From db6e8c30154f390348b5bd6e8028461b90c0876e Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 30 Jun 2022 16:46:54 +0100 Subject: [PATCH] ARM: 9214/1: alignment: advance IT state after emulating Thumb instruction commit e5c46fde75e43c15a29b40e5fc5641727f97ae47 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: Reviewed-by: Linus Walleij Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King (Oracle) Signed-off-by: Greg Kroah-Hartman --- arch/arm/include/asm/ptrace.h | 26 ++++++++++++++++++++++++++ arch/arm/mm/alignment.c | 3 +++ arch/arm/probes/decode.h | 26 +------------------------- 3 files changed, 30 insertions(+), 25 deletions(-) diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h index 91d6b7856be4b..73c83f4d33b3b 100644 --- a/arch/arm/include/asm/ptrace.h +++ b/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 diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c index ea81e89e77400..bcefe3f51744c 100644 --- a/arch/arm/mm/alignment.c +++ b/arch/arm/mm/alignment.c @@ -935,6 +935,9 @@ 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: diff --git a/arch/arm/probes/decode.h b/arch/arm/probes/decode.h index 9731735989921..facc889d05eee 100644 --- a/arch/arm/probes/decode.h +++ b/arch/arm/probes/decode.h @@ -14,6 +14,7 @@ #include #include #include +#include #include 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; -- 2.47.3