Unverified Commit 3f452442 authored by Palmer Dabbelt's avatar Palmer Dabbelt
Browse files

Merge patch series "riscv: fix patching with IPI" 

Alexandre Ghiti <alexghiti@rivosinc.com> says:

patch 1 removes a useless memory barrier and patch 2 actually fixes the
issue with IPI in the patching code.

* b4-shazam-merge:
  riscv: Fix text patching when IPI are used
  riscv: Remove superfluous smp_mb()

Link: https://lore.kernel.org/r/20240229121056.203419-1-alexghiti@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parents 63f93a3c c97bf629

arch/riscv/include/asm/patch.h

+1 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#ifndef _ASM_RISCV_PATCH_H

#define _ASM_RISCV_PATCH_H



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);

arch/riscv/kernel/ftrace.c

+40 −4
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/ftrace.h>

#include <linux/uaccess.h>

#include <linux/memory.h>

#include <linux/stop_machine.h>

#include <asm/cacheflush.h>

#include <asm/patch.h>
@@ -75,8 +76,7 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target, 
		make_call_t0(hook_pos, target, call);



	/* Replace the auipc-jalr pair at once. Return -EPERM on write error. */

	if (patch_text_nosync

	    ((void *)hook_pos, enable ? call : nops, MCOUNT_INSN_SIZE))

	if (patch_insn_write((void *)hook_pos, enable ? call : nops, MCOUNT_INSN_SIZE))

		return -EPERM;



	return 0;
@@ -88,7 +88,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 


	make_call_t0(rec->ip, addr, call);



	if (patch_text_nosync((void *)rec->ip, call, MCOUNT_INSN_SIZE))

	if (patch_insn_write((void *)rec->ip, call, MCOUNT_INSN_SIZE))

		return -EPERM;



	return 0;
@@ -99,7 +99,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 
{

	unsigned int nops[2] = {NOP4, NOP4};



	if (patch_text_nosync((void *)rec->ip, nops, MCOUNT_INSN_SIZE))

	if (patch_insn_write((void *)rec->ip, nops, MCOUNT_INSN_SIZE))

		return -EPERM;



	return 0;
@@ -134,6 +134,42 @@ int ftrace_update_ftrace_func(ftrace_func_t func) 


	return ret;

}



struct ftrace_modify_param {

	int command;

	atomic_t cpu_count;

};



static int __ftrace_modify_code(void *data)

{

	struct ftrace_modify_param *param = data;



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

		ftrace_modify_all_code(param->command);

		/*

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

		 * increment the counter which releases all waiting CPUs

		 * by using the release variant of atomic increment. The

		 * release pairs with the call to local_flush_icache_all()

		 * on the waiting CPU.

		 */

		atomic_inc_return_release(&param->cpu_count);

	} else {

		while (atomic_read(&param->cpu_count) <= num_online_cpus())

			cpu_relax();

	}



	local_flush_icache_all();



	return 0;

}



void arch_ftrace_update_code(int command)

{

	struct ftrace_modify_param param = { command, ATOMIC_INIT(0) };



	stop_machine(__ftrace_modify_code, &param, cpu_online_mask);

}

#endif



#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS

arch/riscv/kernel/patch.c

+12 −5
Original line number Diff line number Diff line
@@ -188,7 +188,7 @@ int patch_text_set_nosync(void *addr, u8 c, size_t len) 
}

NOKPROBE_SYMBOL(patch_text_set_nosync);



static int patch_insn_write(void *addr, const void *insn, size_t len)

int patch_insn_write(void *addr, const void *insn, size_t len)

{

	size_t patched = 0;

	size_t size;
@@ -232,16 +232,23 @@ static int patch_text_cb(void *data) 
	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_text_nosync(patch->addr + i * len,

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

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

		}

		atomic_inc(&patch->cpu_count);

		/*

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

		 * increment the counter which releases all waiting CPUs

		 * by using the release variant of atomic increment. The

		 * release pairs with the call to local_flush_icache_all()

		 * on the waiting CPU.

		 */

		atomic_inc_return_release(&patch->cpu_count);

	} else {

		while (atomic_read(&patch->cpu_count) <= num_online_cpus())

			cpu_relax();

		smp_mb();

	}



	local_flush_icache_all();



	return ret;

}

NOKPROBE_SYMBOL(patch_text_cb);