mips: Implement the run-time MIPS MSA discovery function correctly
The old implementation of png_have_msa() caused a bus error,
if a word in /proc/cpuinfo was longer than 10 characters.
In the original implementation, `word[10]` was too short, and
`word[i++] = ch` caused a stack smash if the characters between
spaces were more than 10.
And also, fclose(f) should be called before leaving.
For example on loongson ls3a4000 cpu platform:
$ cat /proc/cpuinfo
system type : Generic Loongson64 System
machine : loongson,loongson64g-4core-ls7a
processor : 0
cpu model : ICT Loongson-3 V0.1 FPU V0.1
BogoMIPS : 3594.02
wait instruction : yes
microsecond timers : yes
tlb_entries : 2112
extra interrupt vector : no
hardware watchpoint : no
isa : mips1 mips2 mips3 mips4 mips5 mips32r1 mips32r2 mips64r1 mips64r2
ASEs implemented : vz msa loongson-mmi loongson-cam loongson-ext loongson-ext2
shadow register sets : 1
kscratch registers : 6
package : 0
core : 0
VCED exceptions : not available
VCEI exceptions : not available
processor : 1
cpu model : ICT Loongson-3 V0.1 FPU V0.1
BogoMIPS : 3611.26
wait instruction : yes
microsecond timers : yes
tlb_entries : 2112
extra interrupt vector : no
hardware watchpoint : no
isa : mips1 mips2 mips3 mips4 mips5 mips32r1 mips32r2 mips64r1 mips64r2
ASEs implemented : vz msa loongson-mmi loongson-cam loongson-ext loongson-ext2
shadow register sets : 1
kscratch registers : 6
package : 0
core : 1
VCED exceptions : not available
VCEI exceptions : not available
Co-authored-by: Cosmin Truta <ctruta@gmail.com>
Signed-off-by: Sui Jingfeng <15330273260@189.cn>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
diff --git a/contrib/mips-msa/linux.c b/contrib/mips-msa/linux.c
index 3bac611..cae8ca5 100644
--- a/contrib/mips-msa/linux.c
+++ b/contrib/mips-msa/linux.c
@@ -1,67 +1,55 @@
/* contrib/mips-msa/linux.c
*
- * Copyright (c) 2020 Cosmin Truta
+ * Copyright (c) 2020-2023 Cosmin Truta
* Copyright (c) 2016 Glenn Randers-Pehrson
* Written by Mandar Sahastrabuddhe, 2016.
+ * Updated by Sui Jingfeng, 2021.
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
- * SEE contrib/mips-msa/README before reporting bugs
+ * On Linux, png_have_msa is implemented by reading the pseudo-file
+ * "/proc/self/auxv".
+ *
+ * See contrib/mips-msa/README before reporting bugs.
*
* STATUS: SUPPORTED
* BUG REPORTS: png-mng-implement@sourceforge.net
- *
- * png_have_msa implemented for Linux by reading the widely available
- * pseudo-file /proc/cpuinfo.
- *
- * This code is strict ANSI-C and is probably moderately portable; it does
- * however use <stdio.h> and it assumes that /proc/cpuinfo is never localized.
*/
-#include <stdio.h>
-#include <string.h>
+#include <elf.h>
+#include <fcntl.h>
#include <stdlib.h>
+#include <unistd.h>
static int
png_have_msa(png_structp png_ptr)
{
- FILE *f = fopen("/proc/cpuinfo", "rb");
+ Elf64_auxv_t aux;
+ int fd;
+ int has_msa = 0;
- char *string = "msa";
- char word[10];
-
- if (f != NULL)
+ fd = open("/proc/self/auxv", O_RDONLY);
+ if (fd >= 0)
{
- while(!feof(f))
+ while (read(fd, &aux, sizeof(Elf64_auxv_t)) == sizeof(Elf64_auxv_t))
{
- int ch = fgetc(f);
- static int i = 0;
-
- while(!(ch <= 32))
+ if (aux.a_type == AT_HWCAP)
{
- word[i++] = ch;
- ch = fgetc(f);
+ uint64_t hwcap = aux.a_un.a_val;
+
+ has_msa = (hwcap >> 1) & 1;
+ break;
}
-
- int val = strcmp(string, word);
-
- if (val == 0) {
- fclose(f);
- return 1;
- }
-
- i = 0;
- memset(word, 0, 10);
}
-
- fclose(f);
+ close(fd);
}
#ifdef PNG_WARNINGS_SUPPORTED
else
- png_warning(png_ptr, "/proc/cpuinfo open failed");
+ png_warning(png_ptr, "/proc/self/auxv open failed");
#endif
- return 0;
+
+ return has_msa;
}
