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authorRussell King <rmk+kernel@armlinux.org.uk>2019-08-31 19:01:58 +0300
committerRussell King <rmk+kernel@armlinux.org.uk>2019-10-10 01:29:40 +0300
commit67e15fa5b487adb9b78a92789eeff2d6ec8f5cee (patch)
treeb2d3a83245585d019b2200580c1a75a4cedfab92 /arch/arm/mm
parent4d856f72c10ecb060868ed10ff1b1453943fc6c8 (diff)
downloadlinux-67e15fa5b487adb9b78a92789eeff2d6ec8f5cee.tar.xz
ARM: mm: fix alignment handler faults under memory pressure
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@huawei.com> Fixes: b255188f90e2 ("ARM: fix scheduling while atomic warning in alignment handling code") Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/mm')
-rw-r--r--arch/arm/mm/alignment.c44
1 files changed, 36 insertions, 8 deletions
diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 04b36436cbc0..6587432faf05 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -767,6 +767,36 @@ 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)
{
@@ -774,10 +804,10 @@ 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();
@@ -786,15 +816,14 @@ 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 {
@@ -803,8 +832,7 @@ 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) {