libunw: Implement RISC-V stack unwinding

This patch implements stack unwinding for RISC-V architecture into
libunw. In RISC-V, the caller stores its frame pointer into register
s0 before calling the

libunw: Implement RISC-V stack unwinding

This patch implements stack unwinding for RISC-V architecture into
libunw. In RISC-V, the caller stores its frame pointer into register
s0 before calling the function. In the prologue of callee function,
the return address and the caller's frame pointer are saved into the
bottom of the callee's stack frame, and the callee's frame pointer is
also calculated and stored into s0 within the process of callee
function. Therefore, the caller's stack frame can be traced back from
the callee's stack frame.

The following steps describe the stack unwinding on RV64 system:
1. When an exception occurs, we get the current frame pointer from
trapped register s0/fp.
2. Get the ra from the memory address (fp-0x8).
3. Get the caller's frame pointer from the memory address (fp-0x10).
4. Update the caller's pc as (ra-0x4), this is information we want from
stack unwinding.
5. Repeat the step 2 to step 4, until we exceed the stack frame of the
thread.

Signed-off-by: Alvin Chang <alvinga@andestech.com>
Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Etienne Carriere <etienne.carriere@foss.st.com>

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ldelf: strip PAC from TA addresses

When pointer authentication is enables for TA's, the LR values
saved in the stack will have PAC which must be stripped off
when unwinding the stack.

Signed-off-by

ldelf: strip PAC from TA addresses

When pointer authentication is enables for TA's, the LR values
saved in the stack will have PAC which must be stripped off
when unwinding the stack.

Signed-off-by: Ruchika Gupta <ruchika.gupta@linaro.org>
Acked-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>

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Add unwind library (libunw)

Adds libunw to consolidate the stack unwinding code found in
ldelf/unwind_arm{32,64}.c and core/arch/arm/kernel/unwind_arm{32,64}.c.

The library is called "libunw" rathe

Add unwind library (libunw)

Adds libunw to consolidate the stack unwinding code found in
ldelf/unwind_arm{32,64}.c and core/arch/arm/kernel/unwind_arm{32,64}.c.

The library is called "libunw" rather than "libunwind" to avoid
confusion with the GNU libunwind [1]. The header file is <unw/unwind.h>
to avoid a conflict with GCC's <unwind.h>.

Link: [1] https://www.nongnu.org/libunwind
Signed-off-by: Jerome Forissier <jerome@forissier.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>

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