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s390/boot: avoid mapping standby memory

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Commit bb1520d581a3 ("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: bb1520d581a3 ("s390/mm: start kernel with DAT enabled")
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2023-01-23 15:24:17 +01:00 committed by Heiko Carstens
parent 2213d44e14
commit e966ccf836
3 changed files with 13 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/s390/boot/boot.h
View File

@ -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);

4
arch/s390/boot/startup.c
View File

@ -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) {

16
arch/s390/boot/vmem.c
View File

@ -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,