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Date: Fri, 8 Nov 2019 19:49:56 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Jing Xiangfeng <jingxiangfeng@...wei.com>, Russell King <rmk+kernel@...linux.org.uk>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 4.14 08/62] ARM: mm: fix alignment handler faults under memory pressure From: Russell King <rmk+kernel@...linux.org.uk> [ Upstream commit 67e15fa5b487adb9b78a92789eeff2d6ec8f5cee ] When the system has high memory pressure, the page containing the instruction may be paged out. Using probe_kernel_address() means that if the page is swapped out, the resulting page fault will not be handled because page faults are disabled by this function. Use get_user() to read the instruction instead. Reported-by: Jing Xiangfeng <jingxiangfeng@...wei.com> Fixes: b255188f90e2 ("ARM: fix scheduling while atomic warning in alignment handling code") Signed-off-by: Russell King <rmk+kernel@...linux.org.uk> Signed-off-by: Sasha Levin <sashal@...nel.org> --- arch/arm/mm/alignment.c | 44 +++++++++++++++++++++++++++++++++-------- 1 file changed, 36 insertions(+), 8 deletions(-) diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c index 2c96190e018bd..96b17a870b91d 100644 --- a/arch/arm/mm/alignment.c +++ b/arch/arm/mm/alignment.c @@ -768,6 +768,36 @@ do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs, return NULL; } +static int alignment_get_arm(struct pt_regs *regs, u32 *ip, unsigned long *inst) +{ + u32 instr = 0; + int fault; + + if (user_mode(regs)) + fault = get_user(instr, ip); + else + fault = probe_kernel_address(ip, instr); + + *inst = __mem_to_opcode_arm(instr); + + return fault; +} + +static int alignment_get_thumb(struct pt_regs *regs, u16 *ip, u16 *inst) +{ + u16 instr = 0; + int fault; + + if (user_mode(regs)) + fault = get_user(instr, ip); + else + fault = probe_kernel_address(ip, instr); + + *inst = __mem_to_opcode_thumb16(instr); + + return fault; +} + static int do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { @@ -775,10 +805,10 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) unsigned long instr = 0, instrptr; int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); unsigned int type; - unsigned int fault; u16 tinstr = 0; int isize = 4; int thumb2_32b = 0; + int fault; if (interrupts_enabled(regs)) local_irq_enable(); @@ -787,15 +817,14 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) if (thumb_mode(regs)) { u16 *ptr = (u16 *)(instrptr & ~1); - fault = probe_kernel_address(ptr, tinstr); - tinstr = __mem_to_opcode_thumb16(tinstr); + + fault = alignment_get_thumb(regs, ptr, &tinstr); if (!fault) { if (cpu_architecture() >= CPU_ARCH_ARMv7 && IS_T32(tinstr)) { /* Thumb-2 32-bit */ - u16 tinst2 = 0; - fault = probe_kernel_address(ptr + 1, tinst2); - tinst2 = __mem_to_opcode_thumb16(tinst2); + u16 tinst2; + fault = alignment_get_thumb(regs, ptr + 1, &tinst2); instr = __opcode_thumb32_compose(tinstr, tinst2); thumb2_32b = 1; } else { @@ -804,8 +833,7 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) } } } else { - fault = probe_kernel_address((void *)instrptr, instr); - instr = __mem_to_opcode_arm(instr); + fault = alignment_get_arm(regs, (void *)instrptr, &instr); } if (fault) { -- 2.20.1
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