Messages in this thread Patch in this message | | | From | Christoph Hellwig <> | Subject | [PATCH] unicore32: use get_kernel_nofault in dump mem and dump_instr | Date | Mon, 20 Jul 2020 13:43:58 +0200 |
| |
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
| |