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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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ed79b86d8a
Commit 81e192d6ce
("parisc: convert to
generic compat_sys_ptrace") introduced a bug which segfaults the parisc
64bit kernel when stracing 32bit applications:
Kernel Fault: Code=15 regs=00000000bafa42b0 (Addr=00000001baf5ab57)
YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
PSW: 00001000000001101111111100001011 Tainted: G W
r00-03 000000ff0806ff0b 000000004068edc0 00000000401203f8 00000000fb3e2508
r04-07 0000000040686dc0 00000000baf5a800 fffffffffffffffc fffffffffb3e2508
r08-11 00000000baf5a800 000000000004b068 00000000000402b0 0000000000040d68
r12-15 0000000000042a9c 0000000000040a9c 0000000000040d60 0000000000042e9c
r16-19 000000000004b060 000000000004b058 0000000000042d9c ffffffffffffffff
r20-23 000000000800000b 0000000000000000 000000000800000b fffffffffb3e2508
r24-27 00000000fffffffc 0000000000000003 00000000fffffffc 0000000040686dc0
r28-31 00000001baf5a7ff 00000000bafa4280 00000000bafa42b0 00000000000001d7
sr00-03 0000000000fca000 0000000000000000 0000000000000000 0000000000fca000
sr04-07 0000000000000000 0000000000000000 0000000000000000 0000000000000000
IASQ: 0000000000000000 0000000000000000 IAOQ: 0000000040120400 0000000040120404
IIR: 4b9a06b0 ISR: 0000000000000000 IOR: 00000001baf5ab57
CPU: 0 CR30: 00000000bafa4000 CR31: 00000000d22344e0
ORIG_R28: 00000000fb3e2248
IAOQ[0]: compat_arch_ptrace+0xb8/0x160
IAOQ[1]: compat_arch_ptrace+0xbc/0x160
RP(r2): compat_arch_ptrace+0xb0/0x160
Backtrace:
[<00000000401612ac>] compat_sys_ptrace+0x15c/0x180
[<0000000040104ef8>] syscall_exit+0x0/0x14
The problem is that compat_arch_ptrace() enters with an addr value of
type compat_ulong_t and calls translate_usr_offset() to translate the
address offset into a struct pt_regs offset like this:
addr = translate_usr_offset(addr)
this means that any return value of translate_usr_offset() is stored
back as compat_ulong_t type into the addr variable.
But since translate_usr_offset() returns -1 for invalid offsets, addr
can now get the value 0xffffffff which then fails the next return-value
sanity check and thus the kernel tries to access invalid memory:
if (addr < 0)
break;
Fix this bug by modifying translate_usr_offset() to take and return
values of type compat_ulong_t, and by returning the value
"sizeof(struct pt_regs)" as an error indicator.
Additionally change the sanity check to check for return values
for >= sizeof(struct pt_regs).
This patch survived my compile and run-tests.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
285 lines
8.0 KiB
C
285 lines
8.0 KiB
C
/*
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* Kernel support for the ptrace() and syscall tracing interfaces.
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*
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* Copyright (C) 2000 Hewlett-Packard Co, Linuxcare Inc.
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* Copyright (C) 2000 Matthew Wilcox <matthew@wil.cx>
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* Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
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* Copyright (C) 2008 Helge Deller <deller@gmx.de>
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*/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/errno.h>
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#include <linux/ptrace.h>
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#include <linux/user.h>
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#include <linux/personality.h>
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#include <linux/security.h>
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#include <linux/compat.h>
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#include <linux/signal.h>
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#include <asm/uaccess.h>
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#include <asm/pgtable.h>
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#include <asm/system.h>
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#include <asm/processor.h>
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#include <asm/asm-offsets.h>
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/* PSW bits we allow the debugger to modify */
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#define USER_PSW_BITS (PSW_N | PSW_V | PSW_CB)
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/*
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* Called by kernel/ptrace.c when detaching..
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*
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* Make sure single step bits etc are not set.
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*/
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void ptrace_disable(struct task_struct *task)
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{
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task->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
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/* make sure the trap bits are not set */
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pa_psw(task)->r = 0;
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pa_psw(task)->t = 0;
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pa_psw(task)->h = 0;
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pa_psw(task)->l = 0;
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}
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/*
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* The following functions are called by ptrace_resume() when
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* enabling or disabling single/block tracing.
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*/
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void user_disable_single_step(struct task_struct *task)
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{
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ptrace_disable(task);
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}
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void user_enable_single_step(struct task_struct *task)
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{
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task->ptrace &= ~PT_BLOCKSTEP;
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task->ptrace |= PT_SINGLESTEP;
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if (pa_psw(task)->n) {
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struct siginfo si;
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/* Nullified, just crank over the queue. */
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task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1];
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task_regs(task)->iasq[0] = task_regs(task)->iasq[1];
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task_regs(task)->iaoq[1] = task_regs(task)->iaoq[0] + 4;
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pa_psw(task)->n = 0;
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pa_psw(task)->x = 0;
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pa_psw(task)->y = 0;
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pa_psw(task)->z = 0;
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pa_psw(task)->b = 0;
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ptrace_disable(task);
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/* Don't wake up the task, but let the
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parent know something happened. */
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si.si_code = TRAP_TRACE;
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si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3);
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si.si_signo = SIGTRAP;
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si.si_errno = 0;
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force_sig_info(SIGTRAP, &si, task);
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/* notify_parent(task, SIGCHLD); */
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return;
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}
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/* Enable recovery counter traps. The recovery counter
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* itself will be set to zero on a task switch. If the
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* task is suspended on a syscall then the syscall return
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* path will overwrite the recovery counter with a suitable
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* value such that it traps once back in user space. We
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* disable interrupts in the tasks PSW here also, to avoid
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* interrupts while the recovery counter is decrementing.
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*/
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pa_psw(task)->r = 1;
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pa_psw(task)->t = 0;
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pa_psw(task)->h = 0;
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pa_psw(task)->l = 0;
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}
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void user_enable_block_step(struct task_struct *task)
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{
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task->ptrace &= ~PT_SINGLESTEP;
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task->ptrace |= PT_BLOCKSTEP;
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/* Enable taken branch trap. */
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pa_psw(task)->r = 0;
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pa_psw(task)->t = 1;
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pa_psw(task)->h = 0;
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pa_psw(task)->l = 0;
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}
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long arch_ptrace(struct task_struct *child, long request, long addr, long data)
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{
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unsigned long tmp;
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long ret = -EIO;
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switch (request) {
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/* Read the word at location addr in the USER area. For ptraced
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processes, the kernel saves all regs on a syscall. */
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case PTRACE_PEEKUSR:
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if ((addr & (sizeof(long)-1)) ||
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(unsigned long) addr >= sizeof(struct pt_regs))
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break;
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tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
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ret = put_user(tmp, (unsigned long *) data);
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break;
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/* Write the word at location addr in the USER area. This will need
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to change when the kernel no longer saves all regs on a syscall.
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FIXME. There is a problem at the moment in that r3-r18 are only
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saved if the process is ptraced on syscall entry, and even then
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those values are overwritten by actual register values on syscall
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exit. */
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case PTRACE_POKEUSR:
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/* Some register values written here may be ignored in
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* entry.S:syscall_restore_rfi; e.g. iaoq is written with
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* r31/r31+4, and not with the values in pt_regs.
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*/
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if (addr == PT_PSW) {
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/* Allow writing to Nullify, Divide-step-correction,
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* and carry/borrow bits.
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* BEWARE, if you set N, and then single step, it won't
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* stop on the nullified instruction.
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*/
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data &= USER_PSW_BITS;
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task_regs(child)->gr[0] &= ~USER_PSW_BITS;
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task_regs(child)->gr[0] |= data;
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ret = 0;
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break;
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}
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if ((addr & (sizeof(long)-1)) ||
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(unsigned long) addr >= sizeof(struct pt_regs))
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break;
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if ((addr >= PT_GR1 && addr <= PT_GR31) ||
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addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
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(addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
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addr == PT_SAR) {
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*(unsigned long *) ((char *) task_regs(child) + addr) = data;
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ret = 0;
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}
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break;
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default:
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ret = ptrace_request(child, request, addr, data);
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break;
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}
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return ret;
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}
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#ifdef CONFIG_COMPAT
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/* This function is needed to translate 32 bit pt_regs offsets in to
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* 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel
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* will request offset 12 if it wants gr3, but the lower 32 bits of
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* the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
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* This code relies on a 32 bit pt_regs being comprised of 32 bit values
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* except for the fp registers which (a) are 64 bits, and (b) follow
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* the gr registers at the start of pt_regs. The 32 bit pt_regs should
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* be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
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* being 64 bit in both cases.
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*/
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static compat_ulong_t translate_usr_offset(compat_ulong_t offset)
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{
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if (offset < 0)
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return sizeof(struct pt_regs);
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else if (offset <= 32*4) /* gr[0..31] */
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return offset * 2 + 4;
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else if (offset <= 32*4+32*8) /* gr[0..31] + fr[0..31] */
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return offset + 32*4;
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else if (offset < sizeof(struct pt_regs)/2 + 32*4)
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return offset * 2 + 4 - 32*8;
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else
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return sizeof(struct pt_regs);
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}
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long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
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compat_ulong_t addr, compat_ulong_t data)
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{
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compat_uint_t tmp;
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long ret = -EIO;
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switch (request) {
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case PTRACE_PEEKUSR:
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if (addr & (sizeof(compat_uint_t)-1))
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break;
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addr = translate_usr_offset(addr);
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if (addr >= sizeof(struct pt_regs))
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break;
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tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr);
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ret = put_user(tmp, (compat_uint_t *) (unsigned long) data);
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break;
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/* Write the word at location addr in the USER area. This will need
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to change when the kernel no longer saves all regs on a syscall.
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FIXME. There is a problem at the moment in that r3-r18 are only
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saved if the process is ptraced on syscall entry, and even then
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those values are overwritten by actual register values on syscall
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exit. */
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case PTRACE_POKEUSR:
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/* Some register values written here may be ignored in
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* entry.S:syscall_restore_rfi; e.g. iaoq is written with
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* r31/r31+4, and not with the values in pt_regs.
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*/
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if (addr == PT_PSW) {
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/* Since PT_PSW==0, it is valid for 32 bit processes
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* under 64 bit kernels as well.
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*/
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ret = arch_ptrace(child, request, addr, data);
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} else {
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if (addr & (sizeof(compat_uint_t)-1))
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break;
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addr = translate_usr_offset(addr);
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if (addr >= sizeof(struct pt_regs))
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break;
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if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
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/* Special case, fp regs are 64 bits anyway */
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*(__u64 *) ((char *) task_regs(child) + addr) = data;
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ret = 0;
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}
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else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
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addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
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addr == PT_SAR+4) {
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/* Zero the top 32 bits */
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*(__u32 *) ((char *) task_regs(child) + addr - 4) = 0;
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*(__u32 *) ((char *) task_regs(child) + addr) = data;
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ret = 0;
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}
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}
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break;
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default:
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ret = compat_ptrace_request(child, request, addr, data);
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break;
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}
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return ret;
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}
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#endif
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void syscall_trace(void)
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{
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if (!test_thread_flag(TIF_SYSCALL_TRACE))
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return;
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if (!(current->ptrace & PT_PTRACED))
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return;
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ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
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? 0x80 : 0));
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/*
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* this isn't the same as continuing with a signal, but it will do
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* for normal use. strace only continues with a signal if the
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* stopping signal is not SIGTRAP. -brl
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*/
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if (current->exit_code) {
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send_sig(current->exit_code, current, 1);
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current->exit_code = 0;
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}
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}
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