[GIT PULL] x86 fixes

Ingo Molnar
2023-09-17T17:45:09Z

Linus,

Please pull the latest x86/urgent git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2023-09-17

# HEAD: 75b2f7e4c9e0fd750a5a27ca9736d1daa7a3762a x86/purgatory: Remove LTO flags

Misc fixes:

- Fix an UV boot crash,
- Skip spurious ENDBR generation on _THIS_IP_,
- Fix ENDBR use in putuser() asm methods,
- Fix corner case boot crashes on 5-level paging,
- and fix a false positive WARNING on LTO kernels.

Thanks,

Ingo

------------------>
Kirill A. Shutemov (1):
x86/boot/compressed: Reserve more memory for page tables

Peter Zijlstra (2):
x86/ibt: Suppress spurious ENDBR
x86/ibt: Avoid duplicate ENDBR in __put_user_nocheck*()

Song Liu (1):
x86/purgatory: Remove LTO flags

Steve Wahl (1):
x86/platform/uv: Use alternate source for socket to node data

arch/x86/boot/compressed/ident_map_64.c | 8 ++++++
arch/x86/include/asm/boot.h | 47 ++++++++++++++++++++++-----------
arch/x86/include/asm/linkage.h | 8 ++++++
arch/x86/kernel/apic/x2apic_uv_x.c | 11 ++++----
arch/x86/lib/putuser.S | 4 ---
arch/x86/purgatory/Makefile | 4 +++
include/linux/instruction_pointer.h | 5 ++++
7 files changed, 62 insertions(+), 25 deletions(-)

diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
index bcc956c17872..08f93b0401bb 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -59,6 +59,14 @@ static void *alloc_pgt_page(void *context)
return NULL;
}

+ /* Consumed more tables than expected? */
+ if (pages->pgt_buf_offset == BOOT_PGT_SIZE_WARN) {
+ debug_putstr("pgt_buf running low in " __FILE__ "\n");
+ debug_putstr("Need to raise BOOT_PGT_SIZE?\n");
+ debug_putaddr(pages->pgt_buf_offset);
+ debug_putaddr(pages->pgt_buf_size);
+ }
+
entry = pages->pgt_buf + pages->pgt_buf_offset;
pages->pgt_buf_offset += PAGE_SIZE;

diff --git a/arch/x86/include/asm/boot.h b/arch/x86/include/asm/boot.h
index 4ae14339cb8c..b3a7cfb0d99e 100644
--- a/arch/x86/include/asm/boot.h
+++ b/arch/x86/include/asm/boot.h
@@ -40,23 +40,40 @@
#ifdef CONFIG_X86_64
# define BOOT_STACK_SIZE 0x4000

-# define BOOT_INIT_PGT_SIZE (6*4096)
-# ifdef CONFIG_RANDOMIZE_BASE
/*
- * Assuming all cross the 512GB boundary:
- * 1 page for level4
- * (2+2)*4 pages for kernel, param, cmd_line, and randomized kernel
- * 2 pages for first 2M (video RAM: CONFIG_X86_VERBOSE_BOOTUP).
- * Total is 19 pages.
+ * Used by decompressor's startup_32() to allocate page tables for identity
+ * mapping of the 4G of RAM in 4-level paging mode:
+ * - 1 level4 table;
+ * - 1 level3 table;
+ * - 4 level2 table that maps everything with 2M pages;
+ *
+ * The additional level5 table needed for 5-level paging is allocated from
+ * trampoline_32bit memory.
*/
-# ifdef CONFIG_X86_VERBOSE_BOOTUP
-# define BOOT_PGT_SIZE (19*4096)
-# else /* !CONFIG_X86_VERBOSE_BOOTUP */
-# define BOOT_PGT_SIZE (17*4096)
-# endif
-# else /* !CONFIG_RANDOMIZE_BASE */
-# define BOOT_PGT_SIZE BOOT_INIT_PGT_SIZE
-# endif
+# define BOOT_INIT_PGT_SIZE (6*4096)
+
+/*
+ * Total number of page tables kernel_add_identity_map() can allocate,
+ * including page tables consumed by startup_32().
+ *
+ * Worst-case scenario:
+ * - 5-level paging needs 1 level5 table;
+ * - KASLR needs to map kernel, boot_params, cmdline and randomized kernel,
+ * assuming all of them cross 256T boundary:
+ * + 4*2 level4 table;
+ * + 4*2 level3 table;
+ * + 4*2 level2 table;
+ * - X86_VERBOSE_BOOTUP needs to map the first 2M (video RAM):
+ * + 1 level4 table;
+ * + 1 level3 table;
+ * + 1 level2 table;
+ * Total: 28 tables
+ *
+ * Add 4 spare table in case decompressor touches anything beyond what is
+ * accounted above. Warn if it happens.
+ */
+# define BOOT_PGT_SIZE_WARN (28*4096)
+# define BOOT_PGT_SIZE (32*4096)

#else /* !CONFIG_X86_64 */
# define BOOT_STACK_SIZE 0x1000
diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h
index 97a3de7892d3..5ff49fd67732 100644
--- a/arch/x86/include/asm/linkage.h
+++ b/arch/x86/include/asm/linkage.h
@@ -8,6 +8,14 @@
#undef notrace
#define notrace __attribute__((no_instrument_function))

+#ifdef CONFIG_64BIT
+/*
+ * The generic version tends to create spurious ENDBR instructions under
+ * certain conditions.
+ */
+#define _THIS_IP_ ({ unsigned long __here; asm ("lea 0(%%rip), %0" : "=r" (__here)); __here; })
+#endif
+
#ifdef CONFIG_X86_32
#define asmlinkage CPP_ASMLINKAGE __attribute__((regparm(0)))
#endif /* CONFIG_X86_32 */
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index d9f5d7492f83..205cee567629 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -1533,7 +1533,7 @@ static void __init build_socket_tables(void)
{
struct uv_gam_range_entry *gre = uv_gre_table;
int nums, numn, nump;
- int cpu, i, lnid;
+ int i, lnid, apicid;
int minsock = _min_socket;
int maxsock = _max_socket;
int minpnode = _min_pnode;
@@ -1584,15 +1584,14 @@ static void __init build_socket_tables(void)

/* Set socket -> node values: */
lnid = NUMA_NO_NODE;
- for_each_possible_cpu(cpu) {
- int nid = cpu_to_node(cpu);
- int apicid, sockid;
+ for (apicid = 0; apicid < ARRAY_SIZE(__apicid_to_node); apicid++) {
+ int nid = __apicid_to_node[apicid];
+ int sockid;

- if (lnid == nid)
+ if ((nid == NUMA_NO_NODE) || (lnid == nid))
continue;
lnid = nid;

- apicid = per_cpu(x86_cpu_to_apicid, cpu);
sockid = apicid >> uv_cpuid.socketid_shift;

if (_socket_to_node[sockid - minsock] == SOCK_EMPTY)
diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S
index 1451e0c4ae22..235bbda6fc82 100644
--- a/arch/x86/lib/putuser.S
+++ b/arch/x86/lib/putuser.S
@@ -56,7 +56,6 @@ SYM_FUNC_END(__put_user_1)
EXPORT_SYMBOL(__put_user_1)

SYM_FUNC_START(__put_user_nocheck_1)
- ENDBR
ASM_STAC
2: movb %al,(%_ASM_CX)
xor %ecx,%ecx
@@ -76,7 +75,6 @@ SYM_FUNC_END(__put_user_2)
EXPORT_SYMBOL(__put_user_2)

SYM_FUNC_START(__put_user_nocheck_2)
- ENDBR
ASM_STAC
4: movw %ax,(%_ASM_CX)
xor %ecx,%ecx
@@ -96,7 +94,6 @@ SYM_FUNC_END(__put_user_4)
EXPORT_SYMBOL(__put_user_4)

SYM_FUNC_START(__put_user_nocheck_4)
- ENDBR
ASM_STAC
6: movl %eax,(%_ASM_CX)
xor %ecx,%ecx
@@ -119,7 +116,6 @@ SYM_FUNC_END(__put_user_8)
EXPORT_SYMBOL(__put_user_8)

SYM_FUNC_START(__put_user_nocheck_8)
- ENDBR
ASM_STAC
9: mov %_ASM_AX,(%_ASM_CX)
#ifdef CONFIG_X86_32
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index c2a29be35c01..08aa0f25f12a 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -19,6 +19,10 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS -D__NO_FORTIFY
# optimization flags.
KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))

+# When LTO is enabled, llvm emits many text sections, which is not supported
+# by kexec. Remove -flto=* flags.
+KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS))
+
# When linking purgatory.ro with -r unresolved symbols are not checked,
# also link a purgatory.chk binary without -r to check for unresolved symbols.
PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
diff --git a/include/linux/instruction_pointer.h b/include/linux/instruction_pointer.h
index cda1f706eaeb..aa0b3ffea935 100644
--- a/include/linux/instruction_pointer.h
+++ b/include/linux/instruction_pointer.h
@@ -2,7 +2,12 @@
#ifndef _LINUX_INSTRUCTION_POINTER_H
#define _LINUX_INSTRUCTION_POINTER_H

+#include <asm/linkage.h>
+
#define _RET_IP_ (unsigned long)__builtin_return_address(0)
+
+#ifndef _THIS_IP_
#define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; })
+#endif

#endif /* _LINUX_INSTRUCTION_POINTER_H */