Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'x86-fpu-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fpu updates from Thomas Gleixner:
"Provide FPU buffer layout in core dumps:
Debuggers have guess the FPU buffer layout in core dumps, which is
error prone. This is because AMD and Intel layouts differ.
To avoid buggy heuristics add a ELF section which describes the buffer
layout which can be retrieved by tools"
* tag 'x86-fpu-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/elf: Add a new FPU buffer layout info to x86 core files
+109
-2
+1
arch/x86/Kconfig
+1
arch/x86/Kconfig
···
107
107
select ARCH_HAS_DEBUG_WX
108
108
select ARCH_HAS_ZONE_DMA_SET if EXPERT
109
109
select ARCH_HAVE_NMI_SAFE_CMPXCHG
110
+
select ARCH_HAVE_EXTRA_ELF_NOTES
110
111
select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
111
112
select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
112
113
select ARCH_MIGHT_HAVE_PC_PARPORT
+16
arch/x86/include/uapi/asm/elf.h
+16
arch/x86/include/uapi/asm/elf.h
···
1
+
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2
+
#ifndef _UAPI_ASM_X86_ELF_H
3
+
#define _UAPI_ASM_X86_ELF_H
4
+
5
+
#include <linux/types.h>
6
+
7
+
struct x86_xfeat_component {
8
+
__u32 type;
9
+
__u32 size;
10
+
__u32 offset;
11
+
__u32 flags;
12
+
} __packed;
13
+
14
+
_Static_assert(sizeof(struct x86_xfeat_component) % 4 == 0, "x86_xfeat_component is not aligned");
15
+
16
+
#endif /* _UAPI_ASM_X86_ELF_H */
+89
arch/x86/kernel/fpu/xstate.c
+89
arch/x86/kernel/fpu/xstate.c
···
13
13
#include <linux/seq_file.h>
14
14
#include <linux/proc_fs.h>
15
15
#include <linux/vmalloc.h>
16
+
#include <linux/coredump.h>
16
17
17
18
#include <asm/fpu/api.h>
18
19
#include <asm/fpu/regset.h>
···
23
22
#include <asm/tlbflush.h>
24
23
#include <asm/prctl.h>
25
24
#include <asm/elf.h>
25
+
26
+
#include <uapi/asm/elf.h>
26
27
27
28
#include "context.h"
28
29
#include "internal.h"
···
1844
1841
return 0;
1845
1842
}
1846
1843
#endif /* CONFIG_PROC_PID_ARCH_STATUS */
1844
+
1845
+
#ifdef CONFIG_COREDUMP
1846
+
static const char owner_name[] = "LINUX";
1847
+
1848
+
/*
1849
+
* Dump type, size, offset and flag values for every xfeature that is present.
1850
+
*/
1851
+
static int dump_xsave_layout_desc(struct coredump_params *cprm)
1852
+
{
1853
+
int num_records = 0;
1854
+
int i;
1855
+
1856
+
for_each_extended_xfeature(i, fpu_user_cfg.max_features) {
1857
+
struct x86_xfeat_component xc = {
1858
+
.type = i,
1859
+
.size = xstate_sizes[i],
1860
+
.offset = xstate_offsets[i],
1861
+
/* reserved for future use */
1862
+
.flags = 0,
1863
+
};
1864
+
1865
+
if (!dump_emit(cprm, &xc, sizeof(xc)))
1866
+
return 0;
1867
+
1868
+
num_records++;
1869
+
}
1870
+
return num_records;
1871
+
}
1872
+
1873
+
static u32 get_xsave_desc_size(void)
1874
+
{
1875
+
u32 cnt = 0;
1876
+
u32 i;
1877
+
1878
+
for_each_extended_xfeature(i, fpu_user_cfg.max_features)
1879
+
cnt++;
1880
+
1881
+
return cnt * (sizeof(struct x86_xfeat_component));
1882
+
}
1883
+
1884
+
int elf_coredump_extra_notes_write(struct coredump_params *cprm)
1885
+
{
1886
+
int num_records = 0;
1887
+
struct elf_note en;
1888
+
1889
+
if (!fpu_user_cfg.max_features)
1890
+
return 0;
1891
+
1892
+
en.n_namesz = sizeof(owner_name);
1893
+
en.n_descsz = get_xsave_desc_size();
1894
+
en.n_type = NT_X86_XSAVE_LAYOUT;
1895
+
1896
+
if (!dump_emit(cprm, &en, sizeof(en)))
1897
+
return 1;
1898
+
if (!dump_emit(cprm, owner_name, en.n_namesz))
1899
+
return 1;
1900
+
if (!dump_align(cprm, 4))
1901
+
return 1;
1902
+
1903
+
num_records = dump_xsave_layout_desc(cprm);
1904
+
if (!num_records)
1905
+
return 1;
1906
+
1907
+
/* Total size should be equal to the number of records */
1908
+
if ((sizeof(struct x86_xfeat_component) * num_records) != en.n_descsz)
1909
+
return 1;
1910
+
1911
+
return 0;
1912
+
}
1913
+
1914
+
int elf_coredump_extra_notes_size(void)
1915
+
{
1916
+
int size;
1917
+
1918
+
if (!fpu_user_cfg.max_features)
1919
+
return 0;
1920
+
1921
+
/* .note header */
1922
+
size = sizeof(struct elf_note);
1923
+
/* Name plus alignment to 4 bytes */
1924
+
size += roundup(sizeof(owner_name), 4);
1925
+
size += get_xsave_desc_size();
1926
+
1927
+
return size;
1928
+
}
1929
+
#endif /* CONFIG_COREDUMP */
+2
-2
fs/binfmt_elf.c
+2
-2
fs/binfmt_elf.c
···
2039
2039
{
2040
2040
size_t sz = info.size;
2041
2041
2042
-
/* For cell spufs */
2042
+
/* For cell spufs and x86 xstate */
2043
2043
sz += elf_coredump_extra_notes_size();
2044
2044
2045
2045
phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL);
···
2103
2103
if (!write_note_info(&info, cprm))
2104
2104
goto end_coredump;
2105
2105
2106
-
/* For cell spufs */
2106
+
/* For cell spufs and x86 xstate */
2107
2107
if (elf_coredump_extra_notes_write(cprm))
2108
2108
goto end_coredump;
2109
2109
+1
include/uapi/linux/elf.h
+1
include/uapi/linux/elf.h
···
411
411
#define NT_X86_XSTATE 0x202 /* x86 extended state using xsave */
412
412
/* Old binutils treats 0x203 as a CET state */
413
413
#define NT_X86_SHSTK 0x204 /* x86 SHSTK state */
414
+
#define NT_X86_XSAVE_LAYOUT 0x205 /* XSAVE layout description */
414
415
#define NT_S390_HIGH_GPRS 0x300 /* s390 upper register halves */
415
416
#define NT_S390_TIMER 0x301 /* s390 timer register */
416
417
#define NT_S390_TODCMP 0x302 /* s390 TOD clock comparator register */