Unverified Commit 51781ce8 authored by Samuel Holland's avatar Samuel Holland Committed by Palmer Dabbelt
Browse files

riscv: Pass patch_text() the length in bytes 



patch_text_nosync() already handles an arbitrary length of code, so this
removes a superfluous loop and reduces the number of icache flushes.

Reviewed-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Signed-off-by: default avatarSamuel Holland <samuel.holland@sifive.com>
Reviewed-by: default avatarConor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240327160520.791322-6-samuel.holland@sifive.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 5080ca0f

arch/riscv/include/asm/patch.h

+1 −1
Original line number Diff line number Diff line
@@ -9,7 +9,7 @@ 
int patch_insn_write(void *addr, const void *insn, size_t len);

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

int patch_text_set_nosync(void *addr, u8 c, size_t len);

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

int patch_text(void *addr, u32 *insns, size_t len);



extern int riscv_patch_in_stop_machine;

arch/riscv/kernel/patch.c

+5 −9
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ 
struct patch_insn {

	void *addr;

	u32 *insns;

	int ninsns;

	size_t len;

	atomic_t cpu_count;

};
@@ -239,14 +239,10 @@ NOKPROBE_SYMBOL(patch_text_nosync); 
static int patch_text_cb(void *data)

{

	struct patch_insn *patch = data;

	unsigned long len;

	int i, ret = 0;

	int ret = 0;



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

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

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

			ret = patch_insn_write(patch->addr + i * len, &patch->insns[i], len);

		}

		ret = patch_insn_write(patch->addr, patch->insns, patch->len);

		/*

		 * Make sure the patching store is effective *before* we

		 * increment the counter which releases all waiting CPUs
@@ -266,13 +262,13 @@ static int patch_text_cb(void *data) 
}

NOKPROBE_SYMBOL(patch_text_cb);



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

int patch_text(void *addr, u32 *insns, size_t len)

{

	int ret;

	struct patch_insn patch = {

		.addr = addr,

		.insns = insns,

		.ninsns = ninsns,

		.len = len,

		.cpu_count = ATOMIC_INIT(0),

	};

arch/riscv/kernel/probes/kprobes.c

+10 −8
Original line number Diff line number Diff line
@@ -24,13 +24,13 @@ post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *); 


static void __kprobes arch_prepare_ss_slot(struct kprobe *p)

{

	size_t len = GET_INSN_LENGTH(p->opcode);

	u32 insn = __BUG_INSN_32;

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



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

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



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

	patch_text_nosync(p->ainsn.api.insn + offset, &insn, 1);

	patch_text_nosync(p->ainsn.api.insn, &p->opcode, len);

	patch_text_nosync(p->ainsn.api.insn + len, &insn, GET_INSN_LENGTH(insn));

}



static void __kprobes arch_prepare_simulate(struct kprobe *p)
@@ -107,16 +107,18 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) 
/* install breakpoint in text */

void __kprobes arch_arm_kprobe(struct kprobe *p)

{

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

		   __BUG_INSN_32 : __BUG_INSN_16;

	size_t len = GET_INSN_LENGTH(p->opcode);

	u32 insn = len == 4 ? __BUG_INSN_32 : __BUG_INSN_16;



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

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

}



/* remove breakpoint from text */

void __kprobes arch_disarm_kprobe(struct kprobe *p)

{

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

	size_t len = GET_INSN_LENGTH(p->opcode);



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

}



void __kprobes arch_remove_kprobe(struct kprobe *p)

arch/riscv/net/bpf_jit_comp64.c

+4 −3
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include "bpf_jit.h"



#define RV_FENTRY_NINSNS 2

#define RV_FENTRY_NBYTES (RV_FENTRY_NINSNS * 4)



#define RV_REG_TCC RV_REG_A6

#define RV_REG_TCC_SAVED RV_REG_S6 /* Store A6 in S6 if program do calls */
@@ -672,7 +673,7 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, 
	if (ret)

		return ret;



	if (memcmp(ip, old_insns, RV_FENTRY_NINSNS * 4))

	if (memcmp(ip, old_insns, RV_FENTRY_NBYTES))

		return -EFAULT;



	ret = gen_jump_or_nops(new_addr, ip, new_insns, is_call);
@@ -681,8 +682,8 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, 


	cpus_read_lock();

	mutex_lock(&text_mutex);

	if (memcmp(ip, new_insns, RV_FENTRY_NINSNS * 4))

		ret = patch_text(ip, new_insns, RV_FENTRY_NINSNS);

	if (memcmp(ip, new_insns, RV_FENTRY_NBYTES))

		ret = patch_text(ip, new_insns, RV_FENTRY_NBYTES);

	mutex_unlock(&text_mutex);

	cpus_read_unlock();