[GIT PULL] x86 fixes

Ingo Molnar
2018-06-30T08:49:49Z

Linus,

Please pull the latest x86-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-for-linus

# HEAD: d79d0d8ad0cb3d782b41631dfeac8eb05e414bcd x86/mm: Clean up the printk()s in show_fault_oops()

The biggest diffstat comes from self-test updates, plus there's entry code fixes,
5-level paging related fixes, console debug output fixes, plus misc fixes.

out-of-topic modifications in x86-urgent-for-linus:
-----------------------------------------------------
tools/testing/selftests/x86/sigreturn.c# e8a445dea219: selftests/x86/sigreturn: Do
# ec3480205660: selftests/x86/sigreturn/64:

Thanks,

Ingo

------------------>
Andrey Ryabinin (1):
x86/mm: Don't free P4D table when it is folded at runtime

Andy Lutomirski (3):
x86/entry/64/compat: Fix "x86/entry/64/compat: Preserve r8-r11 in int $0x80"
selftests/x86/sigreturn/64: Fix spurious failures on AMD CPUs
selftests/x86/sigreturn: Do minor cleanups

Dmitry Vyukov (2):
x86/mm: Get rid of KERN_CONT in show_fault_oops()
x86/mm: Clean up the printk()s in show_fault_oops()

Jan Beulich (1):
x86/entry/32: Add explicit 'l' instruction suffix

Kirill A. Shutemov (2):
x86/efi: Fix efi_call_phys_epilog() with CONFIG_X86_5LEVEL=y
x86/mm: Drop unneeded __always_inline for p4d page table helpers

arch/x86/entry/entry_32.S | 2 +-
arch/x86/entry/entry_64_compat.S | 16 ++++-----
arch/x86/include/asm/pgalloc.h | 3 ++
arch/x86/include/asm/pgtable.h | 2 +-
arch/x86/include/asm/pgtable_64.h | 4 +--
arch/x86/mm/fault.c | 21 ++++--------
arch/x86/platform/efi/efi_64.c | 4 +--
tools/testing/selftests/x86/sigreturn.c | 59 ++++++++++++++++++++-------------
8 files changed, 60 insertions(+), 51 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 2582881d19ce..c371bfee137a 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -477,7 +477,7 @@ ENTRY(entry_SYSENTER_32)
* whereas POPF does not.)
*/
addl $PT_EFLAGS-PT_DS, %esp /* point esp at pt_regs->flags */
- btr $X86_EFLAGS_IF_BIT, (%esp)
+ btrl $X86_EFLAGS_IF_BIT, (%esp)
popfl

/*
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 9de7f1e1dede..7d0df78db727 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -84,13 +84,13 @@ ENTRY(entry_SYSENTER_compat)
pushq %rdx /* pt_regs->dx */
pushq %rcx /* pt_regs->cx */
pushq $-ENOSYS /* pt_regs->ax */
- pushq %r8 /* pt_regs->r8 */
+ pushq $0 /* pt_regs->r8 = 0 */
xorl %r8d, %r8d /* nospec r8 */
- pushq %r9 /* pt_regs->r9 */
+ pushq $0 /* pt_regs->r9 = 0 */
xorl %r9d, %r9d /* nospec r9 */
- pushq %r10 /* pt_regs->r10 */
+ pushq $0 /* pt_regs->r10 = 0 */
xorl %r10d, %r10d /* nospec r10 */
- pushq %r11 /* pt_regs->r11 */
+ pushq $0 /* pt_regs->r11 = 0 */
xorl %r11d, %r11d /* nospec r11 */
pushq %rbx /* pt_regs->rbx */
xorl %ebx, %ebx /* nospec rbx */
@@ -374,13 +374,13 @@ ENTRY(entry_INT80_compat)
pushq %rcx /* pt_regs->cx */
xorl %ecx, %ecx /* nospec cx */
pushq $-ENOSYS /* pt_regs->ax */
- pushq $0 /* pt_regs->r8 = 0 */
+ pushq %r8 /* pt_regs->r8 */
xorl %r8d, %r8d /* nospec r8 */
- pushq $0 /* pt_regs->r9 = 0 */
+ pushq %r9 /* pt_regs->r9 */
xorl %r9d, %r9d /* nospec r9 */
- pushq $0 /* pt_regs->r10 = 0 */
+ pushq %r10 /* pt_regs->r10*/
xorl %r10d, %r10d /* nospec r10 */
- pushq $0 /* pt_regs->r11 = 0 */
+ pushq %r11 /* pt_regs->r11 */
xorl %r11d, %r11d /* nospec r11 */
pushq %rbx /* pt_regs->rbx */
xorl %ebx, %ebx /* nospec rbx */
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index ada6410fd2ec..fbd578daa66e 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -184,6 +184,9 @@ static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr)

static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
{
+ if (!pgtable_l5_enabled())
+ return;
+
BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));
free_page((unsigned long)p4d);
}
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 99ecde23c3ec..5715647fc4fe 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -898,7 +898,7 @@ static inline unsigned long pgd_page_vaddr(pgd_t pgd)
#define pgd_page(pgd) pfn_to_page(pgd_pfn(pgd))

/* to find an entry in a page-table-directory. */
-static __always_inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address)
+static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address)
{
if (!pgtable_l5_enabled())
return (p4d_t *)pgd;
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 0fdcd21dadbd..3c5385f9a88f 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -216,7 +216,7 @@ static inline pgd_t pti_set_user_pgd(pgd_t *pgdp, pgd_t pgd)
}
#endif

-static __always_inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
+static inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
{
pgd_t pgd;

@@ -230,7 +230,7 @@ static __always_inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
*p4dp = native_make_p4d(native_pgd_val(pgd));
}

-static __always_inline void native_p4d_clear(p4d_t *p4d)
+static inline void native_p4d_clear(p4d_t *p4d)
{
native_set_p4d(p4d, native_make_p4d(0));
}
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 9a84a0d08727..2aafa6ab6103 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -641,11 +641,6 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
return 0;
}

-static const char nx_warning[] = KERN_CRIT
-"kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n";
-static const char smep_warning[] = KERN_CRIT
-"unable to execute userspace code (SMEP?) (uid: %d)\n";
-
static void
show_fault_oops(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
@@ -664,20 +659,18 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
pte = lookup_address_in_pgd(pgd, address, &level);

if (pte && pte_present(*pte) && !pte_exec(*pte))
- printk(nx_warning, from_kuid(&init_user_ns, current_uid()));
+ pr_crit("kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n",
+ from_kuid(&init_user_ns, current_uid()));
if (pte && pte_present(*pte) && pte_exec(*pte) &&
(pgd_flags(*pgd) & _PAGE_USER) &&
(__read_cr4() & X86_CR4_SMEP))
- printk(smep_warning, from_kuid(&init_user_ns, current_uid()));
+ pr_crit("unable to execute userspace code (SMEP?) (uid: %d)\n",
+ from_kuid(&init_user_ns, current_uid()));
}

- printk(KERN_ALERT "BUG: unable to handle kernel ");
- if (address < PAGE_SIZE)
- printk(KERN_CONT "NULL pointer dereference");
- else
- printk(KERN_CONT "paging request");
-
- printk(KERN_CONT " at %px\n", (void *) address);
+ pr_alert("BUG: unable to handle kernel %s at %px\n",
+ address < PAGE_SIZE ? "NULL pointer dereference" : "paging request",
+ (void *)address);

dump_pagetable(address);
}
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index e01f7ceb9e7a..77873ce700ae 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -166,14 +166,14 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
pgd = pgd_offset_k(pgd_idx * PGDIR_SIZE);
set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);

- if (!(pgd_val(*pgd) & _PAGE_PRESENT))
+ if (!pgd_present(*pgd))
continue;

for (i = 0; i < PTRS_PER_P4D; i++) {
p4d = p4d_offset(pgd,
pgd_idx * PGDIR_SIZE + i * P4D_SIZE);

- if (!(p4d_val(*p4d) & _PAGE_PRESENT))
+ if (!p4d_present(*p4d))
continue;

pud = (pud_t *)p4d_page_vaddr(*p4d);
diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c
index 246145b84a12..4d9dc3f2fd70 100644
--- a/tools/testing/selftests/x86/sigreturn.c
+++ b/tools/testing/selftests/x86/sigreturn.c
@@ -610,21 +610,41 @@ static int test_valid_sigreturn(int cs_bits, bool use_16bit_ss, int force_ss)
*/
for (int i = 0; i < NGREG; i++) {
greg_t req = requested_regs[i], res = resulting_regs[i];
+
if (i == REG_TRAPNO || i == REG_IP)
continue; /* don't care */
- if (i == REG_SP) {
- printf("\tSP: %llx -> %llx\n", (unsigned long long)req,
- (unsigned long long)res);

+ if (i == REG_SP) {
/*
- * In many circumstances, the high 32 bits of rsp
- * are zeroed. For example, we could be a real
- * 32-bit program, or we could hit any of a number
- * of poorly-documented IRET or segmented ESP
- * oddities. If this happens, it's okay.
+ * If we were using a 16-bit stack segment, then
+ * the kernel is a bit stuck: IRET only restores
+ * the low 16 bits of ESP/RSP if SS is 16-bit.
+ * The kernel uses a hack to restore bits 31:16,
+ * but that hack doesn't help with bits 63:32.
+ * On Intel CPUs, bits 63:32 end up zeroed, and, on
+ * AMD CPUs, they leak the high bits of the kernel
+ * espfix64 stack pointer. There's very little that
+ * the kernel can do about it.
+ *
+ * Similarly, if we are returning to a 32-bit context,
+ * the CPU will often lose the high 32 bits of RSP.
*/
- if (res == (req & 0xFFFFFFFF))
- continue; /* OK; not expected to work */
+
+ if (res == req)
+ continue;
+
+ if (cs_bits != 64 && ((res ^ req) & 0xFFFFFFFF) == 0) {
+ printf("[NOTE]\tSP: %llx -> %llx\n",
+ (unsigned long long)req,
+ (unsigned long long)res);
+ continue;
+ }
+
+ printf("[FAIL]\tSP mismatch: requested 0x%llx; got 0x%llx\n",
+ (unsigned long long)requested_regs[i],
+ (unsigned long long)resulting_regs[i]);
+ nerrs++;
+ continue;
}

bool ignore_reg = false;
@@ -654,25 +674,18 @@ static int test_valid_sigreturn(int cs_bits, bool use_16bit_ss, int force_ss)
#endif

/* Sanity check on the kernel */
- if (i == REG_CX && requested_regs[i] != resulting_regs[i]) {
+ if (i == REG_CX && req != res) {
printf("[FAIL]\tCX (saved SP) mismatch: requested 0x%llx; got 0x%llx\n",
- (unsigned long long)requested_regs[i],
- (unsigned long long)resulting_regs[i]);
+ (unsigned long long)req,
+ (unsigned long long)res);
nerrs++;
continue;
}

- if (requested_regs[i] != resulting_regs[i] && !ignore_reg) {
- /*
- * SP is particularly interesting here. The
- * usual cause of failures is that we hit the
- * nasty IRET case of returning to a 16-bit SS,
- * in which case bits 16:31 of the *kernel*
- * stack pointer persist in ESP.
- */
+ if (req != res && !ignore_reg) {
printf("[FAIL]\tReg %d mismatch: requested 0x%llx; got 0x%llx\n",
- i, (unsigned long long)requested_regs[i],
- (unsigned long long)resulting_regs[i]);
+ i, (unsigned long long)req,
+ (unsigned long long)res);
nerrs++;
}
}