[PATCH v2 3/4] powerpc/mm: Properly coalesce pages in ptdump
From: Christophe Leroy
Date: Mon Apr 19 2021 - 06:47:41 EST
Commit aaa229529244 ("powerpc/mm: Add physical address to Linux page
table dump") changed range coalescing to only combine ranges that are
both virtually and physically contiguous, in order to avoid erroneous
combination of unrelated mappings in IOREMAP space.
But in the VMALLOC space, mappings almost never have contiguous
physical pages, so the commit mentionned above leads to dumping one
line per page for vmalloc mappings.
Taking into account the vmalloc always leave a gap between two areas,
we never have two mappings dumped as a single combination even if they
have the exact same flags. The only space that may have encountered
such an issue was the early IOREMAP which is not using vmalloc engine.
But previous commits added gaps between early IO mappings, so it is
not an issue anymore.
That commit created some difficulties with KASAN mappings, see
commit cabe8138b23c ("powerpc: dump as a single line areas mapping a
single physical page.") and with huge page, see
commit b00ff6d8c1c3 ("powerpc/ptdump: Properly handle non standard
page size").
So, almost revert commit aaa229529244 to properly coalesce pages
mapped with the same flags as before, only keep the display of the
first physical address of the range, as it can be usefull especially
for IO mappings.
It brings back powerpc at the same level as other architectures and
simplifies the conversion to GENERIC PTDUMP.
With the patch:
---[ kasan shadow mem start ]---
0xf8000000-0xf8ffffff 0x07000000 16M huge rw present dirty accessed
0xf9000000-0xf91fffff 0x01434000 2M r present accessed
0xf9200000-0xf95affff 0x02104000 3776K rw present dirty accessed
0xfef5c000-0xfeffffff 0x01434000 656K r present accessed
---[ kasan shadow mem end ]---
Before:
---[ kasan shadow mem start ]---
0xf8000000-0xf8ffffff 0x07000000 16M huge rw present dirty accessed
0xf9000000-0xf91fffff 0x01434000 16K r present accessed
0xf9200000-0xf9203fff 0x02104000 16K rw present dirty accessed
0xf9204000-0xf9207fff 0x0213c000 16K rw present dirty accessed
0xf9208000-0xf920bfff 0x02174000 16K rw present dirty accessed
0xf920c000-0xf920ffff 0x02188000 16K rw present dirty accessed
0xf9210000-0xf9213fff 0x021dc000 16K rw present dirty accessed
0xf9214000-0xf9217fff 0x02220000 16K rw present dirty accessed
0xf9218000-0xf921bfff 0x023c0000 16K rw present dirty accessed
0xf921c000-0xf921ffff 0x023d4000 16K rw present dirty accessed
0xf9220000-0xf9227fff 0x023ec000 32K rw present dirty accessed
...
0xf93b8000-0xf93e3fff 0x02614000 176K rw present dirty accessed
0xf93e4000-0xf94c3fff 0x027c0000 896K rw present dirty accessed
0xf94c4000-0xf94c7fff 0x0236c000 16K rw present dirty accessed
0xf94c8000-0xf94cbfff 0x041f0000 16K rw present dirty accessed
0xf94cc000-0xf94cffff 0x029c0000 16K rw present dirty accessed
0xf94d0000-0xf94d3fff 0x041ec000 16K rw present dirty accessed
0xf94d4000-0xf94d7fff 0x0407c000 16K rw present dirty accessed
0xf94d8000-0xf94f7fff 0x041c0000 128K rw present dirty accessed
...
0xf95ac000-0xf95affff 0x042b0000 16K rw present dirty accessed
0xfef5c000-0xfeffffff 0x01434000 16K r present accessed
---[ kasan shadow mem end ]---
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Oliver O'Halloran <oohall@xxxxxxxxx>
---
arch/powerpc/mm/ptdump/ptdump.c | 22 +++-------------------
1 file changed, 3 insertions(+), 19 deletions(-)
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index aca354fb670b..5062c58b1e5b 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -58,8 +58,6 @@ struct pg_state {
const struct addr_marker *marker;
unsigned long start_address;
unsigned long start_pa;
- unsigned long last_pa;
- unsigned long page_size;
unsigned int level;
u64 current_flags;
bool check_wx;
@@ -163,8 +161,6 @@ static void dump_flag_info(struct pg_state *st, const struct flag_info
static void dump_addr(struct pg_state *st, unsigned long addr)
{
- unsigned long delta;
-
#ifdef CONFIG_PPC64
#define REG "0x%016lx"
#else
@@ -172,14 +168,8 @@ static void dump_addr(struct pg_state *st, unsigned long addr)
#endif
pt_dump_seq_printf(st->seq, REG "-" REG " ", st->start_address, addr - 1);
- if (st->start_pa == st->last_pa && st->start_address + st->page_size != addr) {
- pt_dump_seq_printf(st->seq, "[" REG "]", st->start_pa);
- delta = st->page_size >> 10;
- } else {
- pt_dump_seq_printf(st->seq, " " REG " ", st->start_pa);
- delta = (addr - st->start_address) >> 10;
- }
- pt_dump_size(st->seq, delta);
+ pt_dump_seq_printf(st->seq, " " REG " ", st->start_pa);
+ pt_dump_size(st->seq, (addr - st->start_address) >> 10);
}
static void note_prot_wx(struct pg_state *st, unsigned long addr)
@@ -208,7 +198,6 @@ static void note_page_update_state(struct pg_state *st, unsigned long addr,
st->current_flags = flag;
st->start_address = addr;
st->start_pa = pa;
- st->page_size = page_size;
while (addr >= st->marker[1].start_address) {
st->marker++;
@@ -220,7 +209,6 @@ static void note_page(struct pg_state *st, unsigned long addr,
unsigned int level, u64 val, unsigned long page_size)
{
u64 flag = val & pg_level[level].mask;
- u64 pa = val & PTE_RPN_MASK;
/* At first no level is set */
if (!st->level) {
@@ -232,12 +220,9 @@ static void note_page(struct pg_state *st, unsigned long addr,
* - we change levels in the tree.
* - the address is in a different section of memory and is thus
* used for a different purpose, regardless of the flags.
- * - the pa of this page is not adjacent to the last inspected page
*/
} else if (flag != st->current_flags || level != st->level ||
- addr >= st->marker[1].start_address ||
- (pa != st->last_pa + st->page_size &&
- (pa != st->start_pa || st->start_pa != st->last_pa))) {
+ addr >= st->marker[1].start_address) {
/* Check the PTE flags */
if (st->current_flags) {
@@ -259,7 +244,6 @@ static void note_page(struct pg_state *st, unsigned long addr,
*/
note_page_update_state(st, addr, level, val, page_size);
}
- st->last_pa = pa;
}
static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
--
2.25.0