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Merge tag 'arc-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

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Pull ARC updates from Vineet Gupta:

 - long due rewrite of do_page_fault

 - refactoring of entry/exit code to utilize the double load/store
   instructions

 - hsdk platform updates

* tag 'arc-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: [plat-hsdk]: Enable AXI DW DMAC in defconfig
  ARC: [plat-hsdk]: enable DW SPI controller
  ARC: hide unused function unw_hdr_alloc
  ARC: [haps] Add Virtio support
  ARCv2: entry: simplify return to Delay Slot via interrupt
  ARC: entry: EV_Trap expects r10 (vs. r9) to have exception cause
  ARCv2: entry: rewrite to enable use of double load/stores LDD/STD
  ARCv2: entry: avoid a branch
  ARCv2: entry: push out the Z flag unclobber from common EXCEPTION_PROLOGUE
  ARCv2: entry: comments about hardware auto-save on taken interrupts
  ARC: mm: do_page_fault refactor #8: release mmap_sem sooner
  ARC: mm: do_page_fault refactor #7: fold the various error handling
  ARC: mm: do_page_fault refactor #6: error handlers to use same pattern
  ARC: mm: do_page_fault refactor #5: scoot no_context to end
  ARC: mm: do_page_fault refactor #4: consolidate retry related logic
  ARC: mm: do_page_fault refactor #3: tidyup vma access permission code
  ARC: mm: do_page_fault refactor #2: remove short lived variable
  ARC: mm: do_page_fault refactor #1: remove label @good_area
This commit is contained in:
Linus Torvalds
2019-07-16 15:07:51 -07:00
parent c309b6f242 24a20b0a44
commit 3eb514866f
14 changed files with 386 additions and 349 deletions
Download Patch File Download Diff File Expand all files Collapse all files

191
arch/arc/mm/fault.c
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@@ -63,24 +63,19 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
struct vm_area_struct *vma = NULL;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
int si_code = SEGV_MAPERR;
int ret;
vm_fault_t fault;
int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
int sig, si_code = SEGV_MAPERR;
unsigned int write = 0, exec = 0, mask;
vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
unsigned int flags; /* handle_mm_fault() input */
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*/
if (address >= VMALLOC_START && !user_mode(regs)) {
ret = handle_kernel_vaddr_fault(address);
if (unlikely(ret))
if (unlikely(handle_kernel_vaddr_fault(address)))
goto no_context;
else
return;
@@ -93,143 +88,117 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
if (faulthandler_disabled() || !mm)
goto no_context;
if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */
write = 1;
else if ((regs->ecr_vec == ECR_V_PROTV) &&
(regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
exec = 1;
flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
if (write)
flags |= FAULT_FLAG_WRITE;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
si_code = SEGV_ACCERR;
/* Handle protection violation, execute on heap or stack */
if ((regs->ecr_vec == ECR_V_PROTV) &&
(regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
goto bad_area;
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
if (unlikely(address < vma->vm_start)) {
if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
goto bad_area;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
* vm_area is good, now check permissions for this memory access
*/
mask = VM_READ;
if (write)
mask = VM_WRITE;
if (exec)
mask = VM_EXEC;
if (!(vma->vm_flags & mask)) {
si_code = SEGV_ACCERR;
goto bad_area;
}
fault = handle_mm_fault(vma, address, flags);
if (fatal_signal_pending(current)) {
/*
* Fault retry nuances
*/
if (unlikely(fault & VM_FAULT_RETRY)) {
/*
* if fault retry, mmap_sem already relinquished by core mm
* so OK to return to user mode (with signal handled first)
* If fault needs to be retried, handle any pending signals
* first (by returning to user mode).
* mmap_sem already relinquished by core mm for RETRY case
*/
if (fault & VM_FAULT_RETRY) {
if (fatal_signal_pending(current)) {
if (!user_mode(regs))
goto no_context;
return;
}
}
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
if (likely(!(fault & VM_FAULT_ERROR))) {
/*
* retry state machine
*/
if (flags & FAULT_FLAG_ALLOW_RETRY) {
/* To avoid updating stats twice for retry case */
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
regs, address);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
regs, address);
}
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
goto retry;
}
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
goto retry;
}
/* Fault Handled Gracefully */
up_read(&mm->mmap_sem);
return;
}
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGSEGV)
goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
/* no man's land */
BUG();
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
tsk->thread.fault_address = address;
force_sig_fault(SIGSEGV, si_code, (void __user *)address);
return;
}
no_context:
/* Are we prepared to handle this kernel fault?
*
* (The kernel has valid exception-points in the source
* when it accesses user-memory. When it fails in one
* of those points, we find it in a table and do a jump
* to some fixup code that loads an appropriate error
* code)
/*
* Major/minor page fault accounting
* (in case of retry we only land here once)
*/
if (fixup_exception(regs))
return;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
die("Oops", regs, address);
if (likely(!(fault & VM_FAULT_ERROR))) {
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
regs, address);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
regs, address);
}
out_of_memory:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
pagefault_out_of_memory();
/* Normal return path: fault Handled Gracefully */
return;
}
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
if (!user_mode(regs))
goto no_context;
if (fault & VM_FAULT_OOM) {
pagefault_out_of_memory();
return;
}
if (fault & VM_FAULT_SIGBUS) {
sig = SIGBUS;
si_code = BUS_ADRERR;
}
else {
sig = SIGSEGV;
}
tsk->thread.fault_address = address;
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
force_sig_fault(sig, si_code, (void __user *)address);
return;
no_context:
if (fixup_exception(regs))
return;
die("Oops", regs, address);
}