Commit d83212d5 authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Arnaldo Carvalho de Melo
Browse files

kallsyms, x86: Export addresses of PTI entry trampolines 



Currently, the addresses of PTI entry trampolines are not exported to
user space. Kernel profiling tools need these addresses to identify the
kernel code, so add a symbol and address for each CPU's PTI entry
trampoline.

Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Acked-by: default avatarAndi Kleen <ak@linux.intel.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/1528289651-4113-3-git-send-email-adrian.hunter@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent b9667942

arch/x86/mm/cpu_entry_area.c

+23 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 


#include <linux/spinlock.h>

#include <linux/percpu.h>

#include <linux/kallsyms.h>



#include <asm/cpu_entry_area.h>

#include <asm/pgtable.h>
@@ -150,6 +151,28 @@ static void __init setup_cpu_entry_area(int cpu) 
	percpu_setup_debug_store(cpu);

}



#ifdef CONFIG_X86_64

int arch_get_kallsym(unsigned int symnum, unsigned long *value, char *type,

		     char *name)

{

	unsigned int cpu, ncpu = 0;



	if (symnum >= num_possible_cpus())

		return -EINVAL;



	for_each_possible_cpu(cpu) {

		if (ncpu++ >= symnum)

			break;

	}



	*value = (unsigned long)&get_cpu_entry_area(cpu)->entry_trampoline;

	*type = 't';

	strlcpy(name, "__entry_SYSCALL_64_trampoline", KSYM_NAME_LEN);



	return 0;

}

#endif



static __init void setup_cpu_entry_area_ptes(void)

{

#ifdef CONFIG_X86_32

kernel/kallsyms.c

+27 −1
Original line number Diff line number Diff line
@@ -432,6 +432,7 @@ int sprint_backtrace(char *buffer, unsigned long address) 
/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */

struct kallsym_iter {

	loff_t pos;

	loff_t pos_arch_end;

	loff_t pos_mod_end;

	loff_t pos_ftrace_mod_end;

	unsigned long value;
@@ -443,9 +444,29 @@ struct kallsym_iter { 
	int show_value;

};



int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,

			    char *type, char *name)

{

	return -EINVAL;

}



static int get_ksymbol_arch(struct kallsym_iter *iter)

{

	int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,

				   &iter->value, &iter->type,

				   iter->name);



	if (ret < 0) {

		iter->pos_arch_end = iter->pos;

		return 0;

	}



	return 1;

}



static int get_ksymbol_mod(struct kallsym_iter *iter)

{

	int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,

	int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,

				     &iter->value, &iter->type,

				     iter->name, iter->module_name,

				     &iter->exported);
@@ -501,6 +522,7 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) 
	iter->nameoff = get_symbol_offset(new_pos);

	iter->pos = new_pos;

	if (new_pos == 0) {

		iter->pos_arch_end = 0;

		iter->pos_mod_end = 0;

		iter->pos_ftrace_mod_end = 0;

	}
@@ -515,6 +537,10 @@ static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) 
{

	iter->pos = pos;



	if ((!iter->pos_arch_end || iter->pos_arch_end > pos) &&

	    get_ksymbol_arch(iter))

		return 1;



	if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&

	    get_ksymbol_mod(iter))

		return 1;

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