libproc: add LoongArch support

[zhaoxiaoqiang007_gmail.com]

Summary

Add the LoongArch breakpoint instruction.

Signed-off-by: Xiaoqiang Zhao <[e-mail]>
Signed-off-by: yu shan wei <[e-mail]>

[zishun.yi.dev_gmail.com]

Should we also update the proc_regs.c?

[zhaoxiaoqiang007_gmail.com]

In D59896#1374946, @zishun.yi.dev_gmail.com wrote:

Should we also update the proc_regs.c?

done!

[shipujin.t_gmail.com]

break 0 is BRK_DEFAULT, not a user-breakpoint code, use break 0x4 (BRK_USERBP)

lib/libproc/proc_bkpt.c

66

break 0 is BRK_DEFAULT, not a user-breakpoint code, use break 0x4 (BRK_USERBP)

break 0 is the semantically unspecified default code rather than the user breakpoint code — the code_break is a semantic argument reserved for the handler (LoongArch Reference Manual Vol.1 §2.2.10.2), and the ecosystem has already assigned 0=DEFAULT, 4=BRK_USERBP "User bp (used by debuggers)", and 5=BRK_SSTEPBP. Therefore the user breakpoint should use the dedicated 0x4(the encoding has been verified by llvm-mc: break → [0x04,0x00,0x2a,0x00] = 0x002a0004).

Suggested change to:

#define	BREAKPOINT_INSTR	0x002a0004	/* break 0x4 (BRK_USERBP) */

[zhaoxiaoqiang007_gmail.com]

add missing reg value set/get
use break 0x4 for user break point

[shipujin.t_gmail.com]

LGTM.

[zhaoxiaoqiang007_gmail.com]

match kernel register rename