sh: Allow user control over misaligned fixup handling
This patch brings the SH4 misaligned trap handler in line with what happens on ARM: Add a /proc/cpu/alignment which can be read from to get alignment trap statistics and written to to influence the behaviour of the alignment trap handling. The value to write is a bitfield, which has the following meaning: 1 warn, 2 fixup, 4 signal In addition, we add a /proc/cpu/kernel_alignment, to enable or disable warnings in case of kernel code causing alignment errors. Signed-off by: Andre Draszik <andre.draszik@st.com> Signed-off-by: Stuart Menefy <stuart.menefy@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Andre Draszik
Paul Mundt
Родитель
9a4af027a0
Коммит
7436cde6b2
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@ -24,6 +24,7 @@
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#include <linux/kdebug.h>
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#include <linux/kexec.h>
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#include <linux/limits.h>
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#include <linux/proc_fs.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <asm/fpu.h>
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@ -44,6 +45,87 @@
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#define TRAP_ILLEGAL_SLOT_INST 13
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#endif
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static unsigned long se_user;
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static unsigned long se_sys;
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static unsigned long se_skipped;
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static unsigned long se_half;
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static unsigned long se_word;
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static unsigned long se_dword;
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static unsigned long se_multi;
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/* bitfield: 1: warn 2: fixup 4: signal -> combinations 2|4 && 1|2|4 are not
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valid! */
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static int se_usermode = 3;
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/* 0: no warning 1: print a warning message */
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static int se_kernmode_warn = 1;
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#ifdef CONFIG_PROC_FS
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static const char *se_usermode_action[] = {
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"ignored",
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"warn",
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"fixup",
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"fixup+warn",
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"signal",
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"signal+warn"
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};
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static int
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proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
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void *data)
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{
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char *p = page;
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int len;
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p += sprintf(p, "User:\t\t%lu\n", se_user);
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p += sprintf(p, "System:\t\t%lu\n", se_sys);
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p += sprintf(p, "Skipped:\t%lu\n", se_skipped);
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p += sprintf(p, "Half:\t\t%lu\n", se_half);
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p += sprintf(p, "Word:\t\t%lu\n", se_word);
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p += sprintf(p, "DWord:\t\t%lu\n", se_dword);
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p += sprintf(p, "Multi:\t\t%lu\n", se_multi);
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p += sprintf(p, "User faults:\t%i (%s)\n", se_usermode,
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se_usermode_action[se_usermode]);
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p += sprintf(p, "Kernel faults:\t%i (fixup%s)\n", se_kernmode_warn,
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se_kernmode_warn ? "+warn" : "");
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len = (p - page) - off;
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if (len < 0)
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len = 0;
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*eof = (len <= count) ? 1 : 0;
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*start = page + off;
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return len;
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}
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static int proc_alignment_write(struct file *file, const char __user *buffer,
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unsigned long count, void *data)
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{
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char mode;
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if (count > 0) {
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if (get_user(mode, buffer))
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return -EFAULT;
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if (mode >= '0' && mode <= '5')
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se_usermode = mode - '0';
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}
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return count;
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}
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static int proc_alignment_kern_write(struct file *file, const char __user *buffer,
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unsigned long count, void *data)
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{
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char mode;
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if (count > 0) {
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if (get_user(mode, buffer))
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return -EFAULT;
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if (mode >= '0' && mode <= '1')
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se_kernmode_warn = mode - '0';
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}
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return count;
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}
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#endif
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static void dump_mem(const char *str, unsigned long bottom, unsigned long top)
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{
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unsigned long p;
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@ -194,6 +276,13 @@ static int handle_unaligned_ins(insn_size_t instruction, struct pt_regs *regs,
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count = 1<<(instruction&3);
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switch (count) {
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case 1: se_half += 1; break;
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case 2: se_word += 1; break;
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case 4: se_dword += 1; break;
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case 8: se_multi += 1; break; /* ??? */
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}
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ret = -EFAULT;
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switch (instruction>>12) {
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case 0: /* mov.[bwl] to/from memory via r0+rn */
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@ -530,6 +619,27 @@ asmlinkage void do_address_error(struct pt_regs *regs,
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local_irq_enable();
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se_user += 1;
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/* shout about userspace fixups */
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if (se_usermode & 1)
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printk(KERN_NOTICE "Unaligned userspace access "
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"in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
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current->comm, current->pid, (void *)regs->pc,
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instruction);
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if (se_usermode & 2)
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goto fixup;
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if (se_usermode & 4)
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goto uspace_segv;
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else {
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/* ignore */
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trace_mark(kernel_arch_trap_exit, MARK_NOARGS);
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return;
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}
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fixup:
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/* bad PC is not something we can fix */
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if (regs->pc & 1) {
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si_code = BUS_ADRALN;
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@ -563,6 +673,14 @@ uspace_segv:
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info.si_addr = (void __user *)address;
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force_sig_info(SIGBUS, &info, current);
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} else {
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se_sys += 1;
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if (se_kernmode_warn)
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printk(KERN_NOTICE "Unaligned kernel access "
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"on behalf of \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
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current->comm, current->pid, (void *)regs->pc,
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instruction);
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if (regs->pc & 1)
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die("unaligned program counter", regs, error_code);
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@ -872,3 +990,38 @@ void dump_stack(void)
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show_stack(NULL, NULL);
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}
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EXPORT_SYMBOL(dump_stack);
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#ifdef CONFIG_PROC_FS
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/*
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* This needs to be done after sysctl_init, otherwise sys/ will be
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* overwritten. Actually, this shouldn't be in sys/ at all since
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* it isn't a sysctl, and it doesn't contain sysctl information.
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* We now locate it in /proc/cpu/alignment instead.
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*/
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static int __init alignment_init(void)
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{
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struct proc_dir_entry *dir, *res;
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dir = proc_mkdir("cpu", NULL);
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if (!dir)
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return -ENOMEM;
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res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, dir);
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if (!res)
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return -ENOMEM;
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res->read_proc = proc_alignment_read;
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res->write_proc = proc_alignment_write;
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res = create_proc_entry("kernel_alignment", S_IWUSR | S_IRUGO, dir);
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if (!res)
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return -ENOMEM;
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res->read_proc = proc_alignment_read;
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res->write_proc = proc_alignment_kern_write;
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return 0;
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}
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fs_initcall(alignment_init);
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#endif
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