Commit 339d88b5 authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Wen Zhiwei
Browse files

riscv: Fix text patching when IPI are used 

stable inclusion
from stable-v6.6.72
commit 08a2117e83e5f78cd224be8485d90db1110e6517
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IBQN9L

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=08a2117e83e5f78cd224be8485d90db1110e6517



--------------------------------

[ Upstream commit c97bf629963e52b205ed5fbaf151e5bd342f9c63 ]

For now, we use stop_machine() to patch the text and when we use IPIs for
remote icache flushes (which is emitted in patch_text_nosync()), the system
hangs.

So instead, make sure every CPU executes the stop_machine() patching
function and emit a local icache flush there.

Co-developed-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Signed-off-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: default avatarAndrea Parri <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20240229121056.203419-3-alexghiti@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
Stable-dep-of: 13134cc94914 ("riscv: kprobes: Fix incorrect address calculation")
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarWen Zhiwei <wenzhiwei@kylinos.cn>
parent 2db4e6fd

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;
@@ -137,6 +137,42 @@ 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 −4
Original line number Diff line number Diff line
@@ -196,7 +196,7 @@ 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;
@@ -240,16 +240,24 @@ 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);