--- /dev/null
+From 7cb68b3f3c5e1edfaa12fb937a3ae76c1617b9c1 Mon Sep 17 00:00:00 2001
+From: Vineet Gupta <vgupta@synopsys.com>
+Date: Tue, 16 Feb 2016 09:42:57 +0530
+Subject: ARC: Assume multiplier is always present
+
+[ Upstream commit 0eca6fdb3193410fbe66b6f064431cc394513e82 ]
+
+It is unlikely that designs running Linux will not have multiplier.
+Further the current support is not complete as tool don't generate a
+multilib w/o multiplier.
+
+Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ arch/arc/Kconfig | 8 --------
+ arch/arc/Makefile | 4 ----
+ arch/arc/kernel/setup.c | 2 --
+ 3 files changed, 14 deletions(-)
+
+diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
+index e983f410135a..a5d8bef65911 100644
+--- a/arch/arc/Kconfig
++++ b/arch/arc/Kconfig
+@@ -278,14 +278,6 @@ config ARC_DCCM_BASE
+ default "0xA0000000"
+ depends on ARC_HAS_DCCM
+
+-config ARC_HAS_HW_MPY
+- bool "Use Hardware Multiplier (Normal or Faster XMAC)"
+- default y
+- help
+- Influences how gcc generates code for MPY operations.
+- If enabled, MPYxx insns are generated, provided by Standard/XMAC
+- Multipler. Otherwise software multipy lib is used
+-
+ choice
+ prompt "MMU Version"
+ default ARC_MMU_V3 if ARC_CPU_770
+diff --git a/arch/arc/Makefile b/arch/arc/Makefile
+index fffaff9c7b2c..8f8d53f08141 100644
+--- a/arch/arc/Makefile
++++ b/arch/arc/Makefile
+@@ -72,10 +72,6 @@ ldflags-$(CONFIG_CPU_BIG_ENDIAN) += -EB
+ # --build-id w/o "-marclinux". Default arc-elf32-ld is OK
+ ldflags-$(upto_gcc44) += -marclinux
+
+-ifndef CONFIG_ARC_HAS_HW_MPY
+- cflags-y += -mno-mpy
+-endif
+-
+ LIBGCC := $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
+
+ # Modules with short calls might break for calls into builtin-kernel
+diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
+index 05131805aa33..3013f3f82b95 100644
+--- a/arch/arc/kernel/setup.c
++++ b/arch/arc/kernel/setup.c
+@@ -232,8 +232,6 @@ static char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len)
+
+ n += scnprintf(buf + n, len - n, "mpy[opt %d] ", opt);
+ }
+- n += scnprintf(buf + n, len - n, "%s",
+- IS_USED_CFG(CONFIG_ARC_HAS_HW_MPY));
+ }
+
+ n += scnprintf(buf + n, len - n, "%s%s%s%s%s%s%s%s\n",
+--
+2.20.1
+
--- /dev/null
+From 5c2c646c52962e98a6df34fe28dc6a2a96ebaee1 Mon Sep 17 00:00:00 2001
+From: Vineet Gupta <vgupta@synopsys.com>
+Date: Wed, 19 Oct 2016 14:38:50 -0700
+Subject: ARC: fix build warning in elf.h
+
+[ Upstream commit 1dec78585328db00e33fb18dc1a6deed0e2095a5 ]
+
+The cast valid since TASK_SIZE * 2 will never actually cause overflow.
+
+| CC fs/binfmt_elf.o
+| In file included from ../include/linux/elf.h:4:0,
+| from ../include/linux/module.h:15,
+| from ../fs/binfmt_elf.c:12:
+| ../fs/binfmt_elf.c: In function load_elf_binar:
+| ../arch/arc/include/asm/elf.h:57:29: warning: integer overflow in expression [-Woverflow]
+| #define ELF_ET_DYN_BASE (2 * TASK_SIZE / 3)
+| ^
+| ../fs/binfmt_elf.c:921:16: note: in expansion of macro ELF_ET_DYN_BASE
+| load_bias = ELF_ET_DYN_BASE - vaddr;
+
+Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ arch/arc/include/asm/elf.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/arc/include/asm/elf.h b/arch/arc/include/asm/elf.h
+index 51a99e25fe33..8ee9113b2f8b 100644
+--- a/arch/arc/include/asm/elf.h
++++ b/arch/arc/include/asm/elf.h
+@@ -55,7 +55,7 @@ extern int elf_check_arch(const struct elf32_hdr *);
+ * the loader. We need to make sure that it is out of the way of the program
+ * that it will "exec", and that there is sufficient room for the brk.
+ */
+-#define ELF_ET_DYN_BASE (2 * TASK_SIZE / 3)
++#define ELF_ET_DYN_BASE (2UL * TASK_SIZE / 3)
+
+ /*
+ * When the program starts, a1 contains a pointer to a function to be
+--
+2.20.1
+
--- /dev/null
+From 509ed98ccdc5e8b4810a74a31efe22c767135d16 Mon Sep 17 00:00:00 2001
+From: Arnd Bergmann <arnd@arndb.de>
+Date: Wed, 21 Feb 2018 14:45:54 -0800
+Subject: bug.h: work around GCC PR82365 in BUG()
+
+[ Upstream commit 173a3efd3edb2ef6ef07471397c5f542a360e9c1 ]
+
+Looking at functions with large stack frames across all architectures
+led me discovering that BUG() suffers from the same problem as
+fortify_panic(), which I've added a workaround for already.
+
+In short, variables that go out of scope by calling a noreturn function
+or __builtin_unreachable() keep using stack space in functions
+afterwards.
+
+A workaround that was identified is to insert an empty assembler
+statement just before calling the function that doesn't return. I'm
+adding a macro "barrier_before_unreachable()" to document this, and
+insert calls to that in all instances of BUG() that currently suffer
+from this problem.
+
+The files that saw the largest change from this had these frame sizes
+before, and much less with my patch:
+
+ fs/ext4/inode.c:82:1: warning: the frame size of 1672 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ fs/ext4/namei.c:434:1: warning: the frame size of 904 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ fs/ext4/super.c:2279:1: warning: the frame size of 1160 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ fs/ext4/xattr.c:146:1: warning: the frame size of 1168 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ fs/f2fs/inode.c:152:1: warning: the frame size of 1424 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ net/netfilter/ipvs/ip_vs_core.c:1195:1: warning: the frame size of 1068 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ net/netfilter/ipvs/ip_vs_core.c:395:1: warning: the frame size of 1084 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ net/netfilter/ipvs/ip_vs_ftp.c:298:1: warning: the frame size of 928 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ net/netfilter/ipvs/ip_vs_ftp.c:418:1: warning: the frame size of 908 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ net/netfilter/ipvs/ip_vs_lblcr.c:718:1: warning: the frame size of 960 bytes is larger than 800 bytes [-Wframe-larger-than=]
+ drivers/net/xen-netback/netback.c:1500:1: warning: the frame size of 1088 bytes is larger than 800 bytes [-Wframe-larger-than=]
+
+In case of ARC and CRIS, it turns out that the BUG() implementation
+actually does return (or at least the compiler thinks it does),
+resulting in lots of warnings about uninitialized variable use and
+leaving noreturn functions, such as:
+
+ block/cfq-iosched.c: In function 'cfq_async_queue_prio':
+ block/cfq-iosched.c:3804:1: error: control reaches end of non-void function [-Werror=return-type]
+ include/linux/dmaengine.h: In function 'dma_maxpq':
+ include/linux/dmaengine.h:1123:1: error: control reaches end of non-void function [-Werror=return-type]
+
+This makes them call __builtin_trap() instead, which should normally
+dump the stack and kill the current process, like some of the other
+architectures already do.
+
+I tried adding barrier_before_unreachable() to panic() and
+fortify_panic() as well, but that had very little effect, so I'm not
+submitting that patch.
+
+Vineet said:
+
+: For ARC, it is double win.
+:
+: 1. Fixes 3 -Wreturn-type warnings
+:
+: | ../net/core/ethtool.c:311:1: warning: control reaches end of non-void function
+: [-Wreturn-type]
+: | ../kernel/sched/core.c:3246:1: warning: control reaches end of non-void function
+: [-Wreturn-type]
+: | ../include/linux/sunrpc/svc_xprt.h:180:1: warning: control reaches end of
+: non-void function [-Wreturn-type]
+:
+: 2. bloat-o-meter reports code size improvements as gcc elides the
+: generated code for stack return.
+
+Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
+Link: http://lkml.kernel.org/r/20171219114112.939391-1-arnd@arndb.de
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Acked-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc]
+Tested-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc]
+Cc: Mikael Starvik <starvik@axis.com>
+Cc: Jesper Nilsson <jesper.nilsson@axis.com>
+Cc: Tony Luck <tony.luck@intel.com>
+Cc: Fenghua Yu <fenghua.yu@intel.com>
+Cc: Geert Uytterhoeven <geert@linux-m68k.org>
+Cc: "David S. Miller" <davem@davemloft.net>
+Cc: Christopher Li <sparse@chrisli.org>
+Cc: Thomas Gleixner <tglx@linutronix.de>
+Cc: Peter Zijlstra <peterz@infradead.org>
+Cc: Kees Cook <keescook@chromium.org>
+Cc: Ingo Molnar <mingo@kernel.org>
+Cc: Josh Poimboeuf <jpoimboe@redhat.com>
+Cc: Will Deacon <will.deacon@arm.com>
+Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
+Cc: Mark Rutland <mark.rutland@arm.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ arch/arc/include/asm/bug.h | 3 ++-
+ arch/cris/include/arch-v10/arch/bug.h | 11 +++++++++--
+ arch/ia64/include/asm/bug.h | 6 +++++-
+ arch/m68k/include/asm/bug.h | 3 +++
+ arch/sparc/include/asm/bug.h | 6 +++++-
+ include/asm-generic/bug.h | 1 +
+ include/linux/compiler-gcc.h | 15 ++++++++++++++-
+ include/linux/compiler.h | 5 +++++
+ 8 files changed, 44 insertions(+), 6 deletions(-)
+
+diff --git a/arch/arc/include/asm/bug.h b/arch/arc/include/asm/bug.h
+index ea022d47896c..21ec82466d62 100644
+--- a/arch/arc/include/asm/bug.h
++++ b/arch/arc/include/asm/bug.h
+@@ -23,7 +23,8 @@ void die(const char *str, struct pt_regs *regs, unsigned long address);
+
+ #define BUG() do { \
+ pr_warn("BUG: failure at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
+- dump_stack(); \
++ barrier_before_unreachable(); \
++ __builtin_trap(); \
+ } while (0)
+
+ #define HAVE_ARCH_BUG
+diff --git a/arch/cris/include/arch-v10/arch/bug.h b/arch/cris/include/arch-v10/arch/bug.h
+index 3485d6b34bb0..06701ac0596f 100644
+--- a/arch/cris/include/arch-v10/arch/bug.h
++++ b/arch/cris/include/arch-v10/arch/bug.h
+@@ -43,18 +43,25 @@ struct bug_frame {
+ * not be used like this with newer versions of gcc.
+ */
+ #define BUG() \
++do { \
+ __asm__ __volatile__ ("clear.d [" __stringify(BUG_MAGIC) "]\n\t"\
+ "movu.w " __stringify(__LINE__) ",$r0\n\t"\
+ "jump 0f\n\t" \
+ ".section .rodata\n" \
+ "0:\t.string \"" __FILE__ "\"\n\t" \
+- ".previous")
++ ".previous"); \
++ unreachable(); \
++} while (0)
+ #endif
+
+ #else
+
+ /* This just causes an oops. */
+-#define BUG() (*(int *)0 = 0)
++#define BUG() \
++do { \
++ barrier_before_unreachable(); \
++ __builtin_trap(); \
++} while (0)
+
+ #endif
+
+diff --git a/arch/ia64/include/asm/bug.h b/arch/ia64/include/asm/bug.h
+index 823616b5020b..19067821249f 100644
+--- a/arch/ia64/include/asm/bug.h
++++ b/arch/ia64/include/asm/bug.h
+@@ -3,7 +3,11 @@
+
+ #ifdef CONFIG_BUG
+ #define ia64_abort() __builtin_trap()
+-#define BUG() do { printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); ia64_abort(); } while (0)
++#define BUG() do { \
++ printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); \
++ barrier_before_unreachable(); \
++ ia64_abort(); \
++} while (0)
+
+ /* should this BUG be made generic? */
+ #define HAVE_ARCH_BUG
+diff --git a/arch/m68k/include/asm/bug.h b/arch/m68k/include/asm/bug.h
+index ef9a2e47352f..21ddbf925e22 100644
+--- a/arch/m68k/include/asm/bug.h
++++ b/arch/m68k/include/asm/bug.h
+@@ -7,16 +7,19 @@
+ #ifndef CONFIG_SUN3
+ #define BUG() do { \
+ printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); \
++ barrier_before_unreachable(); \
+ __builtin_trap(); \
+ } while (0)
+ #else
+ #define BUG() do { \
+ printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); \
++ barrier_before_unreachable(); \
+ panic("BUG!"); \
+ } while (0)
+ #endif
+ #else
+ #define BUG() do { \
++ barrier_before_unreachable(); \
+ __builtin_trap(); \
+ } while (0)
+ #endif
+diff --git a/arch/sparc/include/asm/bug.h b/arch/sparc/include/asm/bug.h
+index eaa8f8d38125..fa85cac0285c 100644
+--- a/arch/sparc/include/asm/bug.h
++++ b/arch/sparc/include/asm/bug.h
+@@ -8,10 +8,14 @@
+ void do_BUG(const char *file, int line);
+ #define BUG() do { \
+ do_BUG(__FILE__, __LINE__); \
++ barrier_before_unreachable(); \
+ __builtin_trap(); \
+ } while (0)
+ #else
+-#define BUG() __builtin_trap()
++#define BUG() do { \
++ barrier_before_unreachable(); \
++ __builtin_trap(); \
++} while (0)
+ #endif
+
+ #define HAVE_ARCH_BUG
+diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
+index 630dd2372238..09aa521a0085 100644
+--- a/include/asm-generic/bug.h
++++ b/include/asm-generic/bug.h
+@@ -47,6 +47,7 @@ struct bug_entry {
+ #ifndef HAVE_ARCH_BUG
+ #define BUG() do { \
+ printk("BUG: failure at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
++ barrier_before_unreachable(); \
+ panic("BUG!"); \
+ } while (0)
+ #endif
+diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
+index 143d40e8a1ea..af8b4a879934 100644
+--- a/include/linux/compiler-gcc.h
++++ b/include/linux/compiler-gcc.h
+@@ -206,6 +206,15 @@
+ #endif /* GCC_VERSION >= 40300 */
+
+ #if GCC_VERSION >= 40500
++/*
++ * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
++ * confuse the stack allocation in gcc, leading to overly large stack
++ * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
++ *
++ * Adding an empty inline assembly before it works around the problem
++ */
++#define barrier_before_unreachable() asm volatile("")
++
+ /*
+ * Mark a position in code as unreachable. This can be used to
+ * suppress control flow warnings after asm blocks that transfer
+@@ -215,7 +224,11 @@
+ * this in the preprocessor, but we can live with this because they're
+ * unreleased. Really, we need to have autoconf for the kernel.
+ */
+-#define unreachable() __builtin_unreachable()
++#define unreachable() \
++ do { \
++ barrier_before_unreachable(); \
++ __builtin_unreachable(); \
++ } while (0)
+
+ /* Mark a function definition as prohibited from being cloned. */
+ #define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
+diff --git a/include/linux/compiler.h b/include/linux/compiler.h
+index 0db1fa621d8a..ed772311ec1f 100644
+--- a/include/linux/compiler.h
++++ b/include/linux/compiler.h
+@@ -175,6 +175,11 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
+ # define barrier_data(ptr) barrier()
+ #endif
+
++/* workaround for GCC PR82365 if needed */
++#ifndef barrier_before_unreachable
++# define barrier_before_unreachable() do { } while (0)
++#endif
++
+ /* Unreachable code */
+ #ifndef unreachable
+ # define unreachable() do { } while (1)
+--
+2.20.1
+
--- /dev/null
+From 00f3b19db1ca923e047437123f3a264922a3fc7f Mon Sep 17 00:00:00 2001
+From: Arnd Bergmann <arnd@arndb.de>
+Date: Wed, 23 Aug 2017 16:44:51 +0200
+Subject: mfd: omap-usb-tll: Fix register offsets
+
+[ Upstream commit 993dc737c0996c163325961fb62a0ed9fd0308b4 ]
+
+gcc-8 notices that the register number calculation is wrong
+when the offset is an 'u8' but the number is larger than 256:
+
+drivers/mfd/omap-usb-tll.c: In function 'omap_tll_init':
+drivers/mfd/omap-usb-tll.c:90:46: error: overflow in conversion from 'int' to 'u8 {aka unsigned char}' chages value from 'i * 256 + 2070' to '22' [-Werror=overflow]
+
+This addresses it by always using a 32-bit offset number for
+the register. This is apparently an old problem that previous
+compilers did not find.
+
+Fixes: 16fa3dc75c22 ("mfd: omap-usb-tll: HOST TLL platform driver")
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Signed-off-by: Lee Jones <lee.jones@linaro.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ drivers/mfd/omap-usb-tll.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
+index fe51e9709210..1093d8ad232b 100644
+--- a/drivers/mfd/omap-usb-tll.c
++++ b/drivers/mfd/omap-usb-tll.c
+@@ -129,12 +129,12 @@ static inline u32 usbtll_read(void __iomem *base, u32 reg)
+ return readl_relaxed(base + reg);
+ }
+
+-static inline void usbtll_writeb(void __iomem *base, u8 reg, u8 val)
++static inline void usbtll_writeb(void __iomem *base, u32 reg, u8 val)
+ {
+ writeb_relaxed(val, base + reg);
+ }
+
+-static inline u8 usbtll_readb(void __iomem *base, u8 reg)
++static inline u8 usbtll_readb(void __iomem *base, u32 reg)
+ {
+ return readb_relaxed(base + reg);
+ }
+--
+2.20.1
+
--- /dev/null
+From 08cf23029b9e2deeff36576b6f227cca81daec5e Mon Sep 17 00:00:00 2001
+From: Manuel Lauss <manuel.lauss@gmail.com>
+Date: Mon, 14 Aug 2017 12:21:48 +0200
+Subject: MIPS: math-emu: do not use bools for arithmetic
+
+[ Upstream commit 8535f2ba0a9b971df62a5890699b9dfe2e0d5580 ]
+
+GCC-7 complains about a boolean value being used with an arithmetic
+AND:
+
+arch/mips/math-emu/cp1emu.c: In function 'cop1Emulate':
+arch/mips/math-emu/cp1emu.c:838:14: warning: '~' on a boolean expression [-Wbool-operation]
+ fpr = (x) & ~(cop1_64bit(xcp) == 0); \
+ ^
+arch/mips/math-emu/cp1emu.c:1068:3: note: in expansion of macro 'DITOREG'
+ DITOREG(dval, MIPSInst_RT(ir));
+ ^~~~~~~
+arch/mips/math-emu/cp1emu.c:838:14: note: did you mean to use logical not?
+ fpr = (x) & ~(cop1_64bit(xcp) == 0); \
+
+Since cop1_64bit() returns and int, just flip the LSB.
+
+Suggested-by: Maciej W. Rozycki <macro@imgtec.com>
+Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
+Reviewed-by: Maciej W. Rozycki <macro@imgtec.com>
+Cc: linux-mips@linux-mips.org
+Patchwork: https://patchwork.linux-mips.org/patch/17058/
+Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ arch/mips/math-emu/cp1emu.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
+index 89d05de8040a..011b9b9574f1 100644
+--- a/arch/mips/math-emu/cp1emu.c
++++ b/arch/mips/math-emu/cp1emu.c
+@@ -829,12 +829,12 @@ do { \
+ } while (0)
+
+ #define DIFROMREG(di, x) \
+- ((di) = get_fpr64(&ctx->fpr[(x) & ~(cop1_64bit(xcp) == 0)], 0))
++ ((di) = get_fpr64(&ctx->fpr[(x) & ~(cop1_64bit(xcp) ^ 1)], 0))
+
+ #define DITOREG(di, x) \
+ do { \
+ unsigned fpr, i; \
+- fpr = (x) & ~(cop1_64bit(xcp) == 0); \
++ fpr = (x) & ~(cop1_64bit(xcp) ^ 1); \
+ set_fpr64(&ctx->fpr[fpr], 0, di); \
+ for (i = 1; i < ARRAY_SIZE(ctx->fpr[x].val64); i++) \
+ set_fpr64(&ctx->fpr[fpr], i, 0); \
+--
+2.20.1
+
--- /dev/null
+From 9d788727b95af099a964d285afe0a6726ebf85d5 Mon Sep 17 00:00:00 2001
+From: Paul Burton <paul.burton@mips.com>
+Date: Mon, 20 Aug 2018 15:36:18 -0700
+Subject: MIPS: Workaround GCC __builtin_unreachable reordering bug
+
+[ Upstream commit 906d441febc0de974b2a6ef848a8f058f3bfada3 ]
+
+Some versions of GCC for the MIPS architecture suffer from a bug which
+can lead to instructions from beyond an unreachable statement being
+incorrectly reordered into earlier branch delay slots if the unreachable
+statement is the only content of a case in a switch statement. This can
+lead to seemingly random behaviour, such as invalid memory accesses from
+incorrectly reordered loads or stores, and link failures on microMIPS
+builds.
+
+See this potential GCC fix for details:
+
+ https://gcc.gnu.org/ml/gcc-patches/2015-09/msg00360.html
+
+Runtime problems resulting from this bug were initially observed using a
+maltasmvp_defconfig v4.4 kernel built using GCC 4.9.2 (from a Codescape
+SDK 2015.06-05 toolchain), with the result being an address exception
+taken after log messages about the L1 caches (during probe of the L2
+cache):
+
+ Initmem setup node 0 [mem 0x0000000080000000-0x000000009fffffff]
+ VPE topology {2,2} total 4
+ Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
+ Primary data cache 64kB, 4-way, PIPT, no aliases, linesize 32 bytes
+ <AdEL exception here>
+
+This is early enough that the kernel exception vectors are not in use,
+so any further output depends upon the bootloader. This is reproducible
+in QEMU where no further output occurs - ie. the system hangs here.
+Given the nature of the bug it may potentially be hit with differing
+symptoms. The bug is known to affect GCC versions as recent as 7.3, and
+it is unclear whether GCC 8 fixed it or just happens not to encounter
+the bug in the testcase found at the link above due to differing
+optimizations.
+
+This bug can be worked around by placing a volatile asm statement, which
+GCC is prevented from reordering past, prior to the
+__builtin_unreachable call.
+
+That was actually done already for other reasons by commit 173a3efd3edb
+("bug.h: work around GCC PR82365 in BUG()"), but creates problems for
+microMIPS builds due to the lack of a .insn directive. The microMIPS ISA
+allows for interlinking with regular MIPS32 code by repurposing bit 0 of
+the program counter as an ISA mode bit. To switch modes one changes the
+value of this bit in the PC. However typical branch instructions encode
+their offsets as multiples of 2-byte instruction halfwords, which means
+they cannot change ISA mode - this must be done using either an indirect
+branch (a jump-register in MIPS terminology) or a dedicated jalx
+instruction. In order to ensure that regular branches don't attempt to
+target code in a different ISA which they can't actually switch to, the
+linker will check that branch targets are code in the same ISA as the
+branch.
+
+Unfortunately our empty asm volatile statements don't qualify as code,
+and the link for microMIPS builds fails with errors such as:
+
+ arch/mips/mm/dma-default.s:3265: Error: branch to a symbol in another ISA mode
+ arch/mips/mm/dma-default.s:5027: Error: branch to a symbol in another ISA mode
+
+Resolve this by adding a .insn directive within the asm statement which
+declares that what comes next is code. This may or may not be true,
+since we don't really know what comes next, but as this code is in an
+unreachable path anyway that doesn't matter since we won't execute it.
+
+We do this in asm/compiler.h & select CONFIG_HAVE_ARCH_COMPILER_H in
+order to have this included by linux/compiler_types.h after
+linux/compiler-gcc.h. This will result in asm/compiler.h being included
+in all C compilations via the -include linux/compiler_types.h argument
+in c_flags, which should be harmless.
+
+Signed-off-by: Paul Burton <paul.burton@mips.com>
+Fixes: 173a3efd3edb ("bug.h: work around GCC PR82365 in BUG()")
+Patchwork: https://patchwork.linux-mips.org/patch/20270/
+Cc: James Hogan <jhogan@kernel.org>
+Cc: Ralf Baechle <ralf@linux-mips.org>
+Cc: Arnd Bergmann <arnd@arndb.de>
+Cc: linux-mips@linux-mips.org
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ arch/mips/Kconfig | 1 +
+ arch/mips/include/asm/compiler.h | 35 ++++++++++++++++++++++++++++++++
+ 2 files changed, 36 insertions(+)
+
+diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
+index 333ea0389adb..687a3eb8d4d9 100644
+--- a/arch/mips/Kconfig
++++ b/arch/mips/Kconfig
+@@ -13,6 +13,7 @@ config MIPS
+ select HAVE_OPROFILE
+ select HAVE_PERF_EVENTS
+ select PERF_USE_VMALLOC
++ select HAVE_ARCH_COMPILER_H
+ select HAVE_ARCH_KGDB
+ select HAVE_ARCH_SECCOMP_FILTER
+ select HAVE_ARCH_TRACEHOOK
+diff --git a/arch/mips/include/asm/compiler.h b/arch/mips/include/asm/compiler.h
+index e081a265f422..cc2eb1b06050 100644
+--- a/arch/mips/include/asm/compiler.h
++++ b/arch/mips/include/asm/compiler.h
+@@ -8,6 +8,41 @@
+ #ifndef _ASM_COMPILER_H
+ #define _ASM_COMPILER_H
+
++/*
++ * With GCC 4.5 onwards we can use __builtin_unreachable to indicate to the
++ * compiler that a particular code path will never be hit. This allows it to be
++ * optimised out of the generated binary.
++ *
++ * Unfortunately at least GCC 4.6.3 through 7.3.0 inclusive suffer from a bug
++ * that can lead to instructions from beyond an unreachable statement being
++ * incorrectly reordered into earlier delay slots if the unreachable statement
++ * is the only content of a case in a switch statement. This can lead to
++ * seemingly random behaviour, such as invalid memory accesses from incorrectly
++ * reordered loads or stores. See this potential GCC fix for details:
++ *
++ * https://gcc.gnu.org/ml/gcc-patches/2015-09/msg00360.html
++ *
++ * It is unclear whether GCC 8 onwards suffer from the same issue - nothing
++ * relevant is mentioned in GCC 8 release notes and nothing obviously relevant
++ * stands out in GCC commit logs, but these newer GCC versions generate very
++ * different code for the testcase which doesn't exhibit the bug.
++ *
++ * GCC also handles stack allocation suboptimally when calling noreturn
++ * functions or calling __builtin_unreachable():
++ *
++ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
++ *
++ * We work around both of these issues by placing a volatile asm statement,
++ * which GCC is prevented from reordering past, prior to __builtin_unreachable
++ * calls.
++ *
++ * The .insn statement is required to ensure that any branches to the
++ * statement, which sadly must be kept due to the asm statement, are known to
++ * be branches to code and satisfy linker requirements for microMIPS kernels.
++ */
++#undef barrier_before_unreachable
++#define barrier_before_unreachable() asm volatile(".insn")
++
+ #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+ #define GCC_IMM_ASM() "n"
+ #define GCC_REG_ACCUM "$0"
+--
+2.20.1
+
usb-gadget-fusb300_udc-fix-memory-leak-of-fusb300-ep.patch
usb-gadget-udc-lpc32xx-allocate-descriptor-with-gfp_.patch
scsi-hpsa-correct-ioaccel2-chaining.patch
+arc-assume-multiplier-is-always-present.patch
+arc-fix-build-warning-in-elf.h.patch
+mips-math-emu-do-not-use-bools-for-arithmetic.patch
+mfd-omap-usb-tll-fix-register-offsets.patch
+swiotlb-make-linux-swiotlb.h-standalone-includible.patch
+bug.h-work-around-gcc-pr82365-in-bug.patch
+mips-workaround-gcc-__builtin_unreachable-reordering.patch
--- /dev/null
+From b13698a147aaf3d2dca1e5cb5e7857fcd4773263 Mon Sep 17 00:00:00 2001
+From: Thierry Reding <treding@nvidia.com>
+Date: Wed, 1 Jul 2015 14:17:58 +0200
+Subject: swiotlb: Make linux/swiotlb.h standalone includible
+
+[ Upstream commit 386744425e35e04984c6e741c7750fd6eef1a9df ]
+
+This header file uses the enum dma_data_direction and struct page types
+without explicitly including the corresponding header files. This makes
+it rely on the includer to have included the proper headers before.
+
+To fix this, include linux/dma-direction.h and forward-declare struct
+page. The swiotlb_free() function is also annotated __init, therefore
+requires linux/init.h to be included as well.
+
+Signed-off-by: Thierry Reding <treding@nvidia.com>
+Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ include/linux/swiotlb.h | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
+index e7a018eaf3a2..017fced60242 100644
+--- a/include/linux/swiotlb.h
++++ b/include/linux/swiotlb.h
+@@ -1,10 +1,13 @@
+ #ifndef __LINUX_SWIOTLB_H
+ #define __LINUX_SWIOTLB_H
+
++#include <linux/dma-direction.h>
++#include <linux/init.h>
+ #include <linux/types.h>
+
+ struct device;
+ struct dma_attrs;
++struct page;
+ struct scatterlist;
+
+ extern int swiotlb_force;
+--
+2.20.1
+
projects / thirdparty / kernel / stable-queue.git / commitdiff
