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Fix comment about unpriviledged instructions. Now, it matches with

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current state after r289372.

While here, do some style and comment cleanups.  No functional changes.

Approved by:	kib (mentor)
This commit is contained in:
skra 2015-11-04 15:35:22 +00:00
parent 14dab036a2
commit b59e6c253a
2 changed files with 36 additions and 35 deletions
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69
sys/arm/arm/trap-v6.c
View File

@ -98,18 +98,18 @@ struct abort {
* - Always fatal as we do not know what does it mean.
* Imprecise External Abort:
* - Always fatal, but can be handled somehow in the future.
* Now, due to PCIe buggy harware, ignored.
* Now, due to PCIe buggy hardware, ignored.
* Precise External Abort:
* - Always fatal, but who knows in the future???
* Debug Event:
* - Special handling.
* External Translation Abort (L1 & L2)
* - Always fatal as something is screwed up in page tables or harware.
* - Always fatal as something is screwed up in page tables or hardware.
* Domain Fault (L1 & L2):
* - Always fatal as we do not play game with domains.
* Alignment Fault:
* - Everything should be aligned in kernel including user to kernel and
* vice versa data copying, so we ignore pcb_onfault, and it's always fatal.
* - Everything should be aligned in kernel with exception of user to kernel
* and vice versa data copying, so if pcb_onfault is not set, it's fatal.
* We generate signal in case of abort from user mode.
* Instruction cache maintenance:
* - According to manual, this is translation fault during cache maintenance
@ -125,7 +125,7 @@ struct abort {
* Translation Fault (L1 & L2):
* - Standard fault mechanism is held including vm_fault().
* Permission Fault (L1 & L2):
* - Fast harware emulation of modify bits and in other cases, standard
* - Fast hardware emulation of modify bits and in other cases, standard
* fault mechanism is held including vm_fault().
*/
@ -167,7 +167,6 @@ static const struct abort aborts[] = {
{abort_fatal, "Undefined Code (0x40F)"}
};
static __inline void
call_trapsignal(struct thread *td, int sig, int code, vm_offset_t addr)
{
@ -195,7 +194,7 @@ call_trapsignal(struct thread *td, int sig, int code, vm_offset_t addr)
*
* The imprecise means that we don't know where the abort happened,
* thus FAR is undefined. The abort should not never fire, but hot
* plugging or accidental harware failure can be the cause of it.
* plugging or accidental hardware failure can be the cause of it.
* If the abort happens, it can even be on different (thread) context.
* Without any additional support, the abort is fatal, as we do not
* know what really happened.
@ -214,7 +213,9 @@ call_trapsignal(struct thread *td, int sig, int code, vm_offset_t addr)
static __inline void
abort_imprecise(struct trapframe *tf, u_int fsr, u_int prefetch, u_int usermode)
{
/* XXXX We can got imprecise abort as result of access
/*
* XXX - We can got imprecise abort as result of access
* to not-present PCI/PCIe configuration space.
*/
#if 0
@ -245,6 +246,7 @@ static __inline void
abort_debug(struct trapframe *tf, u_int fsr, u_int prefetch, u_int usermode,
u_int far)
{
if (usermode) {
struct thread *td;
@ -316,6 +318,18 @@ abort_handler(struct trapframe *tf, int prefetch)
return;
}
/*
* ARM has a set of unprivileged load and store instructions
* (LDRT/LDRBT/STRT/STRBT ...) which are supposed to be used in other
* than user mode and OS should recognize their aborts and behave
* appropriately. However, there is no way how to do that reasonably
* in general unless we restrict the handling somehow.
*
* For now, these instructions are used only in copyin()/copyout()
* like functions where usermode buffers are checked in advance that
* they are not from KVA space. Thus, no action is needed here.
*/
#ifdef ARM_NEW_PMAP
rv = pmap_fault(PCPU_GET(curpmap), far, fsr, idx, usermode);
if (rv == 0) {
@ -330,7 +344,6 @@ abort_handler(struct trapframe *tf, int prefetch)
/*
* Now, when we handled imprecise and debug aborts, the rest of
* aborts should be really related to mapping.
*
*/
PCPU_INC(cnt.v_trap);
@ -417,7 +430,7 @@ abort_handler(struct trapframe *tf, int prefetch)
return;
}
/* Handle remaining I cache aborts. */
/* Handle remaining I-cache aborts. */
if (idx == FAULT_ICACHE) {
if (abort_icache(tf, idx, fsr, far, prefetch, td, &ksig))
goto do_trapsignal;
@ -434,7 +447,7 @@ abort_handler(struct trapframe *tf, int prefetch)
* the MMU.
*/
/* fusubailout is used by [fs]uswintr to avoid page faulting */
/* fusubailout is used by [fs]uswintr to avoid page faulting. */
pcb = td->td_pcb;
if (__predict_false(pcb->pcb_onfault == fusubailout)) {
tf->tf_r0 = EFAULT;
@ -442,19 +455,6 @@ abort_handler(struct trapframe *tf, int prefetch)
return;
}
/*
* QQQ: ARM has a set of unprivileged load and store instructions
* (LDRT/LDRBT/STRT/STRBT ...) which are supposed to be used
* in other than user mode and OS should recognize their
* aborts and behaved appropriately. However, there is no way
* how to do that reasonably in general unless we restrict
* the handling somehow. One way is to limit the handling for
* aborts which come from undefined mode only.
*
* Anyhow, we do not use these instructions and do not implement
* any special handling for them.
*/
va = trunc_page(far);
if (va >= KERNBASE) {
/*
@ -536,7 +536,7 @@ out:
/*
* abort_fatal() handles the following data aborts:
*
* FAULT_DEBUG - Debug Event
* FAULT_ACCESS_xx - Acces Bit
* FAULT_EA_PREC - Precise External Abort
@ -553,8 +553,8 @@ out:
* Note: If 'l' is NULL, we assume we're dealing with a prefetch abort.
*/
static int
abort_fatal(struct trapframe *tf, u_int idx, u_int fsr, u_int far, u_int prefetch,
struct thread *td, struct ksig *ksig)
abort_fatal(struct trapframe *tf, u_int idx, u_int fsr, u_int far,
u_int prefetch, struct thread *td, struct ksig *ksig)
{
u_int usermode;
const char *mode;
@ -609,13 +609,13 @@ abort_fatal(struct trapframe *tf, u_int idx, u_int fsr, u_int far, u_int prefetc
*
* FAULT_ALIGN - Alignment fault
*
* Every memory access should be correctly aligned in kernel including
* user to kernel and vice versa data copying, so we ignore pcb_onfault,
* and it's always fatal. We generate a signal in case of abort from user mode.
* Everything should be aligned in kernel with exception of user to kernel
* and vice versa data copying, so if pcb_onfault is not set, it's fatal.
* We generate signal in case of abort from user mode.
*/
static int
abort_align(struct trapframe *tf, u_int idx, u_int fsr, u_int far, u_int prefetch,
struct thread *td, struct ksig *ksig)
abort_align(struct trapframe *tf, u_int idx, u_int fsr, u_int far,
u_int prefetch, struct thread *td, struct ksig *ksig)
{
u_int usermode;
@ -660,9 +660,10 @@ abort_align(struct trapframe *tf, u_int idx, u_int fsr, u_int far, u_int prefetc
* should be held here including vm_fault() calling.
*/
static int
abort_icache(struct trapframe *tf, u_int idx, u_int fsr, u_int far, u_int prefetch,
struct thread *td, struct ksig *ksig)
abort_icache(struct trapframe *tf, u_int idx, u_int fsr, u_int far,
u_int prefetch, struct thread *td, struct ksig *ksig)
{
abort_fatal(tf, idx, fsr, far, prefetch, td, ksig);
return(0);
}

2
sys/arm/include/armreg.h
View File

@ -403,7 +403,7 @@
#define FAULT_PERM_L1 0x00D /* Permission Fault (L1) */
#define FAULT_EA_TRAN_L2 0x00E /* External Translation Abort (L2) */
#define FAULT_PERM_L2 0x00F /* Permission Fault (L2) */
#define FAULT_TLB_CONFLICT 0x010 /* Permission Fault (L2) */
#define FAULT_TLB_CONFLICT 0x010 /* TLB Conflict Abort */
#define FAULT_EA_IMPREC 0x016 /* Asynchronous External Abort */
#define FAULT_PE_IMPREC 0x018 /* Asynchronous Parity Error */
#define FAULT_PARITY 0x019 /* Parity Error */