Unverified Commit 4608c159 authored Apr 05, 2022 by Guo Ren Committed by Palmer Dabbelt May 17, 2022

riscv: compat: ptrace: Add compat_arch_ptrace implement

Now, you can use native gdb on riscv64 for rv32 app debugging.

$ uname -a
Linux buildroot 5.16.0-rc4-00036-gbef6b82fdf23-dirty #53 SMP Mon Dec 20 23:06:53 CST 2021 riscv64 GNU/Linux
$ cat /proc/cpuinfo
processor       : 0
hart            : 0
isa             : rv64imafdcsuh
mmu             : sv48

$ file /bin/busybox
/bin/busybox: setuid ELF 32-bit LSB shared object, UCB RISC-V, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-riscv32-ilp32d.so.1, for GNU/Linux 5.15.0, stripped
$ file /usr/bin/gdb
/usr/bin/gdb: ELF 32-bit LSB shared object, UCB RISC-V, version 1 (GNU/Linux), dynamically linked, interpreter /lib/ld-linux-riscv32-ilp32d.so.1, for GNU/Linux 5.15.0, stripped
$ /usr/bin/gdb /bin/busybox
GNU gdb (GDB) 10.2
Copyright (C) 2021 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html

>
...
Reading symbols from /bin/busybox...
(No debugging symbols found in /bin/busybox)
(gdb) b main
Breakpoint 1 at 0x8ddc
(gdb) r
Starting program: /bin/busybox
Failed to read a valid object file image from memory.

Breakpoint 1, 0x555a8ddc in main ()
(gdb) i r
ra             0x77df0b74       0x77df0b74
sp             0x7fdd3d10       0x7fdd3d10
gp             0x5567e800       0x5567e800 <bb_common_bufsiz1+160>
tp             0x77f64280       0x77f64280
t0             0x0      0
t1             0x555a6fac       1431990188
t2             0x77dd8db4       2011008436
fp             0x7fdd3e34       0x7fdd3e34
s1             0x7fdd3e34       2145205812
a0             0xffffffff       -1
a1             0x2000   8192
a2             0x7fdd3e3c       2145205820
a3             0x0      0
a4             0x7fdd3d30       2145205552
a5             0x555a8dc0       1431997888
a6             0x77f2c170       2012397936
a7             0x6a7c7a2f       1786542639
s2             0x0      0
s3             0x0      0
s4             0x555a8dc0       1431997888
s5             0x77f8a3a8       2012783528
s6             0x7fdd3e3c       2145205820
s7             0x5567cecc       1432866508
--Type <RET> for more, q to quit, c to continue without paging--
s8             0x1      1
s9             0x0      0
s10            0x55634448       1432568904
s11            0x0      0
t3             0x77df0bb8       2011106232
t4             0x42fc   17148
t5             0x0      0
t6             0x40     64
pc             0x555a8ddc       0x555a8ddc <main+28>
(gdb) si
0x555a78f0 in mallopt@plt ()
(gdb) c
Continuing.
BusyBox v1.34.1 (2021-12-19 22:39:48 CST) multi-call binary.
BusyBox is copyrighted by many authors between 1998-2015.
Licensed under GPLv2. See source distribution for detailed
copyright notices.

Usage: busybox [function [arguments]...]
   or: busybox --list[-full]
...
[Inferior 1 (process 107) exited normally]
(gdb) q

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220405071314.3225832-20-guoren@kernel.org


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

parent 7383ee05

arch/riscv/kernel/ptrace.c

+82 −5

Original line number	Diff line number	Diff line
		@@ -12,6 +12,7 @@
		#include <asm/thread_info.h>
		#include <asm/switch_to.h>
		#include <linux/audit.h>
		#include <linux/compat.h>
		#include <linux/ptrace.h>
		#include <linux/elf.h>
		#include <linux/regset.h>
		@@ -110,11 +111,6 @@ static const struct user_regset_view riscv_user_native_view = {
		.n = ARRAY_SIZE(riscv_user_regset),
		};

		const struct user_regset_view task_user_regset_view(struct task_struct task)
		{
		return &riscv_user_native_view;
		}

		struct pt_regs_offset {
		const char *name;
		int offset;
		@@ -272,3 +268,84 @@ __visible void do_syscall_trace_exit(struct pt_regs *regs)
		trace_sys_exit(regs, regs_return_value(regs));
		#endif
		}

		#ifdef CONFIG_COMPAT
		static int compat_riscv_gpr_get(struct task_struct *target,
		const struct user_regset *regset,
		struct membuf to)
		{
		struct compat_user_regs_struct cregs;

		regs_to_cregs(&cregs, task_pt_regs(target));

		return membuf_write(&to, &cregs,
		sizeof(struct compat_user_regs_struct));
		}

		static int compat_riscv_gpr_set(struct task_struct *target,
		const struct user_regset *regset,
		unsigned int pos, unsigned int count,
		const void kbuf, const void __user ubuf)
		{
		int ret;
		struct compat_user_regs_struct cregs;

		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &cregs, 0, -1);

		cregs_to_regs(&cregs, task_pt_regs(target));

		return ret;
		}

		static const struct user_regset compat_riscv_user_regset[] = {
		[REGSET_X] = {
		.core_note_type = NT_PRSTATUS,
		.n = ELF_NGREG,
		.size = sizeof(compat_elf_greg_t),
		.align = sizeof(compat_elf_greg_t),
		.regset_get = compat_riscv_gpr_get,
		.set = compat_riscv_gpr_set,
		},
		#ifdef CONFIG_FPU
		[REGSET_F] = {
		.core_note_type = NT_PRFPREG,
		.n = ELF_NFPREG,
		.size = sizeof(elf_fpreg_t),
		.align = sizeof(elf_fpreg_t),
		.regset_get = riscv_fpr_get,
		.set = riscv_fpr_set,
		},
		#endif
		};

		static const struct user_regset_view compat_riscv_user_native_view = {
		.name = "riscv",
		.e_machine = EM_RISCV,
		.regsets = compat_riscv_user_regset,
		.n = ARRAY_SIZE(compat_riscv_user_regset),
		};

		long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
		compat_ulong_t caddr, compat_ulong_t cdata)
		{
		long ret = -EIO;

		switch (request) {
		default:
		ret = compat_ptrace_request(child, request, caddr, cdata);
		break;
		}

		return ret;
		}
		#endif /* CONFIG_COMPAT */

		const struct user_regset_view task_user_regset_view(struct task_struct task)
		{
		#ifdef CONFIG_COMPAT
		if (test_tsk_thread_flag(task, TIF_32BIT))
		return &compat_riscv_user_native_view;
		else
		#endif
		return &riscv_user_native_view;
		}