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Add x86 PT_GETFSBASE, PT_GETGSBASE machine-depended ptrace requests to

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obtain the thread %fs and %gs bases.  Add x86 PT_SETFSBASE and
PT_SETGSBASE requests to set the bases from debuggers.  The set
requests, similarly to the sysarch({I386,AMD64}_SET_FSBASE),
override the corresponding segment registers.

The main purpose of the operations is to retrieve and modify the tcb
address for debuggee.

Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2015-06-29 07:07:24 +00:00
parent 06d058bd23
commit 1817023775
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=284919
3 changed files with 117 additions and 2 deletions
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62
sys/amd64/amd64/ptrace_machdep.c
View File

@ -36,8 +36,12 @@ __FBSDID("$FreeBSD$");
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/sysent.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/frame.h>
#include <machine/vmparam.h>
static int
cpu_ptrace_xstate(struct thread *td, int req, void *addr, int data)
@ -110,6 +114,20 @@ cpu_ptrace_xstate(struct thread *td, int req, void *addr, int data)
return (error);
}
static void
cpu_ptrace_setbase(struct thread *td, int req, register_t r)
{
if (req == PT_SETFSBASE) {
td->td_pcb->pcb_fsbase = r;
td->td_frame->tf_fs = _ufssel;
} else {
td->td_pcb->pcb_gsbase = r;
td->td_frame->tf_gs = _ugssel;
}
set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
}
#ifdef COMPAT_FREEBSD32
#define PT_I386_GETXMMREGS (PT_FIRSTMACH + 0)
#define PT_I386_SETXMMREGS (PT_FIRSTMACH + 1)
@ -118,6 +136,7 @@ static int
cpu32_ptrace(struct thread *td, int req, void *addr, int data)
{
struct savefpu *fpstate;
uint32_t r;
int error;
switch (req) {
@ -142,6 +161,29 @@ cpu32_ptrace(struct thread *td, int req, void *addr, int data)
error = cpu_ptrace_xstate(td, req, addr, data);
break;
case PT_GETFSBASE:
case PT_GETGSBASE:
if (!SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
error = EINVAL;
break;
}
r = req == PT_GETFSBASE ? td->td_pcb->pcb_fsbase :
td->td_pcb->pcb_gsbase;
error = copyout(&r, addr, sizeof(r));
break;
case PT_SETFSBASE:
case PT_SETGSBASE:
if (!SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
error = EINVAL;
break;
}
error = copyin(addr, &r, sizeof(r));
if (error != 0)
break;
cpu_ptrace_setbase(td, req, r);
break;
default:
error = EINVAL;
break;
@ -154,6 +196,7 @@ cpu32_ptrace(struct thread *td, int req, void *addr, int data)
int
cpu_ptrace(struct thread *td, int req, void *addr, int data)
{
register_t *r, rv;
int error;
#ifdef COMPAT_FREEBSD32
@ -176,6 +219,25 @@ cpu_ptrace(struct thread *td, int req, void *addr, int data)
error = cpu_ptrace_xstate(td, req, addr, data);
break;
case PT_GETFSBASE:
case PT_GETGSBASE:
r = req == PT_GETFSBASE ? &td->td_pcb->pcb_fsbase :
&td->td_pcb->pcb_gsbase;
error = copyout(r, addr, sizeof(*r));
break;
case PT_SETFSBASE:
case PT_SETGSBASE:
error = copyin(addr, &rv, sizeof(rv));
if (error != 0)
break;
if (rv >= VM_MAXUSER_ADDRESS) {
error = EINVAL;
break;
}
cpu_ptrace_setbase(td, req, rv);
break;
default:
error = EINVAL;
break;

53
sys/i386/i386/ptrace_machdep.c
View File

@ -35,6 +35,7 @@ __FBSDID("$FreeBSD$");
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <machine/frame.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
@ -115,8 +116,8 @@ cpu_ptrace_xstate(struct thread *td, int req, void *addr, int data)
}
#endif
int
cpu_ptrace(struct thread *td, int req, void *addr, int data)
static int
cpu_ptrace_xmm(struct thread *td, int req, void *addr, int data)
{
#ifdef CPU_ENABLE_SSE
struct savexmm *fpstate;
@ -155,3 +156,51 @@ cpu_ptrace(struct thread *td, int req, void *addr, int data)
return (EINVAL);
#endif
}
int
cpu_ptrace(struct thread *td, int req, void *addr, int data)
{
struct segment_descriptor *sdp, sd;
register_t r;
int error;
switch (req) {
case PT_GETXMMREGS:
case PT_SETXMMREGS:
case PT_GETXSTATE_OLD:
case PT_SETXSTATE_OLD:
case PT_GETXSTATE_INFO:
case PT_GETXSTATE:
case PT_SETXSTATE:
error = cpu_ptrace_xmm(td, req, addr, data);
break;
case PT_GETFSBASE:
case PT_GETGSBASE:
sdp = req == PT_GETFSBASE ? &td->td_pcb->pcb_fsd :
&td->td_pcb->pcb_gsd;
r = sdp->sd_hibase << 24 | sdp->sd_lobase;
error = copyout(&r, addr, sizeof(r));
break;
case PT_SETFSBASE:
case PT_SETGSBASE:
error = copyin(addr, &r, sizeof(r));
if (error != 0)
break;
fill_based_sd(&sd, r);
if (req == PT_SETFSBASE) {
td->td_pcb->pcb_fsd = sd;
td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
} else {
td->td_pcb->pcb_gsd = sd;
td->td_pcb->pcb_gs = GSEL(GUGS_SEL, SEL_UPL);
}
break;
default:
return (EINVAL);
}
return (error);
}

4
sys/x86/include/ptrace.h
View File

@ -51,6 +51,10 @@
#define PT_GETXSTATE_INFO (PT_FIRSTMACH + 4)
#define PT_GETXSTATE (PT_FIRSTMACH + 5)
#define PT_SETXSTATE (PT_FIRSTMACH + 6)
#define PT_GETFSBASE (PT_FIRSTMACH + 7)
#define PT_SETFSBASE (PT_FIRSTMACH + 8)
#define PT_GETGSBASE (PT_FIRSTMACH + 9)
#define PT_SETGSBASE (PT_FIRSTMACH + 10)
/* Argument structure for PT_GETXSTATE_INFO. */
struct ptrace_xstate_info {