Commit e966ccf8 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Heiko Carstens
Browse files

s390/boot: avoid mapping standby memory 



Commit bb1520d5 ("s390/mm: start kernel with DAT enabled")
doesn't consider online memory holes due to potential memory offlining
and erroneously creates pgtables for stand-by memory, which bear RW+X
attribute and trigger a warning:

RANGE                                 SIZE   STATE REMOVABLE BLOCK
0x0000000000000000-0x0000000c3fffffff  49G  online       yes  0-48
0x0000000c40000000-0x0000000c7fffffff   1G offline              49
0x0000000c80000000-0x0000000fffffffff  14G  online       yes 50-63
0x0000001000000000-0x00000013ffffffff  16G offline           64-79

    s390/mm: Found insecure W+X mapping at address 0xc40000000
    WARNING: CPU: 14 PID: 1 at arch/s390/mm/dump_pagetables.c:142 note_page+0x2cc/0x2d8

Map only online memory ranges which fit within identity mapping limit.

Fixes: bb1520d5 ("s390/mm: start kernel with DAT enabled")
Reviewed-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 2213d44e

arch/s390/boot/boot.h

+1 −1
Original line number Diff line number Diff line
@@ -44,7 +44,7 @@ void print_missing_facilities(void); 
void sclp_early_setup_buffer(void);

void print_pgm_check_info(void);

unsigned long get_random_base(unsigned long safe_addr);

void setup_vmem(unsigned long online_end, unsigned long asce_limit);

void setup_vmem(unsigned long ident_map_size, unsigned long asce_limit);

void __printf(1, 2) decompressor_printk(const char *fmt, ...);

void error(char *m);

arch/s390/boot/startup.c

+1 −3
Original line number Diff line number Diff line
@@ -278,7 +278,6 @@ void startup_kernel(void) 
	unsigned long random_lma;

	unsigned long safe_addr;

	unsigned long asce_limit;

	unsigned long online_end;

	void *img;

	psw_t psw;
@@ -303,7 +302,6 @@ void startup_kernel(void) 
	setup_ident_map_size(detect_memory());

	setup_vmalloc_size();

	asce_limit = setup_kernel_memory_layout();

	online_end = min(get_mem_detect_end(), ident_map_size);



	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_enabled) {

		random_lma = get_random_base(safe_addr);
@@ -335,7 +333,7 @@ void startup_kernel(void) 
	 */

	clear_bss_section();

	handle_relocs(__kaslr_offset);

	setup_vmem(online_end, asce_limit);

	setup_vmem(ident_map_size, asce_limit);

	copy_bootdata();



	if (__kaslr_offset) {

arch/s390/boot/vmem.c

+11 −5
Original line number Diff line number Diff line
@@ -39,7 +39,7 @@ static void boot_check_oom(void) 
		error("out of memory on boot\n");

}



static void pgtable_populate_begin(unsigned long online_end)

static void pgtable_populate_begin(unsigned long ident_map_size)

{

	unsigned long initrd_end;

	unsigned long kernel_end;
@@ -51,7 +51,7 @@ static void pgtable_populate_begin(unsigned long online_end) 
		pgalloc_low = max(pgalloc_low, initrd_end);

	}



	pgalloc_end = round_down(online_end, PAGE_SIZE);

	pgalloc_end = round_down(min(ident_map_size, get_mem_detect_end()), PAGE_SIZE);

	pgalloc_pos = pgalloc_end;



	boot_check_oom();
@@ -247,10 +247,12 @@ static void pgtable_populate_end(void) 
	} while (pgalloc_pos < pgalloc_pos_prev);

}



void setup_vmem(unsigned long online_end, unsigned long asce_limit)

void setup_vmem(unsigned long ident_map_size, unsigned long asce_limit)

{

	unsigned long start, end;

	unsigned long asce_type;

	unsigned long asce_bits;

	int i;



	if (asce_limit == _REGION1_SIZE) {

		asce_type = _REGION2_ENTRY_EMPTY;
@@ -272,9 +274,13 @@ void setup_vmem(unsigned long online_end, unsigned long asce_limit) 
	 * No further pgtable_populate() calls are allowed after the value

	 * of pgalloc_pos finalized with a call to pgtable_populate_end().

	 */

	pgtable_populate_begin(online_end);

	pgtable_populate_begin(ident_map_size);

	pgtable_populate(0, sizeof(struct lowcore), POPULATE_ONE2ONE);

	pgtable_populate(0, online_end, POPULATE_ONE2ONE);

	for_each_mem_detect_block(i, &start, &end) {

		if (start >= ident_map_size)

			break;

		pgtable_populate(start, min(end, ident_map_size), POPULATE_ONE2ONE);

	}

	pgtable_populate(__abs_lowcore, __abs_lowcore + sizeof(struct lowcore),

			 POPULATE_ABS_LOWCORE);

	pgtable_populate(__memcpy_real_area, __memcpy_real_area + PAGE_SIZE,