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x86, ptrace: regset extensions to support xstate

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Add the xstate regset support which helps extend the kernel ptrace and the
core-dump interfaces to support AVX state etc.

This regset interface is designed to support all the future state that gets
supported using xsave/xrstor infrastructure.

Looking at the memory layout saved by "xsave", one can't say which state
is represented in the memory layout. This is because if a particular state is
in init state, in the xsave hdr it can be represented by bit '0'. And hence
we can't really say by the xsave header wether a state is in init state or
the state is not saved in the memory layout.

And hence the xsave memory layout available through this regset
interface uses SW usable bytes [464..511] to convey what state is represented
in the memory layout.

First 8 bytes of the sw_usable_bytes[464..467] will be set to OS enabled xstate
mask(which is same as the 64bit mask returned by the xgetbv's xCR0).

The note NT_X86_XSTATE represents the extended state information in the
core file, using the above mentioned memory layout.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20100211195614.802495327@sbs-t61.sc.intel.com>
Signed-off-by: Hongjiu Lu <hjl.tools@gmail.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Suresh Siddha
2010-02-11 11:50:59 -08:00
committed by H. Peter Anvin
parent 676ad58553
commit 5b3efd5008
7 changed files with 187 additions and 4 deletions
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58
arch/x86/include/asm/user.h
View File

@@ -1,5 +1,63 @@
#ifndef _ASM_X86_USER_H
#define _ASM_X86_USER_H
#ifdef CONFIG_X86_32
# include "user_32.h"
#else
# include "user_64.h"
#endif
#include <asm/types.h>
struct user_ymmh_regs {
/* 16 * 16 bytes for each YMMH-reg */
__u32 ymmh_space[64];
};
struct user_xsave_hdr {
__u64 xstate_bv;
__u64 reserved1[2];
__u64 reserved2[5];
};
/*
* The structure layout of user_xstateregs, used for exporting the
* extended register state through ptrace and core-dump (NT_X86_XSTATE note)
* interfaces will be same as the memory layout of xsave used by the processor
* (except for the bytes 464..511, which can be used by the software) and hence
* the size of this structure varies depending on the features supported by the
* processor and OS. The size of the structure that users need to use can be
* obtained by doing:
* cpuid_count(0xd, 0, &eax, &ptrace_xstateregs_struct_size, &ecx, &edx);
* i.e., cpuid.(eax=0xd,ecx=0).ebx will be the size that user (debuggers, etc.)
* need to use.
*
* For now, only the first 8 bytes of the software usable bytes[464..471] will
* be used and will be set to OS enabled xstate mask (which is same as the
* 64bit mask returned by the xgetbv's xCR0). Users (analyzing core dump
* remotely, etc.) can use this mask as well as the mask saved in the
* xstate_hdr bytes and interpret what states the processor/OS supports
* and what states are in modified/initialized conditions for the
* particular process/thread.
*
* Also when the user modifies certain state FP/SSE/etc through the
* ptrace interface, they must ensure that the xsave_hdr.xstate_bv
* bytes[512..519] of the memory layout are updated correspondingly.
* i.e., for example when FP state is modified to a non-init state,
* xsave_hdr.xstate_bv's bit 0 must be set to '1', when SSE is modified to
* non-init state, xsave_hdr.xstate_bv's bit 1 must to be set to '1', etc.
*/
#define USER_XSTATE_FX_SW_WORDS 6
#define USER_XSTATE_XCR0_WORD 0
struct user_xstateregs {
struct {
__u64 fpx_space[58];
__u64 xstate_fx_sw[USER_XSTATE_FX_SW_WORDS];
} i387;
struct user_xsave_hdr xsave_hdr;
struct user_ymmh_regs ymmh;
/* further processor state extensions go here */
};
#endif /* _ASM_X86_USER_H */