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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v5 05/25] Introduce clear_user and clear_guest
On Fri, 20 Jan 2012, Stefano Stabellini wrote:
> On Thu, 19 Jan 2012, Jan Beulich wrote:
> > >>> On 19.01.12 at 17:46, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> > > As I wanted to use the clear_guest stuff you add here for some
> > > cleanup/latent bug fix in x86's paging code, I pulled this patch into
> > > my local tree. Unfortunately the ia64 bits don't build, as you omitted
> > > the #define-s at the top of the file you took the code from.
> >
> > Further, the file you put this in is one that shouldn't be modified. The
> > correct way is to simply pull in Linux'es clear_user.S (see below).
> >
>
> Yes, I think that you are correct.
Can I add your signed-off-by to this patch?
I have pulled your changes in and removed my changes to
xen/arch/ia64/linux/memcpy_mck.S.
---
Introduce clear_user and clear_guest
Introduce clear_user for x86 and ia64, shamelessly taken from Linux.
The x86 version is the 32 bit clear_user implementation.
Introduce clear_guest for x86 and ia64. The x86 implementation is based
on clear_user and a new clear_user_hvm function.
The ia64 implementation is actually in xencomm and it is based on
xencomm_copy_to_guest.
Changes in v6:
- pull Linux'es ia64 clear_user.S.
Changes in v3:
- introduce clear_guest.
Changes in v2:
- change d0 to be a long;
- cast addr to long.
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
diff --git a/xen/arch/ia64/linux/Makefile b/xen/arch/ia64/linux/Makefile
index 10ebbfc..6a3704b 100644
--- a/xen/arch/ia64/linux/Makefile
+++ b/xen/arch/ia64/linux/Makefile
@@ -4,6 +4,7 @@ subdir-y += sn
obj-y += bitop.o
obj-y += clear_page.o
+obj-y += clear_user.o
obj-y += copy_page_mck.o
obj-y += efi_stub.o
obj-y += extable.o
diff --git a/xen/arch/ia64/linux/README.origin
b/xen/arch/ia64/linux/README.origin
index 4dc96d3..3727fe5 100644
--- a/xen/arch/ia64/linux/README.origin
+++ b/xen/arch/ia64/linux/README.origin
@@ -15,6 +15,7 @@ pcdp.h -> linux/drivers/firmware/pcdp.h
bitop.c -> linux/arch/ia64/lib/bitop.c
clear_page.S -> linux/arch/ia64/lib/clear_page.S
+clear_user.S -> linux/arch/ia64/lib/clear_user.S
copy_page_mck.S -> linux/arch/ia64/lib/copy_page_mck.S
flush.S -> linux/arch/ia64/lib/flush.S
idiv32.S -> linux/arch/ia64/lib/idiv32.S
diff --git a/xen/arch/ia64/linux/clear_user.S b/xen/arch/ia64/linux/clear_user.S
new file mode 100644
index 0000000..eecd857
--- /dev/null
+++ b/xen/arch/ia64/linux/clear_user.S
@@ -0,0 +1,209 @@
+/*
+ * This routine clears to zero a linear memory buffer in user space.
+ *
+ * Inputs:
+ * in0: address of buffer
+ * in1: length of buffer in bytes
+ * Outputs:
+ * r8: number of bytes that didn't get cleared due to a fault
+ *
+ * Copyright (C) 1998, 1999, 2001 Hewlett-Packard Co
+ * Stephane Eranian <eranian@xxxxxxxxxx>
+ */
+
+#include <asm/asmmacro.h>
+
+//
+// arguments
+//
+#define buf r32
+#define len r33
+
+//
+// local registers
+//
+#define cnt r16
+#define buf2 r17
+#define saved_lc r18
+#define saved_pfs r19
+#define tmp r20
+#define len2 r21
+#define len3 r22
+
+//
+// Theory of operations:
+// - we check whether or not the buffer is small, i.e., less than 17
+// in which case we do the byte by byte loop.
+//
+// - Otherwise we go progressively from 1 byte store to 8byte store in
+// the head part, the body is a 16byte store loop and we finish we the
+// tail for the last 15 bytes.
+// The good point about this breakdown is that the long buffer handling
+// contains only 2 branches.
+//
+// The reason for not using shifting & masking for both the head and the
+// tail is to stay semantically correct. This routine is not supposed
+// to write bytes outside of the buffer. While most of the time this would
+// be ok, we can't tolerate a mistake. A classical example is the case
+// of multithreaded code were to the extra bytes touched is actually owned
+// by another thread which runs concurrently to ours. Another, less likely,
+// example is with device drivers where reading an I/O mapped location may
+// have side effects (same thing for writing).
+//
+
+GLOBAL_ENTRY(__do_clear_user)
+ .prologue
+ .save ar.pfs, saved_pfs
+ alloc saved_pfs=ar.pfs,2,0,0,0
+ cmp.eq p6,p0=r0,len // check for zero length
+ .save ar.lc, saved_lc
+ mov saved_lc=ar.lc // preserve ar.lc (slow)
+ .body
+ ;; // avoid WAW on CFM
+ adds tmp=-1,len // br.ctop is repeat/until
+ mov ret0=len // return value is length at this point
+(p6) br.ret.spnt.many rp
+ ;;
+ cmp.lt p6,p0=16,len // if len > 16 then long memset
+ mov ar.lc=tmp // initialize lc for small count
+(p6) br.cond.dptk .long_do_clear
+ ;; // WAR on ar.lc
+ //
+ // worst case 16 iterations, avg 8 iterations
+ //
+ // We could have played with the predicates to use the extra
+ // M slot for 2 stores/iteration but the cost the initialization
+ // the various counters compared to how long the loop is supposed
+ // to last on average does not make this solution viable.
+ //
+1:
+ EX( .Lexit1, st1 [buf]=r0,1 )
+ adds len=-1,len // countdown length using len
+ br.cloop.dptk 1b
+ ;; // avoid RAW on ar.lc
+ //
+ // .Lexit4: comes from byte by byte loop
+ // len contains bytes left
+.Lexit1:
+ mov ret0=len // faster than using ar.lc
+ mov ar.lc=saved_lc
+ br.ret.sptk.many rp // end of short clear_user
+
+
+ //
+ // At this point we know we have more than 16 bytes to copy
+ // so we focus on alignment (no branches required)
+ //
+ // The use of len/len2 for countdown of the number of bytes left
+ // instead of ret0 is due to the fact that the exception code
+ // changes the values of r8.
+ //
+.long_do_clear:
+ tbit.nz p6,p0=buf,0 // odd alignment (for long_do_clear)
+ ;;
+ EX( .Lexit3, (p6) st1 [buf]=r0,1 ) // 1-byte aligned
+(p6) adds len=-1,len;; // sync because buf is modified
+ tbit.nz p6,p0=buf,1
+ ;;
+ EX( .Lexit3, (p6) st2 [buf]=r0,2 ) // 2-byte aligned
+(p6) adds len=-2,len;;
+ tbit.nz p6,p0=buf,2
+ ;;
+ EX( .Lexit3, (p6) st4 [buf]=r0,4 ) // 4-byte aligned
+(p6) adds len=-4,len;;
+ tbit.nz p6,p0=buf,3
+ ;;
+ EX( .Lexit3, (p6) st8 [buf]=r0,8 ) // 8-byte aligned
+(p6) adds len=-8,len;;
+ shr.u cnt=len,4 // number of 128-bit (2x64bit) words
+ ;;
+ cmp.eq p6,p0=r0,cnt
+ adds tmp=-1,cnt
+(p6) br.cond.dpnt .dotail // we have less than 16 bytes left
+ ;;
+ adds buf2=8,buf // setup second base pointer
+ mov ar.lc=tmp
+ ;;
+
+ //
+ // 16bytes/iteration core loop
+ //
+ // The second store can never generate a fault because
+ // we come into the loop only when we are 16-byte aligned.
+ // This means that if we cross a page then it will always be
+ // in the first store and never in the second.
+ //
+ //
+ // We need to keep track of the remaining length. A possible
(optimistic)
+ // way would be to use ar.lc and derive how many byte were left by
+ // doing : left= 16*ar.lc + 16. this would avoid the addition at
+ // every iteration.
+ // However we need to keep the synchronization point. A template
+ // M;;MB does not exist and thus we can keep the addition at no
+ // extra cycle cost (use a nop slot anyway). It also simplifies the
+ // (unlikely) error recovery code
+ //
+
+2: EX(.Lexit3, st8 [buf]=r0,16 )
+ ;; // needed to get len correct when error
+ st8 [buf2]=r0,16
+ adds len=-16,len
+ br.cloop.dptk 2b
+ ;;
+ mov ar.lc=saved_lc
+ //
+ // tail correction based on len only
+ //
+ // We alternate the use of len3,len2 to allow parallelism and correct
+ // error handling. We also reuse p6/p7 to return correct value.
+ // The addition of len2/len3 does not cost anything more compared to
+ // the regular memset as we had empty slots.
+ //
+.dotail:
+ mov len2=len // for parallelization of error handling
+ mov len3=len
+ tbit.nz p6,p0=len,3
+ ;;
+ EX( .Lexit2, (p6) st8 [buf]=r0,8 ) // at least 8 bytes
+(p6) adds len3=-8,len2
+ tbit.nz p7,p6=len,2
+ ;;
+ EX( .Lexit2, (p7) st4 [buf]=r0,4 ) // at least 4 bytes
+(p7) adds len2=-4,len3
+ tbit.nz p6,p7=len,1
+ ;;
+ EX( .Lexit2, (p6) st2 [buf]=r0,2 ) // at least 2 bytes
+(p6) adds len3=-2,len2
+ tbit.nz p7,p6=len,0
+ ;;
+ EX( .Lexit2, (p7) st1 [buf]=r0 ) // only 1 byte left
+ mov ret0=r0 // success
+ br.ret.sptk.many rp // end of most likely path
+
+ //
+ // Outlined error handling code
+ //
+
+ //
+ // .Lexit3: comes from core loop, need restore pr/lc
+ // len contains bytes left
+ //
+ //
+ // .Lexit2:
+ // if p6 -> coming from st8 or st2 : len2 contains what's left
+ // if p7 -> coming from st4 or st1 : len3 contains what's left
+ // We must restore lc/pr even though might not have been used.
+.Lexit2:
+ .pred.rel "mutex", p6, p7
+(p6) mov len=len2
+(p7) mov len=len3
+ ;;
+ //
+ // .Lexit4: comes from head, need not restore pr/lc
+ // len contains bytes left
+ //
+.Lexit3:
+ mov ret0=len
+ mov ar.lc=saved_lc
+ br.ret.sptk.many rp
+END(__do_clear_user)
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 160a47f..de1a0ed 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2390,6 +2390,96 @@ static enum hvm_copy_result __hvm_copy(
return HVMCOPY_okay;
}
+static enum hvm_copy_result __hvm_clear(paddr_t addr, int size)
+{
+ struct vcpu *curr = current;
+ unsigned long gfn, mfn;
+ p2m_type_t p2mt;
+ char *p;
+ int count, todo = size;
+ uint32_t pfec = PFEC_page_present | PFEC_write_access;
+
+ /*
+ * XXX Disable for 4.1.0: PV-on-HVM drivers will do grant-table ops
+ * such as query_size. Grant-table code currently does copy_to/from_guest
+ * accesses under the big per-domain lock, which this test would disallow.
+ * The test is not needed until we implement sleeping-on-waitqueue when
+ * we access a paged-out frame, and that's post 4.1.0 now.
+ */
+#if 0
+ /*
+ * If the required guest memory is paged out, this function may sleep.
+ * Hence we bail immediately if called from atomic context.
+ */
+ if ( in_atomic() )
+ return HVMCOPY_unhandleable;
+#endif
+
+ while ( todo > 0 )
+ {
+ count = min_t(int, PAGE_SIZE - (addr & ~PAGE_MASK), todo);
+
+ gfn = paging_gva_to_gfn(curr, addr, &pfec);
+ if ( gfn == INVALID_GFN )
+ {
+ if ( pfec == PFEC_page_paged )
+ return HVMCOPY_gfn_paged_out;
+ if ( pfec == PFEC_page_shared )
+ return HVMCOPY_gfn_shared;
+ return HVMCOPY_bad_gva_to_gfn;
+ }
+
+ mfn = mfn_x(get_gfn_unshare(curr->domain, gfn, &p2mt));
+
+ if ( p2m_is_paging(p2mt) )
+ {
+ p2m_mem_paging_populate(curr->domain, gfn);
+ put_gfn(curr->domain, gfn);
+ return HVMCOPY_gfn_paged_out;
+ }
+ if ( p2m_is_shared(p2mt) )
+ {
+ put_gfn(curr->domain, gfn);
+ return HVMCOPY_gfn_shared;
+ }
+ if ( p2m_is_grant(p2mt) )
+ {
+ put_gfn(curr->domain, gfn);
+ return HVMCOPY_unhandleable;
+ }
+ if ( !p2m_is_ram(p2mt) )
+ {
+ put_gfn(curr->domain, gfn);
+ return HVMCOPY_bad_gfn_to_mfn;
+ }
+ ASSERT(mfn_valid(mfn));
+
+ p = (char *)map_domain_page(mfn) + (addr & ~PAGE_MASK);
+
+ if ( p2mt == p2m_ram_ro )
+ {
+ static unsigned long lastpage;
+ if ( xchg(&lastpage, gfn) != gfn )
+ gdprintk(XENLOG_DEBUG, "guest attempted write to read-only"
+ " memory page. gfn=%#lx, mfn=%#lx\n",
+ gfn, mfn);
+ }
+ else
+ {
+ memset(p, 0x00, count);
+ paging_mark_dirty(curr->domain, mfn);
+ }
+
+ unmap_domain_page(p);
+
+ addr += count;
+ todo -= count;
+ put_gfn(curr->domain, gfn);
+ }
+
+ return HVMCOPY_okay;
+}
+
enum hvm_copy_result hvm_copy_to_guest_phys(
paddr_t paddr, void *buf, int size)
{
@@ -2476,6 +2566,23 @@ unsigned long copy_to_user_hvm(void *to, const void
*from, unsigned int len)
return rc ? len : 0; /* fake a copy_to_user() return code */
}
+unsigned long clear_user_hvm(void *to, unsigned int len)
+{
+ int rc;
+
+#ifdef __x86_64__
+ if ( !current->arch.hvm_vcpu.hcall_64bit &&
+ is_compat_arg_xlat_range(to, len) )
+ {
+ memset(to, 0x00, len);
+ return 0;
+ }
+#endif
+
+ rc = __hvm_clear((unsigned long)to, len);
+ return rc ? len : 0; /* fake a copy_to_user() return code */
+}
+
unsigned long copy_from_user_hvm(void *to, const void *from, unsigned len)
{
int rc;
diff --git a/xen/arch/x86/usercopy.c b/xen/arch/x86/usercopy.c
index d88e635..47dadae 100644
--- a/xen/arch/x86/usercopy.c
+++ b/xen/arch/x86/usercopy.c
@@ -110,6 +110,42 @@ copy_to_user(void __user *to, const void *from, unsigned n)
return n;
}
+#define __do_clear_user(addr,size) \
+do { \
+ long __d0; \
+ __asm__ __volatile__( \
+ "0: rep; stosl\n" \
+ " movl %2,%0\n" \
+ "1: rep; stosb\n" \
+ "2:\n" \
+ ".section .fixup,\"ax\"\n" \
+ "3: lea 0(%2,%0,4),%0\n" \
+ " jmp 2b\n" \
+ ".previous\n" \
+ _ASM_EXTABLE(0b,3b) \
+ _ASM_EXTABLE(1b,2b) \
+ : "=&c"(size), "=&D" (__d0) \
+ : "r"(size & 3), "0"(size / 4), "1"((long)addr), "a"(0));
\
+} while (0)
+
+/**
+ * clear_user: - Zero a block of memory in user space.
+ * @to: Destination address, in user space.
+ * @n: Number of bytes to zero.
+ *
+ * Zero a block of memory in user space.
+ *
+ * Returns number of bytes that could not be cleared.
+ * On success, this will be zero.
+ */
+unsigned long
+clear_user(void __user *to, unsigned n)
+{
+ if ( access_ok(to, n) )
+ __do_clear_user(to, n);
+ return n;
+}
+
/**
* copy_from_user: - Copy a block of data from user space.
* @to: Destination address, in kernel space.
diff --git a/xen/common/xencomm.c b/xen/common/xencomm.c
index 2475454..9f6c1c5 100644
--- a/xen/common/xencomm.c
+++ b/xen/common/xencomm.c
@@ -414,6 +414,117 @@ out:
return n - from_pos;
}
+static int
+xencomm_clear_chunk(
+ unsigned long paddr, unsigned int len)
+{
+ struct page_info *page;
+ int res;
+
+ do {
+ res = xencomm_get_page(paddr, &page);
+ } while ( res == -EAGAIN );
+
+ if ( res )
+ return res;
+
+ memset(xencomm_vaddr(paddr, page), 0x00, len);
+ xencomm_mark_dirty((unsigned long)xencomm_vaddr(paddr, page), len);
+ put_page(page);
+
+ return 0;
+}
+
+static unsigned long
+xencomm_inline_clear_guest(
+ void *to, unsigned int n, unsigned int skip)
+{
+ unsigned long dest_paddr = xencomm_inline_addr(to) + skip;
+
+ while ( n > 0 )
+ {
+ unsigned int chunksz, bytes;
+
+ chunksz = PAGE_SIZE - (dest_paddr % PAGE_SIZE);
+ bytes = min(chunksz, n);
+
+ if ( xencomm_clear_chunk(dest_paddr, bytes) )
+ return n;
+ dest_paddr += bytes;
+ n -= bytes;
+ }
+
+ /* Always successful. */
+ return 0;
+}
+
+/**
+ * xencomm_clear_guest: Clear a block of data in domain space.
+ * @to: Physical address to xencomm buffer descriptor.
+ * @n: Number of bytes to copy.
+ * @skip: Number of bytes from the start to skip.
+ *
+ * Clear domain data
+ *
+ * Returns number of bytes that could not be cleared
+ * On success, this will be zero.
+ */
+unsigned long
+xencomm_clear_guest(
+ void *to, unsigned int n, unsigned int skip)
+{
+ struct xencomm_ctxt ctxt;
+ unsigned int from_pos = 0;
+ unsigned int to_pos = 0;
+ unsigned int i = 0;
+
+ if ( xencomm_is_inline(to) )
+ return xencomm_inline_clear_guest(to, n, skip);
+
+ if ( xencomm_ctxt_init(to, &ctxt) )
+ return n;
+
+ /* Iterate through the descriptor, copying up to a page at a time */
+ while ( (from_pos < n) && (i < xencomm_ctxt_nr_addrs(&ctxt)) )
+ {
+ unsigned long dest_paddr;
+ unsigned int pgoffset, chunksz, chunk_skip;
+
+ if ( xencomm_ctxt_next(&ctxt, i) )
+ goto out;
+ dest_paddr = *xencomm_ctxt_address(&ctxt);
+ if ( dest_paddr == XENCOMM_INVALID )
+ {
+ i++;
+ continue;
+ }
+
+ pgoffset = dest_paddr % PAGE_SIZE;
+ chunksz = PAGE_SIZE - pgoffset;
+
+ chunk_skip = min(chunksz, skip);
+ to_pos += chunk_skip;
+ chunksz -= chunk_skip;
+ skip -= chunk_skip;
+
+ if ( skip == 0 && chunksz > 0 )
+ {
+ unsigned int bytes = min(chunksz, n - from_pos);
+
+ if ( xencomm_clear_chunk(dest_paddr + chunk_skip, bytes) )
+ goto out;
+ from_pos += bytes;
+ to_pos += bytes;
+ }
+
+ i++;
+ }
+
+out:
+ xencomm_ctxt_done(&ctxt);
+ return n - from_pos;
+}
+
static int xencomm_inline_add_offset(void **handle, unsigned int bytes)
{
*handle += bytes;
diff --git a/xen/include/asm-ia64/uaccess.h b/xen/include/asm-ia64/uaccess.h
index 32ef415..2ececb1 100644
--- a/xen/include/asm-ia64/uaccess.h
+++ b/xen/include/asm-ia64/uaccess.h
@@ -236,6 +236,18 @@ __copy_from_user (void *to, const void __user *from,
unsigned long count)
__cu_len;
\
})
+extern unsigned long __do_clear_user (void __user * to, unsigned long count);
+
+#define clear_user(to, n) \
+({ \
+ void __user *__cu_to = (to);
\
+ long __cu_len = (n);
\
+
\
+ if (__access_ok(__cu_to))
\
+ __cu_len = __do_clear_user(__cu_to, __cu_len); \
+ __cu_len; \
+})
+
#define copy_from_user(to, from, n)
\
({
\
void *__cu_to = (to);
\
diff --git a/xen/include/asm-x86/guest_access.h
b/xen/include/asm-x86/guest_access.h
index 99ea64d..2b429c2 100644
--- a/xen/include/asm-x86/guest_access.h
+++ b/xen/include/asm-x86/guest_access.h
@@ -21,6 +21,10 @@
(is_hvm_vcpu(current) ? \
copy_from_user_hvm((dst), (src), (len)) : \
copy_from_user((dst), (src), (len)))
+#define raw_clear_guest(dst, len) \
+ (is_hvm_vcpu(current) ? \
+ clear_user_hvm((dst), (len)) : \
+ clear_user((dst), (len)))
#define __raw_copy_to_guest(dst, src, len) \
(is_hvm_vcpu(current) ? \
copy_to_user_hvm((dst), (src), (len)) : \
@@ -29,6 +33,10 @@
(is_hvm_vcpu(current) ? \
copy_from_user_hvm((dst), (src), (len)) : \
__copy_from_user((dst), (src), (len)))
+#define __raw_clear_guest(dst, len) \
+ (is_hvm_vcpu(current) ? \
+ clear_user_hvm((dst), (len)) : \
+ clear_user((dst), (len)))
/* Is the guest handle a NULL reference? */
#define guest_handle_is_null(hnd) ((hnd).p == NULL)
@@ -69,6 +77,11 @@
raw_copy_from_guest(_d, _s+(off), sizeof(*_d)*(nr));\
})
+#define clear_guest_offset(hnd, off, nr) ({ \
+ void *_d = (hnd).p; \
+ raw_clear_guest(_d+(off), nr); \
+})
+
/* Copy sub-field of a structure to guest context via a guest handle. */
#define copy_field_to_guest(hnd, ptr, field) ({ \
const typeof(&(ptr)->field) _s = &(ptr)->field; \
@@ -110,6 +123,11 @@
__raw_copy_from_guest(_d, _s+(off), sizeof(*_d)*(nr));\
})
+#define __clear_guest_offset(hnd, off, nr) ({ \
+ void *_d = (hnd).p; \
+ __raw_clear_guest(_d+(off), nr); \
+})
+
#define __copy_field_to_guest(hnd, ptr, field) ({ \
const typeof(&(ptr)->field) _s = &(ptr)->field; \
void *_d = &(hnd).p->field; \
diff --git a/xen/include/asm-x86/hvm/guest_access.h
b/xen/include/asm-x86/hvm/guest_access.h
index 7a89e81..b92dbe9 100644
--- a/xen/include/asm-x86/hvm/guest_access.h
+++ b/xen/include/asm-x86/hvm/guest_access.h
@@ -2,6 +2,7 @@
#define __ASM_X86_HVM_GUEST_ACCESS_H__
unsigned long copy_to_user_hvm(void *to, const void *from, unsigned len);
+unsigned long clear_user_hvm(void *to, unsigned int len);
unsigned long copy_from_user_hvm(void *to, const void *from, unsigned len);
#endif /* __ASM_X86_HVM_GUEST_ACCESS_H__ */
diff --git a/xen/include/asm-x86/uaccess.h b/xen/include/asm-x86/uaccess.h
index e3e541b..d6f4458 100644
--- a/xen/include/asm-x86/uaccess.h
+++ b/xen/include/asm-x86/uaccess.h
@@ -16,6 +16,7 @@
#endif
unsigned long copy_to_user(void *to, const void *from, unsigned len);
+unsigned long clear_user(void *to, unsigned len);
unsigned long copy_from_user(void *to, const void *from, unsigned len);
/* Handles exceptions in both to and from, but doesn't do access_ok */
unsigned long __copy_to_user_ll(void *to, const void *from, unsigned n);
diff --git a/xen/include/xen/guest_access.h b/xen/include/xen/guest_access.h
index 0b9fb07..373454e 100644
--- a/xen/include/xen/guest_access.h
+++ b/xen/include/xen/guest_access.h
@@ -15,10 +15,16 @@
#define copy_from_guest(ptr, hnd, nr) \
copy_from_guest_offset(ptr, hnd, 0, nr)
+#define clear_guest(hnd, nr) \
+ clear_guest_offset(hnd, 0, nr)
+
#define __copy_to_guest(hnd, ptr, nr) \
__copy_to_guest_offset(hnd, 0, ptr, nr)
#define __copy_from_guest(ptr, hnd, nr) \
__copy_from_guest_offset(ptr, hnd, 0, nr)
+#define __clear_guest(hnd, nr) \
+ __clear_guest_offset(hnd, 0, nr)
+
#endif /* __XEN_GUEST_ACCESS_H__ */
diff --git a/xen/include/xen/xencomm.h b/xen/include/xen/xencomm.h
index bce2ca7..730da7c 100644
--- a/xen/include/xen/xencomm.h
+++ b/xen/include/xen/xencomm.h
@@ -27,6 +27,8 @@ unsigned long xencomm_copy_to_guest(
void *to, const void *from, unsigned int len, unsigned int skip);
unsigned long xencomm_copy_from_guest(
void *to, const void *from, unsigned int len, unsigned int skip);
+unsigned long xencomm_clear_guest(
+ void *to, unsigned int n, unsigned int skip);
int xencomm_add_offset(void **handle, unsigned int bytes);
int xencomm_handle_is_null(void *ptr);
@@ -41,6 +43,16 @@ static inline unsigned long xencomm_inline_addr(const void
*handle)
return (unsigned long)handle & ~XENCOMM_INLINE_FLAG;
}
+#define raw_copy_to_guest(dst, src, len) \
+ xencomm_copy_to_guest(dst, src, len, 0)
+#define raw_copy_from_guest(dst, src, len) \
+ xencomm_copy_from_guest(dst, src, nr, 0)
+#define raw_clear_guest(dst, len) \
+ xencomm_clear_guest(dst, len, 0)
+#define __raw_copy_to_guest raw_copy_to_guest
+#define __raw_copy_from_guest raw_copy_from_guest
+#define __raw_clear_guest raw_clear_guest
+
/* Is the guest handle a NULL reference? */
#define guest_handle_is_null(hnd) \
((hnd).p == NULL || xencomm_handle_is_null((hnd).p))
@@ -82,6 +94,13 @@ static inline unsigned long xencomm_inline_addr(const void
*handle)
#define copy_from_guest_offset(ptr, hnd, idx, nr) \
__copy_from_guest_offset(ptr, hnd, idx, nr)
+/*
+ * Clear an array of objects in guest context via a guest handle.
+ * Optionally specify an offset into the guest array.
+ */
+#define clear_guest_offset(hnd, idx, nr) \
+ __clear_guest_offset(hnd, idx, nr)
+
/* Copy sub-field of a structure from guest context via a guest handle. */
#define copy_field_from_guest(ptr, hnd, field) \
__copy_field_from_guest(ptr, hnd, field)
@@ -115,6 +134,11 @@ static inline unsigned long xencomm_inline_addr(const void
*handle)
xencomm_copy_from_guest(_d, _s, sizeof(*_d), _off); \
})
+#define __clear_guest_offset(hnd, idx, nr) ({ \
+ void *_d = (hnd).p; \
+ xencomm_clear_guest(_d, nr, idx); \
+})
+
#ifdef CONFIG_XENCOMM_MARK_DIRTY
extern void xencomm_mark_dirty(unsigned long addr, unsigned int len);
#else
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