PGD to pgd_current[smp_processor_id()] */
-#if defined(CONFIG_SMP)
-# ifdef CONFIG_MIPS_MT_SMTC
-	/*
-	 * SMTC uses TCBind value as "CPU" index
-	 */
-	uasm_i_mfc0(&p, a1, C0_TCBIND);
-	uasm_i_dsrl_safe(&p, a1, a1, 19);
-# else
-	/*
-	 * smp_processor_id() is in CONTEXT
-	 */
-	UASM_i_MFC0(&p, a1, C0_CONTEXT);
-	uasm_i_dsrl_safe(&p, a1, a1, 23);
-# endif
+	UASM_i_CPUID_MFC0(&p, a1, SMP_CPUID_REG);
+	uasm_i_dsrl_safe(&p, a1, a1, SMP_CPUID_PTRSHIFT);
 	UASM_i_LA_mostly(&p, a2, pgdc);
 	UASM_i_ADDU(&p, a2, a2, a1);
 	UASM_i_SW(&p, a0, uasm_rel_lo(pgdc), a2);
-- 
1.7.9.5

[PATCH UPDATED 3/4] MIPS: mm: Use scratch for PGD when !CONFIG_MIPS_PGD_C0_CONTEXT

[Jayachandran C]

Allow usage of scratch register for current pgd even when
MIPS_PGD_C0_CONTEXT is not configured. MIPS_PGD_C0_CONTEXT is set
for 64r2 platforms to indicate availability of Xcontext for saving
cpuid, thus freeing Context to be used for saving PGD. This option
was also tied to using a scratch register for storing PGD.

This commit will allow usage of scratch register to store the current
pgd if one can be allocated for the platform, even when
MIPS_PGD_C0_CONTEXT is not set. The cpuid will be kept in the CP0
Context register in this case.

The code to store the current pgd for the TLB miss handler is now
generated in all cases. When scratch register is available, the PGD
is also stored in the scratch register.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---
[ The previous version had a bug that made it hang on mips32
  systems, this version fixes that. ]

 arch/mips/include/asm/mmu_context.h |    7 +-
 arch/mips/mm/tlbex.c                |  142 ++++++++++++++++++++++-------------
 2 files changed, 92 insertions(+), 57 deletions(-)

diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h
index 516e6e9..fc282ef 100644
--- a/arch/mips/include/asm/mmu_context.h
+++ b/arch/mips/include/asm/mmu_context.h
@@ -24,8 +24,6 @@
 #endif /* SMTC */
 #include <asm-generic/mm_hooks.h>
 
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
-
 #define TLBMISS_HANDLER_SETUP_PGD(pgd)					\
 do {									\
 	void (*tlbmiss_handler_setup_pgd)(unsigned long);		\
@@ -36,6 +34,8 @@ do {									\
 	tlbmiss_handler_setup_pgd((unsigned long)(pgd));		\
 } while (0)
 
+
+#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 #define TLBMISS_HANDLER_SETUP()						\
 	do {								\
 		TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);		\
@@ -51,9 +51,6 @@ do {									\
  */
 extern unsigned long pgd_current[];
 
-#define TLBMISS_HANDLER_SETUP_PGD(pgd) \
-	pgd_current[smp_processor_id()] = (unsigned long)(pgd)
-
 #ifdef CONFIG_32BIT
 #define TLBMISS_HANDLER_SETUP()						\
 	write_c0_context((unsigned long) smp_processor_id() << 25);	\
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 9b988c0..b23c744 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -825,11 +825,11 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 	}
 	/* No uasm_i_nop needed here, since the next insn doesn't touch TMP. */
 
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 	if (pgd_reg != -1) {
 		/* pgd is in pgd_reg */
 		UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
 	} else {
+#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 		/*
 		 * &pgd << 11 stored in CONTEXT [23..63].
 		 */
@@ -841,30 +841,30 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		/* 1 0	1 0 1  << 6  xkphys cached */
 		uasm_i_ori(p, ptr, ptr, 0x540);
 		uasm_i_drotr(p, ptr, ptr, 11);
-	}
 #elif defined(CONFIG_SMP)
-# ifdef	 CONFIG_MIPS_MT_SMTC
-	/*
-	 * SMTC uses TCBind value as "CPU" index
-	 */
-	uasm_i_mfc0(p, ptr, C0_TCBIND);
-	uasm_i_dsrl_safe(p, ptr, ptr, 19);
+# ifdef CONFIG_MIPS_MT_SMTC
+		/*
+		 * SMTC uses TCBind value as "CPU" index
+		 */
+		uasm_i_mfc0(p, ptr, C0_TCBIND);
+		uasm_i_dsrl_safe(p, ptr, ptr, 19);
 # else
-	/*
-	 * 64 bit SMP running in XKPHYS has smp_processor_id() << 3
-	 * stored in CONTEXT.
-	 */
-	uasm_i_dmfc0(p, ptr, C0_CONTEXT);
-	uasm_i_dsrl_safe(p, ptr, ptr, 23);
+		/*
+		 * 64 bit SMP running in XKPHYS has smp_processor_id() << 3
+		 * stored in CONTEXT.
+		 */
+		uasm_i_dmfc0(p, ptr, C0_CONTEXT);
+		uasm_i_dsrl_safe(p, ptr, ptr, 23);
 # endif
-	UASM_i_LA_mostly(p, tmp, pgdc);
-	uasm_i_daddu(p, ptr, ptr, tmp);
-	uasm_i_dmfc0(p, tmp, C0_BADVADDR);
-	uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
+		UASM_i_LA_mostly(p, tmp, pgdc);
+		uasm_i_daddu(p, ptr, ptr, tmp);
+		uasm_i_dmfc0(p, tmp, C0_BADVADDR);
+		uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
 #else
-	UASM_i_LA_mostly(p, ptr, pgdc);
-	uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
+		UASM_i_LA_mostly(p, ptr, pgdc);
+		uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
 #endif
+	}
 
 	uasm_l_vmalloc_done(l, *p);
 
@@ -959,31 +959,37 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 static void __cpuinit __maybe_unused
 build_get_pgde32(u32 **p, unsigned int tmp, unsigned int ptr)
 {
-	long pgdc = (long)pgd_current;
+	if (pgd_reg != -1) {
+		/* pgd is in pgd_reg */
+		uasm_i_mfc0(p, ptr, c0_kscratch(), pgd_reg);
+		uasm_i_mfc0(p, tmp, C0_BADVADDR); /* get faulting address */
+	} else {
+		long pgdc = (long)pgd_current;
 
-	/* 32 bit SMP has smp_processor_id() stored in CONTEXT. */
+		/* 32 bit SMP has smp_processor_id() stored in CONTEXT. */
 #ifdef CONFIG_SMP
-#ifdef	CONFIG_MIPS_MT_SMTC
-	/*
-	 * SMTC uses TCBind value as "CPU" index
-	 */
-	uasm_i_mfc0(p, ptr, C0_TCBIND);
-	UASM_i_LA_mostly(p, tmp, pgdc);
-	uasm_i_srl(p, ptr, ptr, 19);
-#else
-	/*
-	 * smp_processor_id() << 3 is stored in CONTEXT.
-	 */
-	uasm_i_mfc0(p, ptr, C0_CONTEXT);
-	UASM_i_LA_mostly(p, tmp, pgdc);
-	uasm_i_srl(p, ptr, ptr, 23);
-#endif
-	uasm_i_addu(p, ptr, tmp, ptr);
+# ifdef CONFIG_MIPS_MT_SMTC
+		/*
+		 * SMTC uses TCBind value as "CPU" index
+		 */
+		uasm_i_mfc0(p, ptr, C0_TCBIND);
+		UASM_i_LA_mostly(p, tmp, pgdc);
+		uasm_i_srl(p, ptr, ptr, 19);
+# else
+		/*
+		 * smp_processor_id() << 3 is stored in CONTEXT.
+		 */
+		uasm_i_mfc0(p, ptr, C0_CONTEXT);
+		UASM_i_LA_mostly(p, tmp, pgdc);
+		uasm_i_srl(p, ptr, ptr, 23);
+# endif
+		uasm_i_addu(p, ptr, tmp, ptr);
 #else
-	UASM_i_LA_mostly(p, ptr, pgdc);
+		UASM_i_LA_mostly(p, ptr, pgdc);
 #endif
-	uasm_i_mfc0(p, tmp, C0_BADVADDR); /* get faulting address */
-	uasm_i_lw(p, ptr, uasm_rel_lo(pgdc), ptr);
+		uasm_i_mfc0(p, tmp, C0_BADVADDR); /* get faulting address */
+		uasm_i_lw(p, ptr, uasm_rel_lo(pgdc), ptr);
+	}
 	uasm_i_srl(p, tmp, tmp, PGDIR_SHIFT); /* get pgd only bits */
 	uasm_i_sll(p, tmp, tmp, PGD_T_LOG2);
 	uasm_i_addu(p, ptr, ptr, tmp); /* add in pgd offset */
@@ -1464,16 +1470,17 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
 u32 handle_tlbl[FASTPATH_SIZE] __cacheline_aligned;
 u32 handle_tlbs[FASTPATH_SIZE] __cacheline_aligned;
 u32 handle_tlbm[FASTPATH_SIZE] __cacheline_aligned;
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 u32 tlbmiss_handler_setup_pgd_array[16] __cacheline_aligned;
 
-static void __cpuinit build_r4000_setup_pgd(void)
+static void __cpuinit build_setup_pgd(void)
 {
 	const int a0 = 4;
-	const int a1 = 5;
+	const int __maybe_unused a1 = 5;
+	const int __maybe_unused a2 = 6;
 	u32 *p = tlbmiss_handler_setup_pgd_array;
-	struct uasm_label *l = labels;
-	struct uasm_reloc *r = relocs;
+#ifndef CONFIG_MIPS_PGD_C0_CONTEXT
+	long pgdc = (long)pgd_current;
+#endif
 
 	memset(tlbmiss_handler_setup_pgd_array, 0, sizeof(tlbmiss_handler_setup_pgd_array));
 	memset(labels, 0, sizeof(labels));
@@ -1481,7 +1488,11 @@ static void __cpuinit build_r4000_setup_pgd(void)
 
 	pgd_reg = allocate_kscratch();
 
+#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 	if (pgd_reg == -1) {
+		struct uasm_label *l = labels;
+		struct uasm_reloc *r = relocs;
+
 		/* PGD << 11 in c0_Context */
 		/*
 		 * If it is a ckseg0 address, convert to a physical
@@ -1503,6 +1514,37 @@ static void __cpuinit build_r4000_setup_pgd(void)
 		uasm_i_jr(&p, 31);
 		UASM_i_MTC0(&p, a0, c0_kscratch(), pgd_reg);
 	}
+#else
+	/* Save PGD to pgd_current[smp_processor_id()] */
+#if defined(CONFIG_SMP)
+# ifdef CONFIG_MIPS_MT_SMTC
+	/*
+	 * SMTC uses TCBind value as "CPU" index
+	 */
+	uasm_i_mfc0(&p, a1, C0_TCBIND);
+	UASM_i_SRL_SAFE(&p, a1, a1, 19);
+# else
+	/*
+	 * smp_processor_id() is in CONTEXT
+	 */
+	UASM_i_MFC0(&p, a1, C0_CONTEXT);
+	UASM_i_SRL_SAFE(&p, a1, a1, 23);
+# endif
+	UASM_i_LA_mostly(&p, a2, pgdc);
+	UASM_i_ADDU(&p, a2, a2, a1);
+	UASM_i_SW(&p, a0, uasm_rel_lo(pgdc), a2);
+#else
+	UASM_i_LA_mostly(&p, a2, pgdc);
+	UASM_i_SW(&p, a0, uasm_rel_lo(pgdc), a2);
+#endif /* SMP */
+	uasm_i_jr(&p, 31);
+
+	/* if pgd_reg is allocated, save PGD also to scratch register */
+	if (pgd_reg != -1)
+		UASM_i_MTC0(&p, a0, c0_kscratch(), pgd_reg);
+	else
+		uasm_i_nop(&p);
+#endif
 	if (p - tlbmiss_handler_setup_pgd_array > ARRAY_SIZE(tlbmiss_handler_setup_pgd_array))
 		panic("tlbmiss_handler_setup_pgd_array space exceeded");
 	uasm_resolve_relocs(relocs, labels);
@@ -1513,7 +1555,6 @@ static void __cpuinit build_r4000_setup_pgd(void)
 		     tlbmiss_handler_setup_pgd_array,
 		     ARRAY_SIZE(tlbmiss_handler_setup_pgd_array));
 }
-#endif
 
 static void __cpuinit
 iPTE_LW(u32 **p, unsigned int pte, unsigned int ptr)
@@ -2195,6 +2236,7 @@ void __cpuinit build_tlb_refill_handler(void)
 		if (!run_once) {
 			if (!cpu_has_local_ebase)
 				build_r3000_tlb_refill_handler();
+			build_setup_pgd();
 			build_r3000_tlb_load_handler();
 			build_r3000_tlb_store_handler();
 			build_r3000_tlb_modify_handler();
@@ -2217,9 +2259,7 @@ void __cpuinit build_tlb_refill_handler(void)
 	default:
 		if (!run_once) {
 			scratch_reg = allocate_kscratch();
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
-			build_r4000_setup_pgd();
-#endif
+			build_setup_pgd();
 			build_r4000_tlb_load_handler();
 			build_r4000_tlb_store_handler();
 			build_r4000_tlb_modify_handler();
@@ -2240,8 +2280,6 @@ void __cpuinit flush_tlb_handlers(void)
 			   (unsigned long)handle_tlbs + sizeof(handle_tlbs));
 	local_flush_icache_range((unsigned long)handle_tlbm,
 			   (unsigned long)handle_tlbm + sizeof(handle_tlbm));
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 	local_flush_icache_range((unsigned long)tlbmiss_handler_setup_pgd_array,
 			   (unsigned long)tlbmiss_handler_setup_pgd_array + sizeof(handle_tlbm));
-#endif
 }
-- 
1.7.9.5

[PATCH UPDATED 4/4] MIPS: Move definition of SMP processor id register to header file

[Jayachandran C]

The definition of the CP0 register used to save the smp processor
id is repicated in many files, move them all to thread_info.h.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---

[ Updated to apply cleanly on the new 3/4 patch ]

 arch/mips/include/asm/mmu_context.h |   17 +++-----
 arch/mips/include/asm/stackframe.h  |   24 +++--------
 arch/mips/include/asm/thread_info.h |   30 +++++++++++++-
 arch/mips/mm/tlbex.c                |   75 +++++------------------------------
 4 files changed, 50 insertions(+), 96 deletions(-)

diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h
index fc282ef..aa59e31 100644
--- a/arch/mips/include/asm/mmu_context.h
+++ b/arch/mips/include/asm/mmu_context.h
@@ -34,15 +34,15 @@ do {									\
 	tlbmiss_handler_setup_pgd((unsigned long)(pgd));		\
 } while (0)
 
-
 #ifdef CONFIG_MIPS_PGD_C0_CONTEXT
 #define TLBMISS_HANDLER_SETUP()						\
 	do {								\
 		TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);		\
-		write_c0_xcontext((unsigned long) smp_processor_id() << 51); \
+		write_c0_xcontext((unsigned long) smp_processor_id() <<	\
+						SMP_CPUID_REGSHIFT);	\
 	} while (0)
 
-#else /* CONFIG_MIPS_PGD_C0_CONTEXT: using  pgd_current*/
+#else /* !CONFIG_MIPS_PGD_C0_CONTEXT: using  pgd_current*/
 
 /*
  * For the fast tlb miss handlers, we keep a per cpu array of pointers
@@ -51,18 +51,11 @@ do {									\
  */
 extern unsigned long pgd_current[];
 
-#ifdef CONFIG_32BIT
-#define TLBMISS_HANDLER_SETUP()						\
-	write_c0_context((unsigned long) smp_processor_id() << 25);	\
-	back_to_back_c0_hazard();					\
-	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
-#endif
-#ifdef CONFIG_64BIT
 #define TLBMISS_HANDLER_SETUP()						\
-	write_c0_context((unsigned long) smp_processor_id() << 26);	\
+	write_c0_context((unsigned long) smp_processor_id() <<		\
+						SMP_CPUID_REGSHIFT);	\
 	back_to_back_c0_hazard();					\
 	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
-#endif
 #endif /* CONFIG_MIPS_PGD_C0_CONTEXT*/
 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 
diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
index a89d1b1..faefe31 100644
--- a/arch/mips/include/asm/stackframe.h
+++ b/arch/mips/include/asm/stackframe.h
@@ -17,6 +17,7 @@
 #include <asm/asmmacro.h>
 #include <asm/mipsregs.h>
 #include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
 
 /*
  * For SMTC kernel, global IE should be left set, and interrupts
@@ -85,21 +86,8 @@
 		.endm
 
 #ifdef CONFIG_SMP
-#ifdef CONFIG_MIPS_MT_SMTC
-#define PTEBASE_SHIFT	19	/* TCBIND */
-#define CPU_ID_REG CP0_TCBIND
-#define CPU_ID_MFC0 mfc0
-#elif defined(CONFIG_MIPS_PGD_C0_CONTEXT)
-#define PTEBASE_SHIFT	48	/* XCONTEXT */
-#define CPU_ID_REG CP0_XCONTEXT
-#define CPU_ID_MFC0 MFC0
-#else
-#define PTEBASE_SHIFT	23	/* CONTEXT */
-#define CPU_ID_REG CP0_CONTEXT
-#define CPU_ID_MFC0 MFC0
-#endif
 		.macro	get_saved_sp	/* SMP variation */
-		CPU_ID_MFC0	k0, CPU_ID_REG
+		ASM_CPUID_MFC0	k0, $SMP_CPUID_REG
 #if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
 		lui	k1, %hi(kernelsp)
 #else
@@ -109,17 +97,17 @@
 		daddiu	k1, %hi(kernelsp)
 		dsll	k1, 16
 #endif
-		LONG_SRL	k0, PTEBASE_SHIFT
+		LONG_SRL	k0, SMP_CPUID_PTRSHIFT
 		LONG_ADDU	k1, k0
 		LONG_L	k1, %lo(kernelsp)(k1)
 		.endm
 
 		.macro	set_saved_sp stackp temp temp2
-		CPU_ID_MFC0	\temp, CPU_ID_REG
-		LONG_SRL	\temp, PTEBASE_SHIFT
+		ASM_CPUID_MFC0	\temp, $SMP_CPUID_REG
+		LONG_SRL	\temp, SMP_CPUID_PTRSHIFT
 		LONG_S	\stackp, kernelsp(\temp)
 		.endm
-#else
+#else /* !CONFIG_SMP */
 		.macro	get_saved_sp	/* Uniprocessor variation */
 #ifdef CONFIG_CPU_JUMP_WORKAROUNDS
 		/*
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index 61215a3..ddff267 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -147,6 +147,34 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_ALLWORK_MASK	(_TIF_NOHZ | _TIF_WORK_MASK |		\
 				 _TIF_WORK_SYSCALL_EXIT)
 
-#endif /* __KERNEL__ */
+/*
+ * We stash processor id into a COP0 register to retrieve it fast
+ * at kernel exception entry.
+ */
+#if defined(CONFIG_MIPS_MT_SMTC)
+#define SMP_CPUID_REG		2, 2	/* TCBIND */
+#define SMP_CPUID_PTRSHIFT	19
+#elif defined(CONFIG_MIPS_PGD_C0_CONTEXT)
+#define SMP_CPUID_REG		20, 0	/* XCONTEXT */
+#define SMP_CPUID_PTRSHIFT	48
+#else
+#define SMP_CPUID_REG		4, 0	/* CONTEXT */
+#define SMP_CPUID_PTRSHIFT	23
+#endif
 
+#ifdef CONFIG_64BIT
+#define SMP_CPUID_REGSHIFT	(SMP_CPUID_PTRSHIFT + 3)
+#else
+#define SMP_CPUID_REGSHIFT	(SMP_CPUID_PTRSHIFT + 2)
+#endif
+
+#ifdef CONFIG_MIPS_MT_SMTC
+#define ASM_CPUID_MFC0		mfc0
+#define UASM_i_CPUID_MFC0	uasm_i_mfc0
+#else
+#define ASM_CPUID_MFC0		MFC0
+#define UASM_i_CPUID_MFC0	UASM_i_MFC0
+#endif
+
+#endif /* __KERNEL__ */
 #endif /* _ASM_THREAD_INFO_H */
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index b23c744..bfff8fe 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -341,10 +341,6 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 {
 	struct work_registers r;
 
-	int smp_processor_id_reg;
-	int smp_processor_id_sel;
-	int smp_processor_id_shift;
-
 	if (scratch_reg >= 0) {
 		/* Save in CPU local C0_KScratch? */
 		UASM_i_MTC0(p, 1, c0_kscratch(), scratch_reg);
@@ -355,25 +351,9 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 	}
 
 	if (num_possible_cpus() > 1) {
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
-		smp_processor_id_shift = 51;
-		smp_processor_id_reg = 20; /* XContext */
-		smp_processor_id_sel = 0;
-#else
-# ifdef CONFIG_32BIT
-		smp_processor_id_shift = 25;
-		smp_processor_id_reg = 4; /* Context */
-		smp_processor_id_sel = 0;
-# endif
-# ifdef CONFIG_64BIT
-		smp_processor_id_shift = 26;
-		smp_processor_id_reg = 4; /* Context */
-		smp_processor_id_sel = 0;
-# endif
-#endif
 		/* Get smp_processor_id */
-		UASM_i_MFC0(p, K0, smp_processor_id_reg, smp_processor_id_sel);
-		UASM_i_SRL_SAFE(p, K0, K0, smp_processor_id_shift);
+		UASM_i_CPUID_MFC0(p, K0, SMP_CPUID_REG);
+		UASM_i_SRL_SAFE(p, K0, K0, SMP_CPUID_REGSHIFT);
 
 		/* handler_reg_save index in K0 */
 		UASM_i_SLL(p, K0, K0, ilog2(sizeof(struct tlb_reg_save)));
@@ -829,7 +809,7 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		/* pgd is in pgd_reg */
 		UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
 	} else {
-#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
+#if defined(CONFIG_MIPS_PGD_C0_CONTEXT)
 		/*
 		 * &pgd << 11 stored in CONTEXT [23..63].
 		 */
@@ -842,20 +822,8 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		uasm_i_ori(p, ptr, ptr, 0x540);
 		uasm_i_drotr(p, ptr, ptr, 11);
 #elif defined(CONFIG_SMP)
-# ifdef CONFIG_MIPS_MT_SMTC
-		/*
-		 * SMTC uses TCBind value as "CPU" index
-		 */
-		uasm_i_mfc0(p, ptr, C0_TCBIND);
-		uasm_i_dsrl_safe(p, ptr, ptr, 19);
-# else
-		/*
-		 * 64 bit SMP running in XKPHYS has smp_processor_id() << 3
-		 * stored in CONTEXT.
-		 */
-		uasm_i_dmfc0(p, ptr, C0_CONTEXT);
-		uasm_i_dsrl_safe(p, ptr, ptr, 23);
-# endif
+		UASM_i_CPUID_MFC0(p, ptr, SMP_CPUID_REG);
+		uasm_i_dsrl_safe(p, ptr, ptr, SMP_CPUID_PTRSHIFT);
 		UASM_i_LA_mostly(p, tmp, pgdc);
 		uasm_i_daddu(p, ptr, ptr, tmp);
 		uasm_i_dmfc0(p, tmp, C0_BADVADDR);
@@ -968,21 +936,9 @@ build_get_pgde32(u32 **p, unsigned int tmp, unsigned int ptr)
 
 		/* 32 bit SMP has smp_processor_id() stored in CONTEXT. */
 #ifdef CONFIG_SMP
-# ifdef CONFIG_MIPS_MT_SMTC
-		/*
-		 * SMTC uses TCBind value as "CPU" index
-		 */
-		uasm_i_mfc0(p, ptr, C0_TCBIND);
+		uasm_i_mfc0(p, ptr, SMP_CPUID_REG);
 		UASM_i_LA_mostly(p, tmp, pgdc);
-		uasm_i_srl(p, ptr, ptr, 19);
-# else
-		/*
-		 * smp_processor_id() << 3 is stored in CONTEXT.
-		 */
-		uasm_i_mfc0(p, ptr, C0_CONTEXT);
-		UASM_i_LA_mostly(p, tmp, pgdc);
-		uasm_i_srl(p, ptr, ptr, 23);
-# endif
+		uasm_i_srl(p, ptr, ptr, SMP_CPUID_PTRSHIFT);
 		uasm_i_addu(p, ptr, tmp, ptr);
 #else
 		UASM_i_LA_mostly(p, ptr, pgdc);
@@ -1515,21 +1471,10 @@ static void __cpuinit build_setup_pgd(void)
 		UASM_i_MTC0(&p, a0, c0_kscratch(), pgd_reg);
 	}
 #else
+#ifdef CONFIG_SMP
 	/* Save PGD to pgd_current[smp_processor_id()] */
-#if defined(CONFIG_SMP)
-# ifdef CONFIG_MIPS_MT_SMTC
-	/*
-	 * SMTC uses TCBind value as "CPU" index
-	 */
-	uasm_i_mfc0(&p, a1, C0_TCBIND);
-	UASM_i_SRL_SAFE(&p, a1, a1, 19);
-# else
-	/*
-	 * smp_processor_id() is in CONTEXT
-	 */
-	UASM_i_MFC0(&p, a1, C0_CONTEXT);
-	UASM_i_SRL_SAFE(&p, a1, a1, 23);
-# endif
+	UASM_i_CPUID_MFC0(&p, a1, SMP_CPUID_REG);
+	UASM_i_SRL_SAFE(&p, a1, a1, SMP_CPUID_PTRSHIFT);
 	UASM_i_LA_mostly(&p, a2, pgdc);
 	UASM_i_ADDU(&p, a2, a2, a1);
 	UASM_i_SW(&p, a0, uasm_rel_lo(pgdc), a2);
-- 
1.7.9.5

Re: [PATCH UPDATED 4/4] MIPS: Move definition of SMP processor id register to header file

[Ralf Baechle]

On Tue, Jun 18, 2013 at 06:15:16PM +0530, Jayachandran C wrote:

> The definition of the CP0 register used to save the smp processor
> id is repicated in many files, move them all to thread_info.h.
> 
> Signed-off-by: Jayachandran C <jchandra@broadcom.com>

This breaks the ip27_defconfig build:

  AS      arch/mips/kernel/genex.o
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S: Assembler messages:
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:199: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:250: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:334: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:377: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:461: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:462: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:463: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:464: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:465: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:466: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:467: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:468: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:469: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:470: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:471: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:479: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:481: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:482: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:483: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:484: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:546: Error: Illegal operands `dmfc0 $26,$4,0'
/home/ralf/src/linux/upstream-sfr/arch/mips/kernel/genex.S:581: Error: Illegal operands `dmfc0 $26,$4,0'
make[4]: *** [arch/mips/kernel/genex.o] Error 1

So I've removed it again for now.

Maciej, I wonder why does gas in MIPS III/IV mode accept

	dmfc0	$reg1, $cp0reg

but not

	dmfc0	$reg1, $cp0reg, 0

The generated code is the same after all.  Same for MIPS I/II mode and mfc0.

  Ralf

Re: [PATCH UPDATED 3/4] MIPS: mm: Use scratch for PGD when !CONFIG_MIPS_PGD_C0_CONTEXT

[Ralf Baechle]

On Tue, Jun 18, 2013 at 06:15:15PM +0530, Jayachandran C wrote:

> Allow usage of scratch register for current pgd even when
> MIPS_PGD_C0_CONTEXT is not configured. MIPS_PGD_C0_CONTEXT is set
> for 64r2 platforms to indicate availability of Xcontext for saving
> cpuid, thus freeing Context to be used for saving PGD. This option
> was also tied to using a scratch register for storing PGD.
> 
> This commit will allow usage of scratch register to store the current
> pgd if one can be allocated for the platform, even when
> MIPS_PGD_C0_CONTEXT is not set. The cpuid will be kept in the CP0
> Context register in this case.
> 
> The code to store the current pgd for the TLB miss handler is now
> generated in all cases. When scratch register is available, the PGD
> is also stored in the scratch register.

I also pulled this one again as it was causing to others.

  Ralf

Re: [PATCH UPDATED 4/4] MIPS: Move definition of SMP processor id register to header file

[Maciej W. Rozycki]

On Thu, 20 Jun 2013, Ralf Baechle wrote:

> So I've removed it again for now.
> 
> Maciej, I wonder why does gas in MIPS III/IV mode accept
> 
> 	dmfc0	$reg1, $cp0reg
> 
> but not
> 
> 	dmfc0	$reg1, $cp0reg, 0
> 
> The generated code is the same after all.  Same for MIPS I/II mode and 
> mfc0.

 The <sel> operand and instruction field was only added to these 
instructions with the MIPS64 ISA (MIPS32 ISA for MFC0/MTC0).  Previously 
processors did not decode this field and consequently the assembler 
notation only supports two operands.

 Since AFAICT the offending pieces are macros I suggest simply dumping the 
redundant ", 0" part, the two-argument form is as you've observed 
equivalent.

  Maciej

[PATCH 2/4] MIPS: Fixup check for invalid scratch register

[Jayachandran C]

The invalid value for scratch register is -1, so update the checks of
the form (scratch_reg > 0) to be (scratch_reg >= 0).  This will fix
the case in Netlogic XLP where the scratch_reg can be 0.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---
 arch/mips/mm/tlbex.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index b687c59..6bac544 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -350,7 +350,7 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 	int smp_processor_id_sel;
 	int smp_processor_id_shift;
 
-	if (scratch_reg > 0) {
+	if (scratch_reg >= 0) {
 		/* Save in CPU local C0_KScratch? */
 		UASM_i_MTC0(p, 1, c0_kscratch, scratch_reg);
 		r.r1 = K0;
@@ -400,7 +400,7 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 
 static void __cpuinit build_restore_work_registers(u32 **p)
 {
-	if (scratch_reg > 0) {
+	if (scratch_reg >= 0) {
 		UASM_i_MFC0(p, 1, c0_kscratch, scratch_reg);
 		return;
 	}
@@ -689,7 +689,7 @@ static __cpuinit void build_restore_pagemask(u32 **p,
 			uasm_i_mtc0(p, 0, C0_PAGEMASK);
 			uasm_il_b(p, r, lid);
 		}
-		if (scratch_reg > 0)
+		if (scratch_reg >= 0)
 			UASM_i_MFC0(p, 1, c0_kscratch, scratch_reg);
 		else
 			UASM_i_LW(p, 1, scratchpad_offset(0), 0);
@@ -945,7 +945,7 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		uasm_i_jr(p, ptr);
 
 		if (mode == refill_scratch) {
-			if (scratch_reg > 0)
+			if (scratch_reg >= 0)
 				UASM_i_MFC0(p, 1, c0_kscratch, scratch_reg);
 			else
 				UASM_i_LW(p, 1, scratchpad_offset(0), 0);
@@ -1302,7 +1302,7 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
 	memset(relocs, 0, sizeof(relocs));
 	memset(final_handler, 0, sizeof(final_handler));
 
-	if ((scratch_reg > 0 || scratchpad_available()) && use_bbit_insns()) {
+	if ((scratch_reg >= 0 || scratchpad_available()) && use_bbit_insns()) {
 		htlb_info = build_fast_tlb_refill_handler(&p, &l, &r, K0, K1,
 							  scratch_reg);
 		vmalloc_mode = refill_scratch;
-- 
1.7.9.5