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Subject[PATCH 08/33] x86/fpu: Clarify parameter names in the copy_xstate_to_*() methods
Date
Right now there's a confusing mixture of 'offset' and 'size' parameters:

- __copy_xstate_to_*() input parameter 'end_pos' not not really an offset,
but the full size of the copy to be performed.

- input parameter 'count' to copy_xstate_to_*() shadows that of
__copy_xstate_to_*()'s 'count' parameter name - but the roles
are different: the first one is the total number of bytes to
be copied, while the second one is a partial copy size.

To unconfuse all this, use a consistent set of parameter names:

- 'size' is the partial copy size within a single xstate component
- 'size_total' is the total copy requested
- 'offset_start' is the requested starting offset.
- 'offset' is the offset within an xstate component.

No change in functionality.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/fpu/xstate.h | 4 ++--
arch/x86/kernel/fpu/xstate.c | 44 ++++++++++++++++++++++----------------------
2 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index e4430b84939d..fed6617a1079 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -48,8 +48,8 @@ void fpu__xstate_clear_all_cpu_caps(void);
void *get_xsave_addr(struct xregs_state *xsave, int xstate);
const void *get_xsave_field_ptr(int xstate_field);
int using_compacted_format(void);
-int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int pos, unsigned int count);
-int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int pos, unsigned int count);
+int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
+int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
int copy_user_to_xstate(const void *kbuf, const void __user *ubuf,
struct xregs_state *xsave);
#endif
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 1f50fdaf4c5a..c13083579655 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -927,15 +927,15 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
static inline int
__copy_xstate_to_kernel(void *kbuf,
const void *data,
- unsigned int pos, unsigned int count, int end_pos)
+ unsigned int offset, unsigned int size, int size_total)
{
- if (!count)
+ if (!size)
return 0;

- if (end_pos < 0 || pos < end_pos) {
- unsigned int copy = end_pos < 0 ? count : min(count, end_pos - pos);
+ if (size_total < 0 || offset < size_total) {
+ unsigned int copy = size_total < 0 ? size : min(size, size_total - offset);

- memcpy(kbuf + pos, data, copy);
+ memcpy(kbuf + offset, data, copy);
}
return 0;
}
@@ -947,7 +947,7 @@ __copy_xstate_to_kernel(void *kbuf,
* It supports partial copy but pos always starts from zero. This is called
* from xstateregs_get() and there we check the CPU has XSAVES.
*/
-int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int pos, unsigned int count)
+int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
{
unsigned int offset, size;
int ret, i;
@@ -956,7 +956,7 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int po
/*
* Currently copy_regset_to_user() starts from pos 0:
*/
- if (unlikely(pos != 0))
+ if (unlikely(offset_start != 0))
return -EFAULT;

/*
@@ -972,7 +972,7 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int po
offset = offsetof(struct xregs_state, header);
size = sizeof(header);

- ret = __copy_xstate_to_kernel(kbuf, &header, offset, size, count);
+ ret = __copy_xstate_to_kernel(kbuf, &header, offset, size, size_total);
if (ret)
return ret;

@@ -986,11 +986,11 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int po
offset = xstate_offsets[i];
size = xstate_sizes[i];

- ret = __copy_xstate_to_kernel(kbuf, src, offset, size, count);
+ ret = __copy_xstate_to_kernel(kbuf, src, offset, size, size_total);
if (ret)
return ret;

- if (offset + size >= count)
+ if (offset + size >= size_total)
break;
}

@@ -1002,7 +1002,7 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int po
offset = offsetof(struct fxregs_state, sw_reserved);
size = sizeof(xstate_fx_sw_bytes);

- ret = __copy_xstate_to_kernel(kbuf, xstate_fx_sw_bytes, offset, size, count);
+ ret = __copy_xstate_to_kernel(kbuf, xstate_fx_sw_bytes, offset, size, size_total);
if (ret)
return ret;

@@ -1010,15 +1010,15 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int po
}

static inline int
-__copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int pos, unsigned int count, int end_pos)
+__copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, int size_total)
{
- if (!count)
+ if (!size)
return 0;

- if (end_pos < 0 || pos < end_pos) {
- unsigned int copy = end_pos < 0 ? count : min(count, end_pos - pos);
+ if (size_total < 0 || offset < size_total) {
+ unsigned int copy = size_total < 0 ? size : min(size, size_total - offset);

- if (__copy_to_user(ubuf + pos, data, copy))
+ if (__copy_to_user(ubuf + offset, data, copy))
return -EFAULT;
}
return 0;
@@ -1030,7 +1030,7 @@ __copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int pos, uns
* zero. This is called from xstateregs_get() and there we check the CPU
* has XSAVES.
*/
-int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int pos, unsigned int count)
+int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
{
unsigned int offset, size;
int ret, i;
@@ -1039,7 +1039,7 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
/*
* Currently copy_regset_to_user() starts from pos 0:
*/
- if (unlikely(pos != 0))
+ if (unlikely(offset_start != 0))
return -EFAULT;

/*
@@ -1055,7 +1055,7 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
offset = offsetof(struct xregs_state, header);
size = sizeof(header);

- ret = __copy_xstate_to_user(ubuf, &header, offset, size, count);
+ ret = __copy_xstate_to_user(ubuf, &header, offset, size, size_total);
if (ret)
return ret;

@@ -1069,11 +1069,11 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
offset = xstate_offsets[i];
size = xstate_sizes[i];

- ret = __copy_xstate_to_user(ubuf, src, offset, size, count);
+ ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total);
if (ret)
return ret;

- if (offset + size >= count)
+ if (offset + size >= size_total)
break;
}

@@ -1085,7 +1085,7 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
offset = offsetof(struct fxregs_state, sw_reserved);
size = sizeof(xstate_fx_sw_bytes);

- ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, count);
+ ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, size_total);
if (ret)
return ret;

--
2.11.0
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