[PATCH 1/2] arm64: mm: drop VM_FAULT_BADMAP/VM_FAULT_BADACCESS

Kefeng Wang
2024-04-07T08:12:41Z

If bad map or access, directly set si_code to SEGV_MAPRR or SEGV_ACCERR,
also set fault to 0 and goto error handling, which make us to drop the
arch's special vm fault reason.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
arch/arm64/mm/fault.c | 41 ++++++++++++++++++-----------------------
1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 405f9aa831bd..61a2acae0dca 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -500,9 +500,6 @@ static bool is_write_abort(unsigned long esr)
return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM);
}

-#define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000)
-#define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000)
-
static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
struct pt_regs *regs)
{
@@ -513,6 +510,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
unsigned int mm_flags = FAULT_FLAG_DEFAULT;
unsigned long addr = untagged_addr(far);
struct vm_area_struct *vma;
+ int si_code;

if (kprobe_page_fault(regs, esr))
return 0;
@@ -572,9 +570,10 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,

if (!(vma->vm_flags & vm_flags)) {
vma_end_read(vma);
- fault = VM_FAULT_BADACCESS;
+ fault = 0;
+ si_code = SEGV_ACCERR;
count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
- goto done;
+ goto bad_area;
}
fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs);
if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
@@ -599,15 +598,18 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
retry:
vma = lock_mm_and_find_vma(mm, addr, regs);
if (unlikely(!vma)) {
- fault = VM_FAULT_BADMAP;
- goto done;
+ fault = 0;
+ si_code = SEGV_MAPERR;
+ goto bad_area;
}

- if (!(vma->vm_flags & vm_flags))
- fault = VM_FAULT_BADACCESS;
- else
- fault = handle_mm_fault(vma, addr, mm_flags, regs);
+ if (!(vma->vm_flags & vm_flags)) {
+ fault = 0;
+ si_code = SEGV_ACCERR;
+ goto bad_area;
+ }

+ fault = handle_mm_fault(vma, addr, mm_flags, regs);
/* Quick path to respond to signals */
if (fault_signal_pending(fault, regs)) {
if (!user_mode(regs))
@@ -626,13 +628,11 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
mmap_read_unlock(mm);

done:
- /*
- * Handle the "normal" (no error) case first.
- */
- if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
- VM_FAULT_BADACCESS))))
+ /* Handle the "normal" (no error) case first. */
+ if (likely(!(fault & VM_FAULT_ERROR)))
return 0;

+bad_area:
/*
* If we are in kernel mode at this point, we have no context to
* handle this fault with.
@@ -667,13 +667,8 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,

arm64_force_sig_mceerr(BUS_MCEERR_AR, far, lsb, inf->name);
} else {
- /*
- * Something tried to access memory that isn't in our memory
- * map.
- */
- arm64_force_sig_fault(SIGSEGV,
- fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR,
- far, inf->name);
+ /* Something tried to access memory that out of memory map */
+ arm64_force_sig_fault(SIGSEGV, si_code, far, inf->name);
}

return 0;
--
2.27.0