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ARM: 9106/1: traps: use get_kernel_nofault instead of set_fs()
ARM uses set_fs() and __get_user() to allow the stack dumping code to access possibly invalid pointers carefully. These can be changed to the simpler get_kernel_nofault(), and allow the eventual removal of set_fs(). dump_instr() will print either kernel or user space pointers, depending on how it was called. For dump_mem(), I assume we are only interested in kernel pointers, and the only time that this is called with user_mode(regs)==true is when the regs themselves are unreliable as a result of the condition that caused the trap. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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parent
2423de2e6f
commit
344179fc7e
1 changed files with 16 additions and 31 deletions
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@ -122,17 +122,8 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
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unsigned long top)
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{
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unsigned long first;
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mm_segment_t fs;
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int i;
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/*
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* We need to switch to kernel mode so that we can use __get_user
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* to safely read from kernel space. Note that we now dump the
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* code first, just in case the backtrace kills us.
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*/
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fs = get_fs();
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set_fs(KERNEL_DS);
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printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
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for (first = bottom & ~31; first < top; first += 32) {
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@ -145,7 +136,7 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
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for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
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if (p >= bottom && p < top) {
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unsigned long val;
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if (__get_user(val, (unsigned long *)p) == 0)
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if (get_kernel_nofault(val, (unsigned long *)p))
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sprintf(str + i * 9, " %08lx", val);
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else
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sprintf(str + i * 9, " ????????");
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@ -153,11 +144,9 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
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}
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printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
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}
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set_fs(fs);
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}
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static void __dump_instr(const char *lvl, struct pt_regs *regs)
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static void dump_instr(const char *lvl, struct pt_regs *regs)
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{
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unsigned long addr = instruction_pointer(regs);
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const int thumb = thumb_mode(regs);
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@ -173,10 +162,20 @@ static void __dump_instr(const char *lvl, struct pt_regs *regs)
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for (i = -4; i < 1 + !!thumb; i++) {
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unsigned int val, bad;
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if (thumb)
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bad = get_user(val, &((u16 *)addr)[i]);
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else
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bad = get_user(val, &((u32 *)addr)[i]);
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if (!user_mode(regs)) {
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if (thumb) {
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u16 val16;
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bad = get_kernel_nofault(val16, &((u16 *)addr)[i]);
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val = val16;
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} else {
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bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
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}
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} else {
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if (thumb)
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bad = get_user(val, &((u16 *)addr)[i]);
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else
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bad = get_user(val, &((u32 *)addr)[i]);
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}
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if (!bad)
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p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
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@ -189,20 +188,6 @@ static void __dump_instr(const char *lvl, struct pt_regs *regs)
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printk("%sCode: %s\n", lvl, str);
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}
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static void dump_instr(const char *lvl, struct pt_regs *regs)
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{
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mm_segment_t fs;
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if (!user_mode(regs)) {
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fs = get_fs();
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set_fs(KERNEL_DS);
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__dump_instr(lvl, regs);
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set_fs(fs);
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} else {
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__dump_instr(lvl, regs);
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}
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}
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#ifdef CONFIG_ARM_UNWIND
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static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
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const char *loglvl)
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