powerpc fixes for 5.19 #2

- On 32-bit fix overread/overwrite of thread_struct via ptrace PEEK/POKE.
 
  - Fix softirqs not switching to the softirq stack since we moved irq_exit().
 
  - Force thread size increase when KASAN is enabled to avoid stack overflows.
 
  - On Book3s 64 mark more code as not to be instrumented by KASAN to avoid crashes.
 
  - Exempt __get_wchan() from KASAN checking, as it's inherently racy.
 
  - Fix a recently introduced crash in the papr_scm driver in some configurations.
 
  - Remove include of <generated/compile.h> which is forbidden.
 
 Thanks to: Ariel Miculas, Chen Jingwen, Christophe Leroy, Erhard Furtner, He Ying, Kees
 Cook, Masahiro Yamada, Nageswara R Sastry, Paul Mackerras, Sachin Sant, Vaibhav Jain,
 Wanming Hu.
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCAAxFiEEJFGtCPCthwEv2Y/bUevqPMjhpYAFAmKiBo8THG1wZUBlbGxl
 cm1hbi5pZC5hdQAKCRBR6+o8yOGlgKnND/9wmr3nlA9gaXYCFyfnH5m8u/x7gNFs
 yW150WbcF/9FkhGwGED1kozyCrKqNt9UmBdyEqDjdtHE3ydW3dRnNaBG1wqLzlJd
 BpRUfe8VW5hR7aWkX7Vqzx7bnZACb2bxXv1upYDSeWDF0Bk7szdW2y2ucvRhx8Vv
 8hxDsqIo+AsJV9oP6WSkIMFst0GDVBhbnd70zgu/4j9AYgWlfyJoFRw3vwUMWzS9
 sW6niAZd9PsFboJkBj0LYxPQ6nHXUFEQp5OIn/ZPHmzHW4rnuYao8qgfzWSfxvA1
 LcKLLtvobR9t0jK7SEh7efyOoIY3iprPNtP00jXdvtKMI8gv9bxCNyZBKap1TgQN
 TDexS6ShwcoHTMV6HyR4zA6OqFCn/stsuUNIrywPUvsEBgUPjRLiA2Nzk8wbEGG2
 DXIBqYaNHIr34bRxjQ7K6JzovCGF/VOoRiJqwaAEujz4R164fuw7td/yuflLjL0Q
 JtT9DHXdzskzi+JWxHhsK3sLSHY5BInxt5GNNVsbecgpeizGFjwpGsxhWFOZNrBG
 P8zy7FZ7EzZe1a3qYdFROwZY3kkR4Rtp207ZdgAoWjTrt62ACwyx5HheaxGx+0R1
 LL8LbHPxoWXJyQomMR1zVIzNhivcPqlH+yGkVaZJJY971HxjaCxIbbrH7rNpOf+w
 2l5lxjzq5WrCNQ==
 =Odes
 -----END PGP SIGNATURE-----

Merge tag 'powerpc-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - On 32-bit fix overread/overwrite of thread_struct via ptrace
   PEEK/POKE.

 - Fix softirqs not switching to the softirq stack since we moved
   irq_exit().

 - Force thread size increase when KASAN is enabled to avoid stack
   overflows.

 - On Book3s 64 mark more code as not to be instrumented by KASAN to
   avoid crashes.

 - Exempt __get_wchan() from KASAN checking, as it's inherently racy.

 - Fix a recently introduced crash in the papr_scm driver in some
   configurations.

 - Remove include of <generated/compile.h> which is forbidden.

Thanks to Ariel Miculas, Chen Jingwen, Christophe Leroy, Erhard Furtner,
He Ying, Kees Cook, Masahiro Yamada, Nageswara R Sastry, Paul Mackerras,
Sachin Sant, Vaibhav Jain, and Wanming Hu.

* tag 'powerpc-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/32: Fix overread/overwrite of thread_struct via ptrace
  powerpc/book3e: get rid of #include <generated/compile.h>
  powerpc/kasan: Force thread size increase with KASAN
  powerpc/papr_scm: don't requests stats with '0' sized stats buffer
  powerpc: Don't select HAVE_IRQ_EXIT_ON_IRQ_STACK
  powerpc/kasan: Silence KASAN warnings in __get_wchan()
  powerpc/kasan: Mark more real-mode code as not to be instrumented

arch/powerpc/Kconfig

@@ -223,7 +223,6 @@ config PPC
 	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !HAVE_HARDLOCKUP_DETECTOR_ARCH
 	select HAVE_HW_BREAKPOINT		if PERF_EVENTS && (PPC_BOOK3S || PPC_8xx)
 	select HAVE_IOREMAP_PROT
-	select HAVE_IRQ_EXIT_ON_IRQ_STACK
 	select HAVE_IRQ_TIME_ACCOUNTING
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZMA			if DEFAULT_UIMAGE
@@ -786,7 +785,6 @@ config THREAD_SHIFT
 	range 13 15
 	default "15" if PPC_256K_PAGES
 	default "14" if PPC64
-	default "14" if KASAN
 	default "13"
 	help
 	  Used to define the stack size. The default is almost always what you

arch/powerpc/include/asm/thread_info.h

@@ -14,10 +14,16 @@
 
 #ifdef __KERNEL__
 
-#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT
+#ifdef CONFIG_KASAN
+#define MIN_THREAD_SHIFT	(CONFIG_THREAD_SHIFT + 1)
+#else
+#define MIN_THREAD_SHIFT	CONFIG_THREAD_SHIFT
+#endif
+
+#if defined(CONFIG_VMAP_STACK) && MIN_THREAD_SHIFT < PAGE_SHIFT
 #define THREAD_SHIFT		PAGE_SHIFT
 #else
-#define THREAD_SHIFT		CONFIG_THREAD_SHIFT
+#define THREAD_SHIFT		MIN_THREAD_SHIFT
 #endif
 
 #define THREAD_SIZE		(1 << THREAD_SHIFT)

arch/powerpc/kernel/Makefile

@@ -37,6 +37,8 @@ KASAN_SANITIZE_paca.o := n
 KASAN_SANITIZE_setup_64.o := n
 KASAN_SANITIZE_mce.o := n
 KASAN_SANITIZE_mce_power.o := n
+KASAN_SANITIZE_udbg.o := n
+KASAN_SANITIZE_udbg_16550.o := n
 
 # we have to be particularly careful in ppc64 to exclude code that
 # runs with translations off, as we cannot access the shadow with

arch/powerpc/kernel/process.c

@@ -2158,12 +2158,12 @@ static unsigned long ___get_wchan(struct task_struct *p)
 		return 0;
 
 	do {
-		sp = *(unsigned long *)sp;
+		sp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
 		if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD) ||
 		    task_is_running(p))
 			return 0;
 		if (count > 0) {
-			ip = ((unsigned long *)sp)[STACK_FRAME_LR_SAVE];
+			ip = READ_ONCE_NOCHECK(((unsigned long *)sp)[STACK_FRAME_LR_SAVE]);
 			if (!in_sched_functions(ip))
 				return ip;
 		}

arch/powerpc/kernel/ptrace/ptrace-fpu.c

@@ -17,9 +17,13 @@ int ptrace_get_fpr(struct task_struct *child, int index, unsigned long *data)
 
 #ifdef CONFIG_PPC_FPU_REGS
 	flush_fp_to_thread(child);
-	if (fpidx < (PT_FPSCR - PT_FPR0))
-		memcpy(data, &child->thread.TS_FPR(fpidx), sizeof(long));
-	else
+	if (fpidx < (PT_FPSCR - PT_FPR0)) {
+		if (IS_ENABLED(CONFIG_PPC32))
+			// On 32-bit the index we are passed refers to 32-bit words
+			*data = ((u32 *)child->thread.fp_state.fpr)[fpidx];
+		else
+			memcpy(data, &child->thread.TS_FPR(fpidx), sizeof(long));
+	} else
 		*data = child->thread.fp_state.fpscr;
 #else
 	*data = 0;
@@ -39,9 +43,13 @@ int ptrace_put_fpr(struct task_struct *child, int index, unsigned long data)
 
 #ifdef CONFIG_PPC_FPU_REGS
 	flush_fp_to_thread(child);
-	if (fpidx < (PT_FPSCR - PT_FPR0))
-		memcpy(&child->thread.TS_FPR(fpidx), &data, sizeof(long));
-	else
+	if (fpidx < (PT_FPSCR - PT_FPR0)) {
+		if (IS_ENABLED(CONFIG_PPC32))
+			// On 32-bit the index we are passed refers to 32-bit words
+			((u32 *)child->thread.fp_state.fpr)[fpidx] = data;
+		else
+			memcpy(&child->thread.TS_FPR(fpidx), &data, sizeof(long));
+	} else
 		child->thread.fp_state.fpscr = data;
 #endif
 

arch/powerpc/kernel/ptrace/ptrace.c

@@ -444,4 +444,7 @@ void __init pt_regs_check(void)
 	 * real registers.
 	 */
 	BUILD_BUG_ON(PT_DSCR < sizeof(struct user_pt_regs) / sizeof(unsigned long));
+
+	// ptrace_get/put_fpr() rely on PPC32 and VSX being incompatible
+	BUILD_BUG_ON(IS_ENABLED(CONFIG_PPC32) && IS_ENABLED(CONFIG_VSX));
 }

arch/powerpc/kernel/rtas.c

@@ -993,8 +993,8 @@ int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
  *
  * Return: A pointer to the specified errorlog or NULL if not found.
  */
-struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
-					      uint16_t section_id)
+noinstr struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
+						      uint16_t section_id)
 {
 	struct rtas_ext_event_log_v6 *ext_log =
 		(struct rtas_ext_event_log_v6 *)log->buffer;

arch/powerpc/kexec/crash.c

@@ -224,7 +224,7 @@ void crash_kexec_secondary(struct pt_regs *regs)
 
 /* wait for all the CPUs to hit real mode but timeout if they don't come in */
 #if defined(CONFIG_SMP) && defined(CONFIG_PPC64)
-static void __maybe_unused crash_kexec_wait_realmode(int cpu)
+noinstr static void __maybe_unused crash_kexec_wait_realmode(int cpu)
 {
 	unsigned int msecs;
 	int i;

arch/powerpc/mm/nohash/kaslr_booke.c

@@ -19,7 +19,6 @@
 #include <asm/cacheflush.h>
 #include <asm/kdump.h>
 #include <mm/mmu_decl.h>
-#include <generated/compile.h>
 #include <generated/utsrelease.h>
 
 struct regions {
@@ -37,10 +36,6 @@ struct regions {
 	int reserved_mem_size_cells;
 };
 
-/* Simplified build-specific string for starting entropy. */
-static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
-		LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
-
 struct regions __initdata regions;
 
 static __init void kaslr_get_cmdline(void *fdt)
@@ -71,7 +66,8 @@ static unsigned long __init get_boot_seed(void *fdt)
 {
 	unsigned long hash = 0;
 
-	hash = rotate_xor(hash, build_str, sizeof(build_str));
+	/* build-specific string for starting entropy. */
+	hash = rotate_xor(hash, linux_banner, strlen(linux_banner));
 	hash = rotate_xor(hash, fdt, fdt_totalsize(fdt));
 
 	return hash;

arch/powerpc/platforms/powernv/Makefile

@@ -4,6 +4,7 @@
 # in particular, idle code runs a bunch of things in real mode
 KASAN_SANITIZE_idle.o := n
 KASAN_SANITIZE_pci-ioda.o := n
+KASAN_SANITIZE_pci-ioda-tce.o := n
 # pnv_machine_check_early
 KASAN_SANITIZE_setup.o := n
 

arch/powerpc/platforms/pseries/papr_scm.c

@@ -465,6 +465,9 @@ static int papr_scm_pmu_check_events(struct papr_scm_priv *p, struct nvdimm_pmu
 	u32 available_events;
 	int index, rc = 0;
 
+	if (!p->stat_buffer_len)
+		return -ENOENT;
+
 	available_events = (p->stat_buffer_len  - sizeof(struct papr_scm_perf_stats))
 			/ sizeof(struct papr_scm_perf_stat);
 	if (available_events == 0)