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96d4f267e4
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
377 lines
9.1 KiB
C
377 lines
9.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* unaligned.c: Unaligned load/store trap handling with special
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* cases for the kernel to do them more quickly.
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*
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* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
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* Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
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*/
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#include <linux/kernel.h>
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#include <linux/sched/signal.h>
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#include <linux/mm.h>
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#include <asm/ptrace.h>
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#include <asm/processor.h>
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#include <linux/uaccess.h>
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#include <linux/smp.h>
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#include <linux/perf_event.h>
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#include <asm/setup.h>
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#include "kernel.h"
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enum direction {
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load, /* ld, ldd, ldh, ldsh */
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store, /* st, std, sth, stsh */
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both, /* Swap, ldstub, etc. */
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fpload,
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fpstore,
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invalid,
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};
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static inline enum direction decode_direction(unsigned int insn)
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{
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unsigned long tmp = (insn >> 21) & 1;
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if(!tmp)
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return load;
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else {
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if(((insn>>19)&0x3f) == 15)
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return both;
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else
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return store;
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}
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}
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/* 8 = double-word, 4 = word, 2 = half-word */
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static inline int decode_access_size(unsigned int insn)
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{
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insn = (insn >> 19) & 3;
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if(!insn)
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return 4;
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else if(insn == 3)
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return 8;
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else if(insn == 2)
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return 2;
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else {
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printk("Impossible unaligned trap. insn=%08x\n", insn);
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die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
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return 4; /* just to keep gcc happy. */
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}
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}
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/* 0x400000 = signed, 0 = unsigned */
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static inline int decode_signedness(unsigned int insn)
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{
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return (insn & 0x400000);
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}
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static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
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unsigned int rd)
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{
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if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
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/* Wheee... */
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__asm__ __volatile__("save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"restore; restore; restore; restore;\n\t"
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"restore; restore; restore;\n\t");
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}
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}
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static inline int sign_extend_imm13(int imm)
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{
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return imm << 19 >> 19;
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}
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static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
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{
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struct reg_window32 *win;
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if(reg < 16)
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return (!reg ? 0 : regs->u_regs[reg]);
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/* Ho hum, the slightly complicated case. */
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win = (struct reg_window32 *) regs->u_regs[UREG_FP];
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return win->locals[reg - 16]; /* yes, I know what this does... */
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}
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static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
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{
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struct reg_window32 __user *win;
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unsigned long ret;
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if (reg < 16)
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return (!reg ? 0 : regs->u_regs[reg]);
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/* Ho hum, the slightly complicated case. */
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win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];
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if ((unsigned long)win & 3)
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return -1;
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if (get_user(ret, &win->locals[reg - 16]))
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return -1;
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return ret;
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}
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static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
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{
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struct reg_window32 *win;
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if(reg < 16)
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return ®s->u_regs[reg];
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win = (struct reg_window32 *) regs->u_regs[UREG_FP];
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return &win->locals[reg - 16];
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}
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static unsigned long compute_effective_address(struct pt_regs *regs,
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unsigned int insn)
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{
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unsigned int rs1 = (insn >> 14) & 0x1f;
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unsigned int rs2 = insn & 0x1f;
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unsigned int rd = (insn >> 25) & 0x1f;
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if(insn & 0x2000) {
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maybe_flush_windows(rs1, 0, rd);
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return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
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} else {
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maybe_flush_windows(rs1, rs2, rd);
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return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
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}
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}
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unsigned long safe_compute_effective_address(struct pt_regs *regs,
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unsigned int insn)
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{
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unsigned int rs1 = (insn >> 14) & 0x1f;
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unsigned int rs2 = insn & 0x1f;
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unsigned int rd = (insn >> 25) & 0x1f;
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if(insn & 0x2000) {
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maybe_flush_windows(rs1, 0, rd);
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return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
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} else {
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maybe_flush_windows(rs1, rs2, rd);
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return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
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}
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}
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/* This is just to make gcc think panic does return... */
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static void unaligned_panic(char *str)
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{
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panic("%s", str);
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}
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/* una_asm.S */
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extern int do_int_load(unsigned long *dest_reg, int size,
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unsigned long *saddr, int is_signed);
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extern int __do_int_store(unsigned long *dst_addr, int size,
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unsigned long *src_val);
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static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
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struct pt_regs *regs)
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{
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unsigned long zero[2] = { 0, 0 };
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unsigned long *src_val;
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if (reg_num)
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src_val = fetch_reg_addr(reg_num, regs);
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else {
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src_val = &zero[0];
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if (size == 8)
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zero[1] = fetch_reg(1, regs);
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}
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return __do_int_store(dst_addr, size, src_val);
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}
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extern void smp_capture(void);
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extern void smp_release(void);
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static inline void advance(struct pt_regs *regs)
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{
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regs->pc = regs->npc;
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regs->npc += 4;
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}
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static inline int floating_point_load_or_store_p(unsigned int insn)
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{
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return (insn >> 24) & 1;
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}
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static inline int ok_for_kernel(unsigned int insn)
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{
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return !floating_point_load_or_store_p(insn);
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}
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static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
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{
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unsigned long g2 = regs->u_regs [UREG_G2];
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unsigned long fixup = search_extables_range(regs->pc, &g2);
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if (!fixup) {
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unsigned long address = compute_effective_address(regs, insn);
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if(address < PAGE_SIZE) {
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printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
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} else
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printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
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printk(KERN_ALERT " at virtual address %08lx\n",address);
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printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
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(current->mm ? current->mm->context :
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current->active_mm->context));
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printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
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(current->mm ? (unsigned long) current->mm->pgd :
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(unsigned long) current->active_mm->pgd));
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die_if_kernel("Oops", regs);
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/* Not reached */
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}
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regs->pc = fixup;
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regs->npc = regs->pc + 4;
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regs->u_regs [UREG_G2] = g2;
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}
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asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
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{
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enum direction dir = decode_direction(insn);
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int size = decode_access_size(insn);
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if(!ok_for_kernel(insn) || dir == both) {
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printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
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regs->pc);
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unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
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} else {
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unsigned long addr = compute_effective_address(regs, insn);
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int err;
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perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
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switch (dir) {
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case load:
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err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
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regs),
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size, (unsigned long *) addr,
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decode_signedness(insn));
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break;
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case store:
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err = do_int_store(((insn>>25)&0x1f), size,
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(unsigned long *) addr, regs);
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break;
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default:
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panic("Impossible kernel unaligned trap.");
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/* Not reached... */
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}
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if (err)
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kernel_mna_trap_fault(regs, insn);
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else
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advance(regs);
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}
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}
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static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
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enum direction dir)
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{
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unsigned int reg;
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int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
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if ((regs->pc | regs->npc) & 3)
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return 0;
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/* Must access_ok() in all the necessary places. */
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#define WINREG_ADDR(regnum) \
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((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
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reg = (insn >> 25) & 0x1f;
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if (reg >= 16) {
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if (!access_ok(WINREG_ADDR(reg - 16), size))
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return -EFAULT;
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}
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reg = (insn >> 14) & 0x1f;
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if (reg >= 16) {
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if (!access_ok(WINREG_ADDR(reg - 16), size))
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return -EFAULT;
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}
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if (!(insn & 0x2000)) {
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reg = (insn & 0x1f);
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if (reg >= 16) {
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if (!access_ok(WINREG_ADDR(reg - 16), size))
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return -EFAULT;
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}
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}
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#undef WINREG_ADDR
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return 0;
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}
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static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
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{
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send_sig_fault(SIGBUS, BUS_ADRALN,
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(void __user *)safe_compute_effective_address(regs, insn),
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0, current);
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}
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asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
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{
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enum direction dir;
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if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
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(((insn >> 30) & 3) != 3))
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goto kill_user;
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dir = decode_direction(insn);
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if(!ok_for_user(regs, insn, dir)) {
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goto kill_user;
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} else {
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int err, size = decode_access_size(insn);
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unsigned long addr;
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if(floating_point_load_or_store_p(insn)) {
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printk("User FPU load/store unaligned unsupported.\n");
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goto kill_user;
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}
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addr = compute_effective_address(regs, insn);
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perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
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switch(dir) {
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case load:
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err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
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regs),
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size, (unsigned long *) addr,
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decode_signedness(insn));
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break;
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case store:
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err = do_int_store(((insn>>25)&0x1f), size,
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(unsigned long *) addr, regs);
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break;
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case both:
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/*
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* This was supported in 2.4. However, we question
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* the value of SWAP instruction across word boundaries.
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*/
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printk("Unaligned SWAP unsupported.\n");
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err = -EFAULT;
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break;
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default:
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unaligned_panic("Impossible user unaligned trap.");
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goto out;
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}
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if (err)
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goto kill_user;
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else
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advance(regs);
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goto out;
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}
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kill_user:
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user_mna_trap_fault(regs, insn);
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out:
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;
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}
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