powerpc fixes for 5.11 #5

Fix a bad interaction between the scv handling and the fallback L1D flush, which
 could lead to user register corruption. Only affects people using scv (~no one)
 on machines with old firmware that are missing the L1D flush.
 
 Two small selftest fixes.
 
 Thanks to Eirik Fuller, Libor Pechacek, Nicholas Piggin, Sandipan Das, Tulio
 Magno Quites Machado Filho.
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Merge tag 'powerpc-5.11-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - Fix a bad interaction between the scv handling and the fallback L1D
   flush, which could lead to user register corruption. Only affects
   people using scv (~no one) on machines with old firmware that are
   missing the L1D flush.

 - Two small selftest fixes.

Thanks to Eirik Fuller, Libor Pechacek, Nicholas Piggin, Sandipan Das,
and Tulio Magno Quites Machado Filho.

* tag 'powerpc-5.11-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64s: fix scv entry fallback flush vs interrupt
  selftests/powerpc: Only test lwm/stmw on big endian
  selftests/powerpc: Fix exit status of pkey tests

arch/powerpc/include/asm/exception-64s.h

@@ -63,6 +63,12 @@
 	nop;								\
 	nop;
 
+#define SCV_ENTRY_FLUSH_SLOT						\
+	SCV_ENTRY_FLUSH_FIXUP_SECTION;					\
+	nop;								\
+	nop;								\
+	nop;
+
 /*
  * r10 must be free to use, r13 must be paca
  */
@@ -70,6 +76,13 @@
 	STF_ENTRY_BARRIER_SLOT;						\
 	ENTRY_FLUSH_SLOT
 
+/*
+ * r10, ctr must be free to use, r13 must be paca
+ */
+#define SCV_INTERRUPT_TO_KERNEL						\
+	STF_ENTRY_BARRIER_SLOT;						\
+	SCV_ENTRY_FLUSH_SLOT
+
 /*
  * Macros for annotating the expected destination of (h)rfid
  *

arch/powerpc/include/asm/feature-fixups.h

@@ -240,6 +240,14 @@ label##3:					       	\
 	FTR_ENTRY_OFFSET 957b-958b;			\
 	.popsection;
 
+#define SCV_ENTRY_FLUSH_FIXUP_SECTION			\
+957:							\
+	.pushsection __scv_entry_flush_fixup,"a";	\
+	.align 2;					\
+958:							\
+	FTR_ENTRY_OFFSET 957b-958b;			\
+	.popsection;
+
 #define RFI_FLUSH_FIXUP_SECTION				\
 951:							\
 	.pushsection __rfi_flush_fixup,"a";		\
@@ -273,10 +281,12 @@ label##3:					       	\
 
 extern long stf_barrier_fallback;
 extern long entry_flush_fallback;
+extern long scv_entry_flush_fallback;
 extern long __start___stf_entry_barrier_fixup, __stop___stf_entry_barrier_fixup;
 extern long __start___stf_exit_barrier_fixup, __stop___stf_exit_barrier_fixup;
 extern long __start___uaccess_flush_fixup, __stop___uaccess_flush_fixup;
 extern long __start___entry_flush_fixup, __stop___entry_flush_fixup;
+extern long __start___scv_entry_flush_fixup, __stop___scv_entry_flush_fixup;
 extern long __start___rfi_flush_fixup, __stop___rfi_flush_fixup;
 extern long __start___barrier_nospec_fixup, __stop___barrier_nospec_fixup;
 extern long __start__btb_flush_fixup, __stop__btb_flush_fixup;

arch/powerpc/kernel/entry_64.S

@@ -75,7 +75,7 @@ BEGIN_FTR_SECTION
 	bne	.Ltabort_syscall
 END_FTR_SECTION_IFSET(CPU_FTR_TM)
 #endif
-	INTERRUPT_TO_KERNEL
+	SCV_INTERRUPT_TO_KERNEL
 	mr	r10,r1
 	ld	r1,PACAKSAVE(r13)
 	std	r10,0(r1)

arch/powerpc/kernel/exceptions-64s.S

@@ -2993,6 +2993,25 @@ TRAMP_REAL_BEGIN(entry_flush_fallback)
 	ld	r11,PACA_EXRFI+EX_R11(r13)
 	blr
 
+/*
+ * The SCV entry flush happens with interrupts enabled, so it must disable
+ * to prevent EXRFI being clobbered by NMIs (e.g., soft_nmi_common). r10
+ * (containing LR) does not need to be preserved here because scv entry
+ * puts 0 in the pt_regs, CTR can be clobbered for the same reason.
+ */
+TRAMP_REAL_BEGIN(scv_entry_flush_fallback)
+	li	r10,0
+	mtmsrd	r10,1
+	lbz	r10,PACAIRQHAPPENED(r13)
+	ori	r10,r10,PACA_IRQ_HARD_DIS
+	stb	r10,PACAIRQHAPPENED(r13)
+	std	r11,PACA_EXRFI+EX_R11(r13)
+	L1D_DISPLACEMENT_FLUSH
+	ld	r11,PACA_EXRFI+EX_R11(r13)
+	li	r10,MSR_RI
+	mtmsrd	r10,1
+	blr
+
 TRAMP_REAL_BEGIN(rfi_flush_fallback)
 	SET_SCRATCH0(r13);
 	GET_PACA(r13);

arch/powerpc/kernel/vmlinux.lds.S

@@ -145,6 +145,13 @@ SECTIONS
 		__stop___entry_flush_fixup = .;
 	}
 
+	. = ALIGN(8);
+	__scv_entry_flush_fixup : AT(ADDR(__scv_entry_flush_fixup) - LOAD_OFFSET) {
+		__start___scv_entry_flush_fixup = .;
+		*(__scv_entry_flush_fixup)
+		__stop___scv_entry_flush_fixup = .;
+	}
+
 	. = ALIGN(8);
 	__stf_exit_barrier_fixup : AT(ADDR(__stf_exit_barrier_fixup) - LOAD_OFFSET) {
 		__start___stf_exit_barrier_fixup = .;

arch/powerpc/lib/feature-fixups.c

@@ -290,9 +290,6 @@ void do_entry_flush_fixups(enum l1d_flush_type types)
 	long *start, *end;
 	int i;
 
-	start = PTRRELOC(&__start___entry_flush_fixup);
-	end = PTRRELOC(&__stop___entry_flush_fixup);
-
 	instrs[0] = 0x60000000; /* nop */
 	instrs[1] = 0x60000000; /* nop */
 	instrs[2] = 0x60000000; /* nop */
@@ -312,6 +309,8 @@ void do_entry_flush_fixups(enum l1d_flush_type types)
 	if (types & L1D_FLUSH_MTTRIG)
 		instrs[i++] = 0x7c12dba6; /* mtspr TRIG2,r0 (SPR #882) */
 
+	start = PTRRELOC(&__start___entry_flush_fixup);
+	end = PTRRELOC(&__stop___entry_flush_fixup);
 	for (i = 0; start < end; start++, i++) {
 		dest = (void *)start + *start;
 
@@ -328,6 +327,25 @@ void do_entry_flush_fixups(enum l1d_flush_type types)
 		patch_instruction((struct ppc_inst *)(dest + 2), ppc_inst(instrs[2]));
 	}
 
+	start = PTRRELOC(&__start___scv_entry_flush_fixup);
+	end = PTRRELOC(&__stop___scv_entry_flush_fixup);
+	for (; start < end; start++, i++) {
+		dest = (void *)start + *start;
+
+		pr_devel("patching dest %lx\n", (unsigned long)dest);
+
+		patch_instruction((struct ppc_inst *)dest, ppc_inst(instrs[0]));
+
+		if (types == L1D_FLUSH_FALLBACK)
+			patch_branch((struct ppc_inst *)(dest + 1), (unsigned long)&scv_entry_flush_fallback,
+				     BRANCH_SET_LINK);
+		else
+			patch_instruction((struct ppc_inst *)(dest + 1), ppc_inst(instrs[1]));
+
+		patch_instruction((struct ppc_inst *)(dest + 2), ppc_inst(instrs[2]));
+	}
+
+
 	printk(KERN_DEBUG "entry-flush: patched %d locations (%s flush)\n", i,
 		(types == L1D_FLUSH_NONE)       ? "no" :
 		(types == L1D_FLUSH_FALLBACK)   ? "fallback displacement" :

tools/testing/selftests/powerpc/alignment/alignment_handler.c

@@ -443,7 +443,6 @@ int test_alignment_handler_integer(void)
 	LOAD_DFORM_TEST(ldu);
 	LOAD_XFORM_TEST(ldx);
 	LOAD_XFORM_TEST(ldux);
-	LOAD_DFORM_TEST(lmw);
 	STORE_DFORM_TEST(stb);
 	STORE_XFORM_TEST(stbx);
 	STORE_DFORM_TEST(stbu);
@@ -462,7 +461,11 @@ int test_alignment_handler_integer(void)
 	STORE_XFORM_TEST(stdx);
 	STORE_DFORM_TEST(stdu);
 	STORE_XFORM_TEST(stdux);
+
+#ifdef __BIG_ENDIAN__
+	LOAD_DFORM_TEST(lmw);
 	STORE_DFORM_TEST(stmw);
+#endif
 
 	return rc;
 }

tools/testing/selftests/powerpc/mm/pkey_exec_prot.c

@@ -290,5 +290,5 @@ static int test(void)
 
 int main(void)
 {
-	test_harness(test, "pkey_exec_prot");
+	return test_harness(test, "pkey_exec_prot");
 }

tools/testing/selftests/powerpc/mm/pkey_siginfo.c

@@ -329,5 +329,5 @@ static int test(void)
 
 int main(void)
 {
-	test_harness(test, "pkey_siginfo");
+	return test_harness(test, "pkey_siginfo");
 }