cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ptrace.c (9217B)


      1// SPDX-License-Identifier: GPL-2.0
      2/* ptrace.c */
      3/* By Ross Biro 1/23/92 */
      4/* edited by Linus Torvalds */
      5/* mangled further by Bob Manson (manson@santafe.edu) */
      6/* more mutilation by David Mosberger (davidm@azstarnet.com) */
      7
      8#include <linux/kernel.h>
      9#include <linux/sched.h>
     10#include <linux/sched/task_stack.h>
     11#include <linux/mm.h>
     12#include <linux/smp.h>
     13#include <linux/errno.h>
     14#include <linux/ptrace.h>
     15#include <linux/user.h>
     16#include <linux/security.h>
     17#include <linux/signal.h>
     18#include <linux/audit.h>
     19
     20#include <linux/uaccess.h>
     21#include <asm/fpu.h>
     22
     23#include "proto.h"
     24
     25#define DEBUG	DBG_MEM
     26#undef DEBUG
     27
     28#ifdef DEBUG
     29enum {
     30	DBG_MEM		= (1<<0),
     31	DBG_BPT		= (1<<1),
     32	DBG_MEM_ALL	= (1<<2)
     33};
     34#define DBG(fac,args)	{if ((fac) & DEBUG) printk args;}
     35#else
     36#define DBG(fac,args)
     37#endif
     38
     39#define BREAKINST	0x00000080	/* call_pal bpt */
     40
     41/*
     42 * does not yet catch signals sent when the child dies.
     43 * in exit.c or in signal.c.
     44 */
     45
     46/*
     47 * Processes always block with the following stack-layout:
     48 *
     49 *  +================================+ <---- task + 2*PAGE_SIZE
     50 *  | PALcode saved frame (ps, pc,   | ^
     51 *  | gp, a0, a1, a2)		     | |
     52 *  +================================+ | struct pt_regs
     53 *  |	        		     | |
     54 *  | frame generated by SAVE_ALL    | |
     55 *  |	        		     | v
     56 *  +================================+
     57 *  |	        		     | ^
     58 *  | frame saved by do_switch_stack | | struct switch_stack
     59 *  |	        		     | v
     60 *  +================================+
     61 */
     62
     63/* 
     64 * The following table maps a register index into the stack offset at
     65 * which the register is saved.  Register indices are 0-31 for integer
     66 * regs, 32-63 for fp regs, and 64 for the pc.  Notice that sp and
     67 * zero have no stack-slot and need to be treated specially (see
     68 * get_reg/put_reg below).
     69 */
     70enum {
     71	REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
     72};
     73
     74#define PT_REG(reg) \
     75  (PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))
     76
     77#define SW_REG(reg) \
     78 (PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
     79  + offsetof(struct switch_stack, reg))
     80
     81static int regoff[] = {
     82	PT_REG(	   r0), PT_REG(	   r1), PT_REG(	   r2), PT_REG(	  r3),
     83	PT_REG(	   r4), PT_REG(	   r5), PT_REG(	   r6), PT_REG(	  r7),
     84	PT_REG(	   r8), SW_REG(	   r9), SW_REG(	  r10), SW_REG(	 r11),
     85	SW_REG(	  r12), SW_REG(	  r13), SW_REG(	  r14), SW_REG(	 r15),
     86	PT_REG(	  r16), PT_REG(	  r17), PT_REG(	  r18), PT_REG(	 r19),
     87	PT_REG(	  r20), PT_REG(	  r21), PT_REG(	  r22), PT_REG(	 r23),
     88	PT_REG(	  r24), PT_REG(	  r25), PT_REG(	  r26), PT_REG(	 r27),
     89	PT_REG(	  r28), PT_REG(	   gp),		   -1,		   -1,
     90	SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
     91	SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
     92	SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
     93	SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
     94	SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
     95	SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
     96	SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
     97	SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
     98	PT_REG(	   pc)
     99};
    100
    101static unsigned long zero;
    102
    103/*
    104 * Get address of register REGNO in task TASK.
    105 */
    106static unsigned long *
    107get_reg_addr(struct task_struct * task, unsigned long regno)
    108{
    109	unsigned long *addr;
    110
    111	if (regno == 30) {
    112		addr = &task_thread_info(task)->pcb.usp;
    113	} else if (regno == 65) {
    114		addr = &task_thread_info(task)->pcb.unique;
    115	} else if (regno == 31 || regno > 65) {
    116		zero = 0;
    117		addr = &zero;
    118	} else {
    119		addr = task_stack_page(task) + regoff[regno];
    120	}
    121	return addr;
    122}
    123
    124/*
    125 * Get contents of register REGNO in task TASK.
    126 */
    127static unsigned long
    128get_reg(struct task_struct * task, unsigned long regno)
    129{
    130	/* Special hack for fpcr -- combine hardware and software bits.  */
    131	if (regno == 63) {
    132		unsigned long fpcr = *get_reg_addr(task, regno);
    133		unsigned long swcr
    134		  = task_thread_info(task)->ieee_state & IEEE_SW_MASK;
    135		swcr = swcr_update_status(swcr, fpcr);
    136		return fpcr | swcr;
    137	}
    138	return *get_reg_addr(task, regno);
    139}
    140
    141/*
    142 * Write contents of register REGNO in task TASK.
    143 */
    144static int
    145put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
    146{
    147	if (regno == 63) {
    148		task_thread_info(task)->ieee_state
    149		  = ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
    150		     | (data & IEEE_SW_MASK));
    151		data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
    152	}
    153	*get_reg_addr(task, regno) = data;
    154	return 0;
    155}
    156
    157static inline int
    158read_int(struct task_struct *task, unsigned long addr, int * data)
    159{
    160	int copied = access_process_vm(task, addr, data, sizeof(int),
    161			FOLL_FORCE);
    162	return (copied == sizeof(int)) ? 0 : -EIO;
    163}
    164
    165static inline int
    166write_int(struct task_struct *task, unsigned long addr, int data)
    167{
    168	int copied = access_process_vm(task, addr, &data, sizeof(int),
    169			FOLL_FORCE | FOLL_WRITE);
    170	return (copied == sizeof(int)) ? 0 : -EIO;
    171}
    172
    173/*
    174 * Set breakpoint.
    175 */
    176int
    177ptrace_set_bpt(struct task_struct * child)
    178{
    179	int displ, i, res, reg_b, nsaved = 0;
    180	unsigned int insn, op_code;
    181	unsigned long pc;
    182
    183	pc  = get_reg(child, REG_PC);
    184	res = read_int(child, pc, (int *) &insn);
    185	if (res < 0)
    186		return res;
    187
    188	op_code = insn >> 26;
    189	if (op_code >= 0x30) {
    190		/*
    191		 * It's a branch: instead of trying to figure out
    192		 * whether the branch will be taken or not, we'll put
    193		 * a breakpoint at either location.  This is simpler,
    194		 * more reliable, and probably not a whole lot slower
    195		 * than the alternative approach of emulating the
    196		 * branch (emulation can be tricky for fp branches).
    197		 */
    198		displ = ((s32)(insn << 11)) >> 9;
    199		task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
    200		if (displ)		/* guard against unoptimized code */
    201			task_thread_info(child)->bpt_addr[nsaved++]
    202			  = pc + 4 + displ;
    203		DBG(DBG_BPT, ("execing branch\n"));
    204	} else if (op_code == 0x1a) {
    205		reg_b = (insn >> 16) & 0x1f;
    206		task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
    207		DBG(DBG_BPT, ("execing jump\n"));
    208	} else {
    209		task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
    210		DBG(DBG_BPT, ("execing normal insn\n"));
    211	}
    212
    213	/* install breakpoints: */
    214	for (i = 0; i < nsaved; ++i) {
    215		res = read_int(child, task_thread_info(child)->bpt_addr[i],
    216			       (int *) &insn);
    217		if (res < 0)
    218			return res;
    219		task_thread_info(child)->bpt_insn[i] = insn;
    220		DBG(DBG_BPT, ("    -> next_pc=%lx\n",
    221			      task_thread_info(child)->bpt_addr[i]));
    222		res = write_int(child, task_thread_info(child)->bpt_addr[i],
    223				BREAKINST);
    224		if (res < 0)
    225			return res;
    226	}
    227	task_thread_info(child)->bpt_nsaved = nsaved;
    228	return 0;
    229}
    230
    231/*
    232 * Ensure no single-step breakpoint is pending.  Returns non-zero
    233 * value if child was being single-stepped.
    234 */
    235int
    236ptrace_cancel_bpt(struct task_struct * child)
    237{
    238	int i, nsaved = task_thread_info(child)->bpt_nsaved;
    239
    240	task_thread_info(child)->bpt_nsaved = 0;
    241
    242	if (nsaved > 2) {
    243		printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
    244		nsaved = 2;
    245	}
    246
    247	for (i = 0; i < nsaved; ++i) {
    248		write_int(child, task_thread_info(child)->bpt_addr[i],
    249			  task_thread_info(child)->bpt_insn[i]);
    250	}
    251	return (nsaved != 0);
    252}
    253
    254void user_enable_single_step(struct task_struct *child)
    255{
    256	/* Mark single stepping.  */
    257	task_thread_info(child)->bpt_nsaved = -1;
    258}
    259
    260void user_disable_single_step(struct task_struct *child)
    261{
    262	ptrace_cancel_bpt(child);
    263}
    264
    265/*
    266 * Called by kernel/ptrace.c when detaching..
    267 *
    268 * Make sure the single step bit is not set.
    269 */
    270void ptrace_disable(struct task_struct *child)
    271{ 
    272	user_disable_single_step(child);
    273}
    274
    275long arch_ptrace(struct task_struct *child, long request,
    276		 unsigned long addr, unsigned long data)
    277{
    278	unsigned long tmp;
    279	size_t copied;
    280	long ret;
    281
    282	switch (request) {
    283	/* When I and D space are separate, these will need to be fixed.  */
    284	case PTRACE_PEEKTEXT: /* read word at location addr. */
    285	case PTRACE_PEEKDATA:
    286		copied = ptrace_access_vm(child, addr, &tmp, sizeof(tmp),
    287				FOLL_FORCE);
    288		ret = -EIO;
    289		if (copied != sizeof(tmp))
    290			break;
    291		
    292		force_successful_syscall_return();
    293		ret = tmp;
    294		break;
    295
    296	/* Read register number ADDR. */
    297	case PTRACE_PEEKUSR:
    298		force_successful_syscall_return();
    299		ret = get_reg(child, addr);
    300		DBG(DBG_MEM, ("peek $%lu->%#lx\n", addr, ret));
    301		break;
    302
    303	/* When I and D space are separate, this will have to be fixed.  */
    304	case PTRACE_POKETEXT: /* write the word at location addr. */
    305	case PTRACE_POKEDATA:
    306		ret = generic_ptrace_pokedata(child, addr, data);
    307		break;
    308
    309	case PTRACE_POKEUSR: /* write the specified register */
    310		DBG(DBG_MEM, ("poke $%lu<-%#lx\n", addr, data));
    311		ret = put_reg(child, addr, data);
    312		break;
    313	default:
    314		ret = ptrace_request(child, request, addr, data);
    315		break;
    316	}
    317	return ret;
    318}
    319
    320asmlinkage unsigned long syscall_trace_enter(void)
    321{
    322	unsigned long ret = 0;
    323	struct pt_regs *regs = current_pt_regs();
    324	if (test_thread_flag(TIF_SYSCALL_TRACE) &&
    325	    ptrace_report_syscall_entry(current_pt_regs()))
    326		ret = -1UL;
    327	audit_syscall_entry(regs->r0, regs->r16, regs->r17, regs->r18, regs->r19);
    328	return ret ?: current_pt_regs()->r0;
    329}
    330
    331asmlinkage void
    332syscall_trace_leave(void)
    333{
    334	audit_syscall_exit(current_pt_regs());
    335	if (test_thread_flag(TIF_SYSCALL_TRACE))
    336		ptrace_report_syscall_exit(current_pt_regs(), 0);
    337}