diff options
| author |   Ard Biesheuvel <ardb@kernel.org> | 2022-06-30 16:46:54 +0100 |
|---|---|---|
| committer |   Russell King (Oracle) <rmk+kernel@armlinux.org.uk> | 2022-07-06 22:44:49 +0100 |
| commit | e5c46fde75e43c15a29b40e5fc5641727f97ae47 (patch) | |
| tree | 97b2792805da656e88e39826064b1bc192be03a0 /arch/arm/include/asm | |
| parent | ARM: 9213/1: Print message about disabled Spectre workarounds only once (diff) | |
| download | linux-dev-e5c46fde75e43c15a29b40e5fc5641727f97ae47.tar.xz linux-dev-e5c46fde75e43c15a29b40e5fc5641727f97ae47.zip | |
ARM: 9214/1: alignment: advance IT state after emulating Thumb instruction
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: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/include/asm')
| -rw-r--r-- | arch/arm/include/asm/ptrace.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h index 93051e2f402c..1408a6a15d0e 100644 --- a/arch/arm/include/asm/ptrace.h +++ b/arch/arm/include/asm/ptrace.h @@ -163,5 +163,31 @@ 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 |