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arch/arm64/mmu: fix table discarding code

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First, we have commit 7d27bd0b85 ("arch: arm64: Disable infinite
recursion warning for `discard_table`") that blindly shut up a compiler
warning that did actually highlighted a real bug. Revert that and fix
the bug properly. And yes, mea culpa for having been the first to
approve that commit, or even creating the bug in the first place.

Then let's add proper table usage cound handling for discard_table() to
work properly and avoid leaking table pages.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
This commit is contained in:
Nicolas Pitre 2023-03-06 15:13:19 -05:00 committed by Carles Cufí
parent e72d1bf970
commit abb50e1605
1 changed files with 9 additions and 17 deletions
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26
arch/arm64/core/mmu.c
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@ -427,21 +427,11 @@ static int privatize_page_range(struct arm_mmu_ptables *dst_pt,
return ret;
}
/*
* GCC 12 and above may report a warning about the potential infinite recursion
* in the `discard_table` function.
*/
#if defined(__GNUC__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpragmas"
#pragma GCC diagnostic ignored "-Winfinite-recursion"
#endif
static void discard_table(uint64_t *table, unsigned int level)
{
unsigned int i;
for (i = 0U; Ln_XLAT_NUM_ENTRIES; i++) {
for (i = 0U; i < Ln_XLAT_NUM_ENTRIES; i++) {
if (is_table_desc(table[i], level)) {
table_usage(pte_desc_table(table[i]), -1);
discard_table(pte_desc_table(table[i]), level + 1);
@ -454,10 +444,6 @@ static void discard_table(uint64_t *table, unsigned int level)
free_table(table);
}
#if defined(__GNUC__)
#pragma GCC diagnostic pop
#endif
static int globalize_table(uint64_t *dst_table, uint64_t *src_table,
uintptr_t virt, size_t size, unsigned int level)
{
@ -501,11 +487,17 @@ static int globalize_table(uint64_t *dst_table, uint64_t *src_table,
uint64_t *old_table = is_table_desc(dst_table[i], level) ?
pte_desc_table(dst_table[i]) : NULL;
dst_table[i] = src_table[i];
debug_show_pte(&dst_table[i], level);
if (is_free_desc(dst_table[i])) {
table_usage(dst_table, 1);
}
if (is_free_desc(src_table[i])) {
table_usage(dst_table, -1);
}
if (is_table_desc(src_table[i], level)) {
table_usage(pte_desc_table(src_table[i]), 1);
}
dst_table[i] = src_table[i];
debug_show_pte(&dst_table[i], level);
if (old_table) {
/* we can discard the whole branch */