powerpc: Hook in new transactional memory code

mikey · ozbenh · commit bc2a9408fa65 · 2013-02-15T17:02:23.000+11:00
This hooks the new transactional memory code into context switching, FP/VMX/VMX
unavailable and exception return.

Signed-off-by: Matt Evans &lt;matt@ozlabs.org&gt;
Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Signed-off-by: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
@@ -1176,18 +1176,52 @@ fp_unavailable_common:
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	.kernel_fp_unavailable_exception
 	BUG_OPCODE
-1:	bl	.load_up_fpu
+1:
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+BEGIN_FTR_SECTION
+	/* Test if 2 TM state bits are zero.  If non-zero (ie. userspace was in
+	 * transaction), go do TM stuff
+	 */
+	rldicl.	r0, r12, (64-MSR_TS_LG), (64-2)
+	bne-	2f
+END_FTR_SECTION_IFSET(CPU_FTR_TM)
+#endif
+	bl	.load_up_fpu
 	b	fast_exception_return
-
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+2:	/* User process was in a transaction */
+	bl	.save_nvgprs
+	DISABLE_INTS
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	.fp_unavailable_tm
+	b	.ret_from_except
+#endif
 	.align	7
 	.globl altivec_unavailable_common
 altivec_unavailable_common:
 	EXCEPTION_PROLOG_COMMON(0xf20, PACA_EXGEN)
 #ifdef CONFIG_ALTIVEC
 BEGIN_FTR_SECTION
 	beq	1f
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+  BEGIN_FTR_SECTION_NESTED(69)
+	/* Test if 2 TM state bits are zero.  If non-zero (ie. userspace was in
+	 * transaction), go do TM stuff
+	 */
+	rldicl.	r0, r12, (64-MSR_TS_LG), (64-2)
+	bne-	2f
+  END_FTR_SECTION_NESTED(CPU_FTR_TM, CPU_FTR_TM, 69)
+#endif
 	bl	.load_up_altivec
 	b	fast_exception_return
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+2:	/* User process was in a transaction */
+	bl	.save_nvgprs
+	DISABLE_INTS
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	.altivec_unavailable_tm
+	b	.ret_from_except
+#endif
 1:
 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 #endif
@@ -1204,7 +1238,24 @@ vsx_unavailable_common:
 #ifdef CONFIG_VSX
 BEGIN_FTR_SECTION
 	beq	1f
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+  BEGIN_FTR_SECTION_NESTED(69)
+	/* Test if 2 TM state bits are zero.  If non-zero (ie. userspace was in
+	 * transaction), go do TM stuff
+	 */
+	rldicl.	r0, r12, (64-MSR_TS_LG), (64-2)
+	bne-	2f
+  END_FTR_SECTION_NESTED(CPU_FTR_TM, CPU_FTR_TM, 69)
+#endif
 	b	.load_up_vsx
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+2:	/* User process was in a transaction */
+	bl	.save_nvgprs
+	DISABLE_INTS
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	.vsx_unavailable_tm
+	b	.ret_from_except
+#endif
 1:
 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 #endif
@@ -1219,6 +1270,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 tm_unavailable_common:
 	EXCEPTION_PROLOG_COMMON(0xf60, PACA_EXGEN)
 	bl	.save_nvgprs
+	DISABLE_INTS
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	.tm_unavailable_exception
 	b	.ret_from_except
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
@@ -515,7 +515,7 @@ static inline void tm_reclaim_task(struct task_struct *tsk)
 	tm_save_sprs(thr);
 }
 
-static inline void __maybe_unused tm_recheckpoint_new_task(struct task_struct *new)
+static inline void tm_recheckpoint_new_task(struct task_struct *new)
 {
 	unsigned long msr;
 
@@ -590,6 +590,8 @@ struct task_struct *__switch_to(struct task_struct *prev,
 	struct ppc64_tlb_batch *batch;
 #endif
 
+	__switch_to_tm(prev);
+
 #ifdef CONFIG_SMP
 	/* avoid complexity of lazy save/restore of fpu
 	 * by just saving it every time we switch out if
@@ -705,6 +707,9 @@ struct task_struct *__switch_to(struct task_struct *prev,
 	 * of sync. Hard disable here.
 	 */
 	hard_irq_disable();
+
+	tm_recheckpoint_new_task(new);
+
 	last = _switch(old_thread, new_thread);
 
 #ifdef CONFIG_PPC_BOOK3S_64
@@ -1080,7 +1085,6 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
 		regs->msr = MSR_USER32;
 	}
 #endif
-
 	discard_lazy_cpu_state();
 #ifdef CONFIG_VSX
 	current->thread.used_vsr = 0;
@@ -1100,6 +1104,13 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
 	current->thread.spefscr = 0;
 	current->thread.used_spe = 0;
 #endif /* CONFIG_SPE */
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	if (cpu_has_feature(CPU_FTR_TM))
+		regs->msr |= MSR_TM;
+	current->thread.tm_tfhar = 0;
+	current->thread.tm_texasr = 0;
+	current->thread.tm_tfiar = 0;
+#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
 }
 
 #define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
@@ -1029,6 +1029,38 @@ void __kprobes program_check_exception(struct pt_regs *regs)
 		_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
 		return;
 	}
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	if (reason & REASON_TM) {
+		/* This is a TM "Bad Thing Exception" program check.
+		 * This occurs when:
+		 * -  An rfid/hrfid/mtmsrd attempts to cause an illegal
+		 *    transition in TM states.
+		 * -  A trechkpt is attempted when transactional.
+		 * -  A treclaim is attempted when non transactional.
+		 * -  A tend is illegally attempted.
+		 * -  writing a TM SPR when transactional.
+		 */
+		if (!user_mode(regs) &&
+		    report_bug(regs->nip, regs) == BUG_TRAP_TYPE_WARN) {
+			regs->nip += 4;
+			return;
+		}
+		/* If usermode caused this, it's done something illegal and
+		 * gets a SIGILL slap on the wrist.  We call it an illegal
+		 * operand to distinguish from the instruction just being bad
+		 * (e.g. executing a 'tend' on a CPU without TM!); it's an
+		 * illegal /placement/ of a valid instruction.
+		 */
+		if (user_mode(regs)) {
+			_exception(SIGILL, regs, ILL_ILLOPN, regs->nip);
+			return;
+		} else {
+			printk(KERN_EMERG "Unexpected TM Bad Thing exception "
+			       "at %lx (msr 0x%x)\n", regs->nip, reason);
+			die("Unrecoverable exception", regs, SIGABRT);
+		}
+	}
+#endif
 
 	/* We restore the interrupt state now */
 	if (!arch_irq_disabled_regs(regs))
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
@@ -55,6 +55,7 @@
 #include <asm/code-patching.h>
 #include <asm/fadump.h>
 #include <asm/firmware.h>
+#include <asm/tm.h>
 
 #ifdef DEBUG
 #define DBG(fmt...) udbg_printf(fmt)
@@ -1171,6 +1172,21 @@ void flush_hash_page(unsigned long vpn, real_pte_t pte, int psize, int ssize,
 		DBG_LOW(" sub %ld: hash=%lx, hidx=%lx\n", index, slot, hidx);
 		ppc_md.hpte_invalidate(slot, vpn, psize, ssize, local);
 	} pte_iterate_hashed_end();
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	/* Transactions are not aborted by tlbiel, only tlbie.
+	 * Without, syncing a page back to a block device w/ PIO could pick up
+	 * transactional data (bad!) so we force an abort here.  Before the
+	 * sync the page will be made read-only, which will flush_hash_page.
+	 * BIG ISSUE here: if the kernel uses a page from userspace without
+	 * unmapping it first, it may see the speculated version.
+	 */
+	if (local && cpu_has_feature(CPU_FTR_TM) &&
+	    MSR_TM_ACTIVE(current->thread.regs->msr)) {
+		tm_enable();
+		tm_abort(TM_CAUSE_TLBI);
+	}
+#endif
 }
 
 void flush_hash_range(unsigned long number, int local)
