uc_access(3)uc_access(3)NAME
uc_access: __uc_get_ar(), __uc_get_ar_bsp(), __uc_get_ar_bspstore(),
__uc_get_ar_ccv(), __uc_get_ar_csd(), __uc_get_ar_ec(),
__uc_get_ar_fpsr(), __uc_get_ar_lc(), __uc_get_ar_pfs(),
__uc_get_ar_rsc(), __uc_get_ar_ssd(), __uc_get_ar_unat(),
__uc_get_brs(), __uc_get_cfm(), __uc_get_cr(), __uc_get_ed(),
__uc_get_frs(), __uc_get_grs(), __uc_get_ip(), __uc_get_prs(),
__uc_get_reason(), __uc_get_rsebs(), __uc_get_rsebs64(), __uc_get_um(),
__uc_set_ar(), __uc_set_ar_ccv(), __uc_set_ar_csd(), __uc_set_ar_ec(),
__uc_set_ar_fpsr(), __uc_set_ar_lc(), __uc_set_ar_pfs(),
__uc_set_ar_rsc(), __uc_set_ar_ssd(), __uc_set_ar_unat(),
__uc_set_brs(), __uc_set_cfm(), __uc_set_ed(), __uc_set_frs(),
__uc_set_grs(), __uc_set_ip(), __uc_set_prs(), __uc_set_rsebs(),
__uc_set_rsebs64(), __uc_set_um() - user context access (ucontext_t)
SYNOPSIS
Command: [flag]... file... [library]...
DESCRIPTION
The Ucontext Access interfaces allow an application to access the
Integrity register state contained inside the opaque structure within
the user context structure.
In all these interfaces, is a pointer to a passed to the application as
the third argument to a signal handler, allocated by the user and
filled in with or read from an application file.
Because a syscall occurs on a function call boundary, contexts created
in a syscall omit scratch registers and other specific values as
detailed below.
To use any of these functions, link in the ucontext access library by
specifying on the compiler or linker command line.
Individual Interface Descriptions
Returns (in the location referenced by the
argument) zero if the context was created in a syscall or a
non-zero value if the context was created while handling an
interruption that occurred while running user code.
Returns (in the
array) the saved values of the Static General Registers in
the range through + inclusive, and (in the argument) the cor‐
responding NaT bit values. Only Static General Registers
(GR1-GR31) may be read with this interface. Stacked General
Registers (GR32-GR127) must be read from the RSE backing
store, or the RSE Backing Store overflow area. (See below.)
The NaT bits corresponding to the requested General Registers
will be in the corresponding bits of NaT. For example, rep‐
resents the Nat Bit for GR5.
If the context was created in a syscall, scratch registers
(GR2, GR3 and GR14-GR31) will read as
Overwrites the saved values of the Static General Registers in the
range
through + inclusive, with the contents of the first elements
of the array, and overwrites the corresponding NaT bits with
bits from the argument. Only Static General Registers
(GR1-GR31) may be written with this interface. Stacked Gen‐
eral Registers (GR32-GR127) must be written to the RSE back‐
ing store, or the RSE Backing Store overflow area. (See
below.)
The NaT bits corresponding to the specified General Registers
must be in the corresponding bits of NaT. For example, the
NaT bit for GR5 will be overwritten with
If the context was created in a syscall, an attempt to write
scratch registers (GR2, GR3 and GR14-GR31) will return
Returns (in the
array) the saved values of the Floating-Point Registers in
the range through + inclusive.
If the context was created in a syscall, scratch registers
(FR6-FR15 and FR32-FR127) will read as
Overwrites the saved values of the Floating-Point Registers in the
range
through + inclusive, with the contents of the first elements
of the array.
If the context was created in a syscall, an attempt to write
scratch registers (FR6-FR15 and FR32-FR127) will return An
attempt to set bits {127:82} of an FP value will return
Returns (in the location referenced by the
argument) the saved values of the Predicate Registers.
If the context was created in a syscall, scratch predicates
(PR6-PR15) will read as
Overwrites the saved values of the Predicate Registers with
If the context was created in a syscall, an attempt to set
scratch predicates (PR6-PR15) will return
Attempts to clear PR[0] will be silently ignored.
Returns (in the
array) the saved values of the Branch Registers in the range
through + inclusive.
If the context was created in a syscall, scratch registers
(BR6-BR7) will read as
Overwrites the saved values of the Branch Registers in the range
through + inclusive, with the contents of the first elements
of the array.
If the context was created in a syscall, an attempt to write
scratch registers (BR6-BR7) will return
Returns (in the
argument) the saved value of the Instruction Pointer Regis‐
ter.
If the context was created while handling an interruption,
will be that of the next instruction to execute. The
instruction slot will be indicated by a value of or in the
low-order 2 bits of the For traps and interrupts, it will
point to the next instruction. For faults, it will point to
the faulting instruction. If the context was created in a
syscall, will be the return pointer from the system call.
The low-order 2 bits of the will be
Overwrites the saved value of the Instruction Pointer Register with
If the context was created while handling an interruption,
the instruction slot indicated by the 2 low-order bits of
will be the next instruction to execute. If the context was
created in a syscall, an attempt to set the instruction slot
to a non-zero value will return
Returns (in the
argument) the saved value of the Current Frame Marker Regis‐
ter.
If the context was created in a syscall, will be the frame
marker corresponding to the function that called the kernel.
Overwrites the saved value of the Current Frame Marker Register with
Returns (in the
argument) the saved value of the User Mask Register.
Overwrites the saved User Mask Register with
An attempt to set reserved bits will return
Returns (in the low-order bit of the
argument) the saved value of the Exception Deferral Bit.
This bit is only saved in interruption contexts. An attempt
to read it from a context saved in a syscall will return
Overwrites the saved Exception Deferral Bit value with the low-order
bit of the
specified. This bit is only saved in interruption contexts.
An attempt to write it in a context saved in a syscall will
return An attempt to set it if CR.ISR.ED is not set will
return
Returns (in the
argument) the saved value of the register.
Overwrites the saved value of the
register with
Returns (in the
argument) the saved value of the register. By convention,
this value reflects the effects of the instruction used to
enter a syscall or the instruction used in handling an inter‐
ruption. To find the value that will be in when the next
instruction is executed the caller must:
1) Call to determine whether the context was created in a
syscall or while handling an interruption.
2) Call to fetch the current frame marker.
3) Adjust the value by (for a syscall context) or (for an
interruption context).
Returns (in the
argument) the saved value of the register.
Returns (in the
argument) the saved value of the register. If the context
was created in a syscall, the value is undefined.
Overwrites the saved value of the
register with If the context was created in a syscall, this
call returns with no other side-effects.
Returns (in the
argument) the saved value of the register. If the context
was created in a syscall, the value is undefined.
Overwrites the saved value of the
register with If the context was created in a syscall, this
call returns with no other side-effects.
Returns (in the
argument) the saved value of the register. If the context
was created in a syscall, the value is undefined.
Overwrites the saved value of the
register with If the context was created in a syscall, this
call returns with no other side-effects.
Returns (in the
argument) the saved value of the register.
Overwrites the saved value of the
register with
Returns (in the
argument) the saved value of the register.
Overwrites the saved value of the
register with
Returns (in the
argument) the saved value of the register. In a syscall con‐
text, the value returned is undefined. Use to read the cur‐
rent frame marker and to read the current epilog count.
Overwrites the saved value of the
register with If the context was created in a syscall,
returns with no other side-effects.
Returns (in the
argument) the saved value of the register.
Overwrites the saved value of the
register with
Returns (in the
argument) the saved value of the register.
Overwrites the saved value of the
register with the low-order 6 bits of
Returns (in the
argument) the saved value of the Application Register speci‐
fied by
Overwrites the saved value of the Application Register specified by
with
The following Application Registers may be specified:
┌────┬─────────────┬────┬────┐
│Reg │Register │Get │Set │
├────┼─────────────┼────┼────┤
│16 │AR_RSC │X │X │
├────┼─────────────┼────┼────┤
│17 │AR_BSP │X │ │
├────┼─────────────┼────┼────┤
│18 │AR_BSPSTORE │X │X │
├────┼─────────────┼────┼────┤
│25 │AR_AR_CSD(*) │X │X │
├────┼─────────────┼────┼────┤
│26 │AR_AR_SSD(*) │X │X │
├────┼─────────────┼────┼────┤
│32 │AR_AR_CCV(*) │X │X │
├────┼─────────────┼────┼────┤
│36 │AR_UNAT │X │X │
├────┼─────────────┼────┼────┤
│40 │AR_FPSR │X │X │
├────┼─────────────┼────┼────┤
│64 │AR_PFS(+) │X │X │
├────┼─────────────┼────┼────┤
│65 │AR_LC │X │X │
├────┼─────────────┼────┼────┤
│66 │AR_EC │X │X │
└────┴─────────────┴────┴────┘
*
and are scratch registers. If the context was created in a
syscall, it will read as 0. An attempt to write it will
return
+ Note the caller should consult the unwind information for
the function preceding the delivery of the signal to deter‐
mine if the register contained valid data.
Returns (in the
argument) the saved value of the Control Register specified
by
The following Control Registers may be specified:
┌────┬─────────┬────────────────────────────────────────────────┐
│Reg │Register │Notes │
├────┼─────────┼────────────────────────────────────────────────┤
│17 │CR_ISR │ │
├────┼─────────┼────────────────────────────────────────────────┤
│20 │CR_IFA │ Only valid for certain types of interruptions. │
├────┼─────────┼────────────────────────────────────────────────┤
│22 │CR_IIPA │ │
└────┴─────────┴────────────────────────────────────────────────┘
If the context was created in a syscall, the control registers will
read as 0.
When a signal handler is invoked, the kernel attempts to write
all dirty RSE
registers to the original RSE backing store. If it is
unable to do this (that is, if the memory is not
mapped) the kernel will write remaining dirty regis‐
ters to an overflow area within the These interfaces
are provided to access those values saved in this
overflow area.
Use to fetch the and values.
┌──────────────────────────────────────────┬────────────────────────┐
│If the address of the value you want is │Use │
├──────────────────────────────────────────┼────────────────────────┤
│addr < AR.BSPSTORE │direct read/write │
├──────────────────────────────────────────┼────────────────────────┤
│AR.BSPSTORE <= addr < AR.BSP │__uc_[gs]et_rsebs{64}() │
├──────────────────────────────────────────┼────────────────────────┤
│Special case for the last NaT collection: │__uc_[gs]et_rsebs{64}() │
│addr == AR.BSP | 0x1f8 │ │
└──────────────────────────────────────────┴────────────────────────┘
The bits may be split between the value and the overflow
area.
┌──────────────────────────────────────┬───────────────────────────────────┐
│Address │Where to find the NaT │
├──────────────────────────────────────┼───────────────────────────────────┤
│addr < AR.BSPSTORE & ~0x1ff │direct read/write of backing store │
├──────────────────────────────────────┼───────────────────────────────────┤
│AR.BSPSTORE & ~0x1ff <= addr < AR.BSP │__uc_[gs]et_rsebs{64}(addr|0x1f8) │
└──────────────────────────────────────┴───────────────────────────────────┘
For 32-bit callers,
and will swizzle the addr argument.
are provided for 32-bit callers reading a generated
within a 64-bit application. They differ from in that
the addr argument will not be swizzled. are only
included in 32-bit versions of the library.
RETURN VALUE
Upon successful completion, all the interfaces return 0 to indi‐
cate success and return if passed invalid arguments.
ERRORS
The Ucontext Access interfaces will fail if any of the following
conditions are encountered:
For any of the interfaces listed above, the
argument is NULL, or points to a with an
invalid version or size.
For the or calls the range of registers specified
by and included a value outside the range
1 to 31 inclusive.
For the call, was created by a syscall and the
range of registers specified by and
included a scratch register.
For the or calls the range of registers specified
by and included a value outside the range
2 to 127 inclusive.
For the call, was created by a syscall and the
range of registers specified by and
included a scratch register or an attempt
is made to set bits {127:82} of an FP
value.
For the call, was created by a syscall and
included a set scratch bit or bits.
For the or calls the range of registers specified
by and included a value outside the range
0 to 7 inclusive.
For the call, was created by a syscall and the
range of registers specified by and
included a scratch register.
For the call, was created by a syscall and the
low-order two bits of are not zero, or was
not created by a syscall and the low-order
two bits of are
For the call, bits outside the range 37:0 are set.
For the call, bits outside the range 5:1 are set.
For the or calls, a reserved field is non-zero.
For the or calls, an invalid register is speci‐
fied.
For the call, specifies a valid register and
includes reserved bits that are set.
For the or calls, was created in a system call.
For the call, includes bits set other than the
low-order bit or the low-order bit is set
and the saved CR.ISR.ED bit is clear.
For the or calls, the range of memory locations
specified by and includes values outside
the range (inclusive) and (exclusive) or
if specifying the last NaT collection
location, != 1
WARNINGS
Only minimal argument checking is performed. The caller must
take care not to write invalid or out-of-range values to any
register or register field. The effects of returning from a
signal handler or calling after overwriting any register with
invalid or out-of-range values are undefined.
is deprecated and should be used only by legacy applications.
and are the recommended replacements.
is deprecated and should be used only by legacy applications.
and are the recommended replacements. is deprecated and should
be used only by legacy applications.
AUTHOR
The UContext Access library was developed by HP.
FILES
Prototypes for the interfaces
SEE ALSOgetcontext(2), sigaction(2), core(4), signal(5), <ucontext.h>.
Integrity Systems Onlyuc_access(3)
