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Subject[PATCH] unicore32: use get_kernel_nofault in dump mem and dump_instr
Date
Use the proper get_kernel_nofault helper to access an unsafe kernel
pointer without faulting instead of playing with set_fs and get_user.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
arch/unicore32/kernel/traps.c | 28 +++-------------------------
1 file changed, 3 insertions(+), 25 deletions(-)

diff --git a/arch/unicore32/kernel/traps.c b/arch/unicore32/kernel/traps.c
index a3ac01df1a2e43..c1964a4a1edbb0 100644
--- a/arch/unicore32/kernel/traps.c
+++ b/arch/unicore32/kernel/traps.c
@@ -65,17 +65,8 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
unsigned long top)
{
unsigned long first;
- mm_segment_t fs;
int i;

- /*
- * We need to switch to kernel mode so that we can use __get_user
- * to safely read from kernel space. Note that we now dump the
- * code first, just in case the backtrace kills us.
- */
- fs = get_fs();
- set_fs(KERNEL_DS);
-
printk(KERN_DEFAULT "%s%s(0x%08lx to 0x%08lx)\n",
lvl, str, bottom, top);

@@ -89,7 +80,8 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
if (p >= bottom && p < top) {
unsigned long val;
- if (__get_user(val, (unsigned long *)p) == 0)
+ if (get_kernel_nofault(val, (unsigned long *)p)
+ == 0)
sprintf(str + i * 9, " %08lx", val);
else
sprintf(str + i * 9, " ????????");
@@ -97,31 +89,19 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
}
printk(KERN_DEFAULT "%s%04lx:%s\n", lvl, first & 0xffff, str);
}
-
- set_fs(fs);
}

static void dump_instr(const char *lvl, struct pt_regs *regs)
{
unsigned long addr = instruction_pointer(regs);
const int width = 8;
- mm_segment_t fs;
char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
int i;

- /*
- * We need to switch to kernel mode so that we can use __get_user
- * to safely read from kernel space. Note that we now dump the
- * code first, just in case the backtrace kills us.
- */
- fs = get_fs();
- set_fs(KERNEL_DS);
-
for (i = -4; i < 1; i++) {
unsigned int val, bad;

- bad = __get_user(val, &((u32 *)addr)[i]);
-
+ bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
if (!bad)
p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
width, val);
@@ -131,8 +111,6 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
}
}
printk(KERN_DEFAULT "%sCode: %s\n", lvl, str);
-
- set_fs(fs);
}

static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
--
2.27.0
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