ARM: 9214/1: alignment: advance IT state after emulating Thumb instruction

stable inclusion
from stable-v5.10.132
commit db6e8c30154f390348b5bd6e8028461b90c0876e
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YS3T

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=db6e8c30154f390348b5bd6e8028461b90c0876e

--------------------------------

commit e5c46fde upstream.

After emulating a misaligned load or store issued in Thumb mode, we have
to advance the IT state by hand, or it will get out of sync with the
actual instruction stream, which means we'll end up applying the wrong
condition code to subsequent instructions. This might corrupt the
program state rather catastrophically.

So borrow the it_advance() helper from the probing code, and use it on
CPSR if the emulated instruction is Thumb.

Cc: <stable@vger.kernel.org>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NArd Biesheuvel <ardb@kernel.org>
Signed-off-by: NRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

arch/arm/include/asm/ptrace.h

@@ -164,5 +164,31 @@ static inline unsigned long user_stack_pointer(struct pt_regs *regs)
 		((current_stack_pointer | (THREAD_SIZE - 1)) - 7) - 1;	\
 })
 
+
+/*
+ * Update ITSTATE after normal execution of an IT block instruction.
+ *
+ * The 8 IT state bits are split into two parts in CPSR:
+ *	ITSTATE<1:0> are in CPSR<26:25>
+ *	ITSTATE<7:2> are in CPSR<15:10>
+ */
+static inline unsigned long it_advance(unsigned long cpsr)
+{
+	if ((cpsr & 0x06000400) == 0) {
+		/* ITSTATE<2:0> == 0 means end of IT block, so clear IT state */
+		cpsr &= ~PSR_IT_MASK;
+	} else {
+		/* We need to shift left ITSTATE<4:0> */
+		const unsigned long mask = 0x06001c00;  /* Mask ITSTATE<4:0> */
+		unsigned long it = cpsr & mask;
+		it <<= 1;
+		it |= it >> (27 - 10);  /* Carry ITSTATE<2> to correct place */
+		it &= mask;
+		cpsr &= ~mask;
+		cpsr |= it;
+	}
+	return cpsr;
+}
+
 #endif /* __ASSEMBLY__ */
 #endif

arch/arm/mm/alignment.c

@@ -927,6 +927,9 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (type == TYPE_LDST)
 		do_alignment_finish_ldst(addr, instr, regs, offset);
 
+	if (thumb_mode(regs))
+		regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
+
 	return 0;
 
  bad_or_fault:

arch/arm/probes/decode.h

@@ -14,6 +14,7 @@
 #include <linux/types.h>
 #include <linux/stddef.h>
 #include <asm/probes.h>
+#include <asm/ptrace.h>
 #include <asm/kprobes.h>
 
 void __init arm_probes_decode_init(void);
@@ -35,31 +36,6 @@ void __init find_str_pc_offset(void);
 #endif
 
 
-/*
- * Update ITSTATE after normal execution of an IT block instruction.
- *
- * The 8 IT state bits are split into two parts in CPSR:
- *	ITSTATE<1:0> are in CPSR<26:25>
- *	ITSTATE<7:2> are in CPSR<15:10>
- */
-static inline unsigned long it_advance(unsigned long cpsr)
-	{
-	if ((cpsr & 0x06000400) == 0) {
-		/* ITSTATE<2:0> == 0 means end of IT block, so clear IT state */
-		cpsr &= ~PSR_IT_MASK;
-	} else {
-		/* We need to shift left ITSTATE<4:0> */
-		const unsigned long mask = 0x06001c00;  /* Mask ITSTATE<4:0> */
-		unsigned long it = cpsr & mask;
-		it <<= 1;
-		it |= it >> (27 - 10);  /* Carry ITSTATE<2> to correct place */
-		it &= mask;
-		cpsr &= ~mask;
-		cpsr |= it;
-	}
-	return cpsr;
-}
-
 static inline void __kprobes bx_write_pc(long pcv, struct pt_regs *regs)
 {
 	long cpsr = regs->ARM_cpsr;