Commit 5e57fb7b authored by Pu Lehui's avatar Pu Lehui Committed by Daniel Borkmann
Browse files

riscv: Extend patch_text for multiple instructions 



Extend patch_text for multiple instructions. This is the preparaiton for
multiple instructions text patching in riscv BPF trampoline, and may be
useful for other scenario.

Signed-off-by: default avatarPu Lehui <pulehui@huawei.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Tested-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Reviewed-by: default avatarConor Dooley <conor.dooley@microchip.com>
Acked-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/bpf/20230215135205.1411105-2-pulehui@huaweicloud.com
parent 181127fb

arch/riscv/include/asm/patch.h

+1 −1
Original line number Diff line number Diff line
@@ -7,6 +7,6 @@ 
#define _ASM_RISCV_PATCH_H



int patch_text_nosync(void *addr, const void *insns, size_t len);

int patch_text(void *addr, u32 insn);

int patch_text(void *addr, u32 *insns, int ninsns);



#endif /* _ASM_RISCV_PATCH_H */

arch/riscv/kernel/patch.c

+12 −7
Original line number Diff line number Diff line
@@ -15,7 +15,8 @@ 


struct patch_insn {

	void *addr;

	u32 insn;

	u32 *insns;

	int ninsns;

	atomic_t cpu_count;

};
@@ -102,12 +103,15 @@ NOKPROBE_SYMBOL(patch_text_nosync); 
static int patch_text_cb(void *data)

{

	struct patch_insn *patch = data;

	int ret = 0;

	unsigned long len;

	int i, ret = 0;



	if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) {

		ret =

		    patch_text_nosync(patch->addr, &patch->insn,

					    GET_INSN_LENGTH(patch->insn));

		for (i = 0; ret == 0 && i < patch->ninsns; i++) {

			len = GET_INSN_LENGTH(patch->insns[i]);

			ret = patch_text_nosync(patch->addr + i * len,

						&patch->insns[i], len);

		}

		atomic_inc(&patch->cpu_count);

	} else {

		while (atomic_read(&patch->cpu_count) <= num_online_cpus())
@@ -119,11 +123,12 @@ static int patch_text_cb(void *data) 
}

NOKPROBE_SYMBOL(patch_text_cb);



int patch_text(void *addr, u32 insn)

int patch_text(void *addr, u32 *insns, int ninsns)

{

	struct patch_insn patch = {

		.addr = addr,

		.insn = insn,

		.insns = insns,

		.ninsns = ninsns,

		.cpu_count = ATOMIC_INIT(0),

	};

arch/riscv/kernel/probes/kprobes.c

+8 −7
Original line number Diff line number Diff line
@@ -23,13 +23,14 @@ post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *); 


static void __kprobes arch_prepare_ss_slot(struct kprobe *p)

{

	u32 insn = __BUG_INSN_32;

	unsigned long offset = GET_INSN_LENGTH(p->opcode);



	p->ainsn.api.restore = (unsigned long)p->addr + offset;



	patch_text(p->ainsn.api.insn, p->opcode);

	patch_text(p->ainsn.api.insn, &p->opcode, 1);

	patch_text((void *)((unsigned long)(p->ainsn.api.insn) + offset),

		   __BUG_INSN_32);

		   &insn, 1);

}



static void __kprobes arch_prepare_simulate(struct kprobe *p)
@@ -114,16 +115,16 @@ void *alloc_insn_page(void) 
/* install breakpoint in text */

void __kprobes arch_arm_kprobe(struct kprobe *p)

{

	if ((p->opcode & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)

		patch_text(p->addr, __BUG_INSN_32);

	else

		patch_text(p->addr, __BUG_INSN_16);

	u32 insn = (p->opcode & __INSN_LENGTH_MASK) == __INSN_LENGTH_32 ?

		   __BUG_INSN_32 : __BUG_INSN_16;



	patch_text(p->addr, &insn, 1);

}



/* remove breakpoint from text */

void __kprobes arch_disarm_kprobe(struct kprobe *p)

{

	patch_text(p->addr, p->opcode);

	patch_text(p->addr, &p->opcode, 1);

}



void __kprobes arch_remove_kprobe(struct kprobe *p)