Messages in this thread | | | Date | Tue, 21 Jul 2020 10:09:20 +0800 (GMT+08:00) | From | "Guan Xuetao" <> | Subject | Re: [PATCH] unicore32: use get_kernel_nofault in dump mem and dump_instr |
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Very good to remove ds/fs in unicore arch. Could u send me full patch for test?
Guan Xuetao
> -----原始邮件----- > 发件人: "Christoph Hellwig" <hch@lst.de> > 发送时间: 2020-07-20 19:43:58 (星期一) > 收件人: gxt@pku.edu.cn > 抄送: linux-kernel@vger.kernel.org > 主题: [PATCH] unicore32: use get_kernel_nofault in dump mem and dump_instr > > 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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