libunw: riscv: simplify architecture test

Test ARCH rather than CFG_RV32_$(sm) and CFG_RV64_$(sm).

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Etienne Carriere <etien

libunw: riscv: simplify architecture test

Test ARCH rather than CFG_RV32_$(sm) and CFG_RV64_$(sm).

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

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libunw: arm: unwind_arm32.c should be compiled only for Arm

unwind_arm32.c contains functions to unwind arm32 code. This is used
when libunw is built for arm32 or arm64, in other words when ARCH=arm

libunw: arm: unwind_arm32.c should be compiled only for Arm

unwind_arm32.c contains functions to unwind arm32 code. This is used
when libunw is built for arm32 or arm64, in other words when ARCH=arm.
Other architectures (such as ARCH=riscv) obviously don't need it.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Etienne Carriere <etienne.carriere@foss.st.com>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>

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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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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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