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x86/fpu: Split copy_xstate_to_user() into copy_xstate_to_kernel() & copy_xstate_to_user() 

copy_xstate_to_user() is a weird API - in part due to a bad API inherited
from the regset APIs.

But don't propagate that bad API choice into the FPU code - so as a first
step split the API into kernel and user buffer handling routines.

(Also split the xstate_copyout() internal helper.)

The split API is a dumb duplication that should be obviously correct, the
real splitting will be done in the next patch.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.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>
Link: http://lkml.kernel.org/r/20170923130016.21448-3-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Ingo Molnar 2017-09-23 14:59:45 +02:00
parent 656f083116
commit f0d4f30a7f
3 changed files with 109 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/include/asm/fpu/xstate.h
View File

@ -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_user(unsigned int pos, unsigned int count, void *kbuf,
void __user *ubuf, struct xregs_state *xsave);
int copy_xstate_to_kernel(unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf, struct xregs_state *xsave);
int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf, struct xregs_state *xsave);
int copy_user_to_xstate(const void *kbuf, const void __user *ubuf,
struct xregs_state *xsave);
#endif

5
arch/x86/kernel/fpu/regset.c
View File

@ -92,7 +92,10 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
fpu__activate_fpstate_read(fpu);
if (using_compacted_format()) {
ret = copy_xstate_to_user(pos, count, kbuf, ubuf, xsave);
if (kbuf)
ret = copy_xstate_to_kernel(pos, count, kbuf, ubuf, xsave);
else
ret = copy_xstate_to_user(pos, count, kbuf, ubuf, xsave);
} else {
fpstate_sanitize_xstate(fpu);
/*

110
arch/x86/kernel/fpu/xstate.c
View File

@ -924,10 +924,106 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
* This is similar to user_regset_copyout(), but will not add offset to
* the source data pointer or increment pos, count, kbuf, and ubuf.
*/
static inline int xstate_copyout(unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf,
const void *data, const int start_pos,
const int end_pos)
static inline int
__copy_xstate_to_kernel(unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf,
const void *data, const int start_pos,
const int end_pos)
{
if ((count == 0) || (pos < start_pos))
return 0;
if (end_pos < 0 || pos < end_pos) {
unsigned int copy = (end_pos < 0 ? count : min(count, end_pos - pos));
if (kbuf) {
memcpy(kbuf + pos, data, copy);
} else {
if (__copy_to_user(ubuf + pos, data, copy))
return -EFAULT;
}
}
return 0;
}
/*
* Convert from kernel XSAVES compacted format to standard format and copy
* to a kernel-space ptrace buffer.
*
* 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(unsigned int pos, unsigned int count, void *kbuf,
void __user *ubuf, struct xregs_state *xsave)
{
unsigned int offset, size;
int ret, i;
struct xstate_header header;
/*
* Currently copy_regset_to_user() starts from pos 0:
*/
if (unlikely(pos != 0))
return -EFAULT;
/*
* The destination is a ptrace buffer; we put in only user xstates:
*/
memset(&header, 0, sizeof(header));
header.xfeatures = xsave->header.xfeatures;
header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
/*
* Copy xregs_state->header:
*/
offset = offsetof(struct xregs_state, header);
size = sizeof(header);
ret = __copy_xstate_to_kernel(offset, size, kbuf, ubuf, &header, 0, count);
if (ret)
return ret;
for (i = 0; i < XFEATURE_MAX; i++) {
/*
* Copy only in-use xstates:
*/
if ((header.xfeatures >> i) & 1) {
void *src = __raw_xsave_addr(xsave, 1 << i);
offset = xstate_offsets[i];
size = xstate_sizes[i];
ret = __copy_xstate_to_kernel(offset, size, kbuf, ubuf, src, 0, count);
if (ret)
return ret;
if (offset + size >= count)
break;
}
}
/*
* Fill xsave->i387.sw_reserved value for ptrace frame:
*/
offset = offsetof(struct fxregs_state, sw_reserved);
size = sizeof(xstate_fx_sw_bytes);
ret = __copy_xstate_to_kernel(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count);
if (ret)
return ret;
return 0;
}
static inline int
__copy_xstate_to_user(unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf,
const void *data, const int start_pos,
const int end_pos)
{
if ((count == 0) || (pos < start_pos))
return 0;
@ -977,7 +1073,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf,
offset = offsetof(struct xregs_state, header);
size = sizeof(header);
ret = xstate_copyout(offset, size, kbuf, ubuf, &header, 0, count);
ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, &header, 0, count);
if (ret)
return ret;
@ -992,7 +1088,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf,
offset = xstate_offsets[i];
size = xstate_sizes[i];
ret = xstate_copyout(offset, size, kbuf, ubuf, src, 0, count);
ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, src, 0, count);
if (ret)
return ret;
@ -1009,7 +1105,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf,
offset = offsetof(struct fxregs_state, sw_reserved);
size = sizeof(xstate_fx_sw_bytes);
ret = xstate_copyout(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count);
ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count);
if (ret)
return ret;