There are xstate context copy functions that used in ptrace() and signal
return paths. They serve callers to read (or write) xstate values in the
task->fpu's buffer, or to get initial values. With dynamic user states, a
component's position in the buffer may vary and the initial value is not
always stored in init_fpstate.
Change the helpers to find a component's offset accordingly (either lookup
table or calculation).
When copying an initial value, explicitly check the init_fpstate coverage.
If not found, reset the memory in the destination. Otherwise, copy values
from init_fpstate.
No functional change until the kernel supports dynamic user states.
Signed-off-by: Chang S. Bae <chang.seok....@intel.com>
Reviewed-by: Len Brown <len.br...@intel.com>
Cc: x...@kernel.org
Cc: linux-kernel@vger.kernel.org
---
arch/x86/kernel/fpu/xstate.c | 55 +++++++++++++++++++++++++++---------
1 file changed, 41 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 556ae8593806..b9261ab4e5e2 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -245,12 +245,14 @@ void fpstate_sanitize_xstate(struct fpu *fpu)
if (!(xfeatures & XFEATURE_MASK_SSE))
memset(&fx->xmm_space[0], 0, 256);
+ /* Make sure 'xfeatures' to be a subset of fpu->state_mask */
+ xfeatures = ((xfeatures_mask_user() & fpu->state_mask) & ~xfeatures);
/*
* First two features are FPU and SSE, which above we handled
* in a special way already:
*/
feature_bit = 0x2;
- xfeatures = (xfeatures_mask_user() & ~xfeatures) >> 2;
+ xfeatures >>= 0x2;
/*
* Update all the remaining memory layouts according to their
@@ -259,12 +261,15 @@ void fpstate_sanitize_xstate(struct fpu *fpu)
*/
while (xfeatures) {
if (xfeatures & 0x1) {
- int offset = xstate_comp_offsets[feature_bit];
- int size = xstate_sizes[feature_bit];
-
- memcpy((void *)xsave + offset,
- (void *)&init_fpstate.xsave + offset,
- size);
+ unsigned int offset = get_xstate_comp_offset(fpu,
feature_bit);
+ unsigned int size = xstate_sizes[feature_bit];
+
+ if (get_init_fpstate_mask() & BIT_ULL(feature_bit))
+ memcpy((void *)xsave + offset,
+ (void *)&init_fpstate.xsave + offset,
+ size);
+ else
+ memset((void *)xsave + offset, 0, size);
}
xfeatures >>= 1;
@@ -1238,7 +1243,10 @@ static void fill_gap(struct membuf *to, unsigned *last,
unsigned offset)
{
if (*last >= offset)
return;
- membuf_write(to, (void *)&init_fpstate.xsave + *last, offset - *last);
+ if (offset <= get_init_fpstate_size())
+ membuf_write(to, (void *)&init_fpstate.xsave + *last, offset -
*last);
+ else
+ membuf_zero(to, offset - *last);
*last = offset;
}
@@ -1246,7 +1254,10 @@ static void copy_part(struct membuf *to, unsigned *last,
unsigned offset,
unsigned size, void *from)
{
fill_gap(to, last, offset);
- membuf_write(to, from, size);
+ if (from)
+ membuf_write(to, from, size);
+ else
+ membuf_zero(to, size);
*last = offset + size;
}
@@ -1298,12 +1309,22 @@ void copy_xstate_to_kernel(struct membuf to, struct fpu
*fpu)
sizeof(header), &header);
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
+ u64 mask = BIT_ULL(i);
+ void *src;
/*
- * Copy only in-use xstates:
+ * Copy only in-use xstate at first. If the feature is enabled,
+ * find the init value, whether stored in init_fpstate or simply
+ * zeros, and then copy them.
*/
- if ((header.xfeatures >> i) & 1) {
- void *src = __raw_xsave_addr(fpu, i);
-
+ if (header.xfeatures & mask) {
+ src = __raw_xsave_addr(fpu, i);
+ copy_part(&to, &last, xstate_offsets[i],
+ xstate_sizes[i], src);
+ } else if (xfeatures_mask_user() & mask) {
+ if (get_init_fpstate_mask() & mask)
+ src = (void *)&init_fpstate.xsave + last;
+ else
+ src = NULL;
copy_part(&to, &last, xstate_offsets[i],
xstate_sizes[i], src);
}
@@ -1337,6 +1358,9 @@ int copy_kernel_to_xstate(struct fpu *fpu, const void
*kbuf)
if (hdr.xfeatures & mask) {
void *dst = __raw_xsave_addr(fpu, i);
+ if (!dst)
+ continue;
+
offset = xstate_offsets[i];
size = xstate_sizes[i];
@@ -1394,6 +1418,9 @@ int copy_user_to_xstate(struct fpu *fpu, const void
__user *ubuf)
if (hdr.xfeatures & mask) {
void *dst = __raw_xsave_addr(fpu, i);
+ if (!dst)
+ continue;
+
offset = xstate_offsets[i];
size = xstate_sizes[i];
@@ -1476,7 +1503,7 @@ void copy_supervisor_to_kernel(struct fpu *fpu)
continue;
/* Move xfeature 'i' into its normal location */
- memmove(xbuf + xstate_comp_offsets[i],
+ memmove(xbuf + get_xstate_comp_offset(fpu, i),
xbuf + xstate_supervisor_only_offsets[i],
xstate_sizes[i]);
}
--
2.17.1
