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x86, ptdump: Add the functionality to dump an arbitrary pagetable
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With reusing the ->trampoline_pgd page table for mapping EFI regions in
order to use them after having switched to EFI virtual mode, it is very
useful to be able to dump aforementioned page table in dmesg. This adds
that functionality through the walk_pgd_level() interface which can be
called from somewhere else.

The original functionality of dumping to debugfs remains untouched.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
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Borislav Petkov authored and Matt Fleming committed Mar 4, 2014
1 parent 9b7d204 commit ef6bea6
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Showing 2 changed files with 56 additions and 31 deletions.
3 changes: 2 additions & 1 deletion arch/x86/include/asm/pgtable.h
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Original file line number Diff line number Diff line change
Expand Up @@ -15,9 +15,10 @@
: (prot))

#ifndef __ASSEMBLY__

#include <asm/x86_init.h>

void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd);

/*
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..
Expand Down
84 changes: 54 additions & 30 deletions arch/x86/mm/dump_pagetables.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ struct pg_state {
unsigned long start_address;
unsigned long current_address;
const struct addr_marker *marker;
bool to_dmesg;
};

struct addr_marker {
Expand Down Expand Up @@ -88,58 +89,76 @@ static struct addr_marker address_markers[] = {
#define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
#define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)

#define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
({ \
if (to_dmesg) \
printk(KERN_INFO fmt, ##args); \
else \
if (m) \
seq_printf(m, fmt, ##args); \
})

#define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
({ \
if (to_dmesg) \
printk(KERN_CONT fmt, ##args); \
else \
if (m) \
seq_printf(m, fmt, ##args); \
})

/*
* Print a readable form of a pgprot_t to the seq_file
*/
static void printk_prot(struct seq_file *m, pgprot_t prot, int level)
static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
{
pgprotval_t pr = pgprot_val(prot);
static const char * const level_name[] =
{ "cr3", "pgd", "pud", "pmd", "pte" };

if (!pgprot_val(prot)) {
/* Not present */
seq_printf(m, " ");
pt_dump_cont_printf(m, dmsg, " ");
} else {
if (pr & _PAGE_USER)
seq_printf(m, "USR ");
pt_dump_cont_printf(m, dmsg, "USR ");
else
seq_printf(m, " ");
pt_dump_cont_printf(m, dmsg, " ");
if (pr & _PAGE_RW)
seq_printf(m, "RW ");
pt_dump_cont_printf(m, dmsg, "RW ");
else
seq_printf(m, "ro ");
pt_dump_cont_printf(m, dmsg, "ro ");
if (pr & _PAGE_PWT)
seq_printf(m, "PWT ");
pt_dump_cont_printf(m, dmsg, "PWT ");
else
seq_printf(m, " ");
pt_dump_cont_printf(m, dmsg, " ");
if (pr & _PAGE_PCD)
seq_printf(m, "PCD ");
pt_dump_cont_printf(m, dmsg, "PCD ");
else
seq_printf(m, " ");
pt_dump_cont_printf(m, dmsg, " ");

/* Bit 9 has a different meaning on level 3 vs 4 */
if (level <= 3) {
if (pr & _PAGE_PSE)
seq_printf(m, "PSE ");
pt_dump_cont_printf(m, dmsg, "PSE ");
else
seq_printf(m, " ");
pt_dump_cont_printf(m, dmsg, " ");
} else {
if (pr & _PAGE_PAT)
seq_printf(m, "pat ");
pt_dump_cont_printf(m, dmsg, "pat ");
else
seq_printf(m, " ");
pt_dump_cont_printf(m, dmsg, " ");
}
if (pr & _PAGE_GLOBAL)
seq_printf(m, "GLB ");
pt_dump_cont_printf(m, dmsg, "GLB ");
else
seq_printf(m, " ");
pt_dump_cont_printf(m, dmsg, " ");
if (pr & _PAGE_NX)
seq_printf(m, "NX ");
pt_dump_cont_printf(m, dmsg, "NX ");
else
seq_printf(m, "x ");
pt_dump_cont_printf(m, dmsg, "x ");
}
seq_printf(m, "%s\n", level_name[level]);
pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
}

/*
Expand Down Expand Up @@ -178,7 +197,8 @@ static void note_page(struct seq_file *m, struct pg_state *st,
st->current_prot = new_prot;
st->level = level;
st->marker = address_markers;
seq_printf(m, "---[ %s ]---\n", st->marker->name);
pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
st->marker->name);
} else if (prot != cur || level != st->level ||
st->current_address >= st->marker[1].start_address) {
const char *unit = units;
Expand All @@ -188,17 +208,17 @@ static void note_page(struct seq_file *m, struct pg_state *st,
/*
* Now print the actual finished series
*/
seq_printf(m, "0x%0*lx-0x%0*lx ",
width, st->start_address,
width, st->current_address);
pt_dump_seq_printf(m, st->to_dmesg, "0x%0*lx-0x%0*lx ",
width, st->start_address,
width, st->current_address);

delta = (st->current_address - st->start_address) >> 10;
while (!(delta & 1023) && unit[1]) {
delta >>= 10;
unit++;
}
seq_printf(m, "%9lu%c ", delta, *unit);
printk_prot(m, st->current_prot, st->level);
pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ", delta, *unit);
printk_prot(m, st->current_prot, st->level, st->to_dmesg);

/*
* We print markers for special areas of address space,
Expand All @@ -207,7 +227,8 @@ static void note_page(struct seq_file *m, struct pg_state *st,
*/
if (st->current_address >= st->marker[1].start_address) {
st->marker++;
seq_printf(m, "---[ %s ]---\n", st->marker->name);
pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
st->marker->name);
}

st->start_address = st->current_address;
Expand Down Expand Up @@ -296,17 +317,20 @@ static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
#define pgd_none(a) pud_none(__pud(pgd_val(a)))
#endif

static void walk_pgd_level(struct seq_file *m)
void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
{
#ifdef CONFIG_X86_64
pgd_t *start = (pgd_t *) &init_level4_pgt;
#else
pgd_t *start = swapper_pg_dir;
#endif
int i;
struct pg_state st;
struct pg_state st = {};

memset(&st, 0, sizeof(st));
if (pgd) {
start = pgd;
st.to_dmesg = true;
}

for (i = 0; i < PTRS_PER_PGD; i++) {
st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
Expand All @@ -331,7 +355,7 @@ static void walk_pgd_level(struct seq_file *m)

static int ptdump_show(struct seq_file *m, void *v)
{
walk_pgd_level(m);
ptdump_walk_pgd_level(m, NULL);
return 0;
}

Expand Down

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