From 434836c4802e11bddfc98b2addbd4bea952a6fc9 Mon Sep 17 00:00:00 2001
From: "A. Wilcox" <[EMAIL REDACTED]>
Date: Sun, 4 May 2025 15:01:25 -0500
Subject: [PATCH] cpuinfo: Use auxv for AltiVec on Linux if possible
The SIGILL handler is not very reliable and can cause crashes.
Linux provides the CPU's AltiVec support status in getauxval.
(cherry picked from commit 7490471796f287cb284b21ec2643af98e9982b53)
---
src/cpuinfo/SDL_cpuinfo.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/cpuinfo/SDL_cpuinfo.c b/src/cpuinfo/SDL_cpuinfo.c
index 81d1e914ce8cf..a8feec846ff61 100644
--- a/src/cpuinfo/SDL_cpuinfo.c
+++ b/src/cpuinfo/SDL_cpuinfo.c
@@ -115,7 +115,7 @@
#define CPU_CFG2_LSX (1 << 6)
#define CPU_CFG2_LASX (1 << 7)
-#if defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP) && !defined(SDL_PLATFORM_MACOS) && !defined(SDL_PLATFORM_OPENBSD) && !defined(SDL_PLATFORM_FREEBSD)
+#if defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP) && !defined(SDL_PLATFORM_MACOS) && !defined(SDL_PLATFORM_OPENBSD) && !defined(SDL_PLATFORM_FREEBSD) && (defined(SDL_PLATFORM_LINUX) && !defined(HAVE_GETAUXVAL))
/* This is the brute force way of detecting instruction sets...
the idea is borrowed from the libmpeg2 library - thanks!
*/
@@ -344,6 +344,8 @@ static int CPU_haveAltiVec(void)
elf_aux_info(AT_HWCAP, &cpufeatures, sizeof(cpufeatures));
altivec = cpufeatures & PPC_FEATURE_HAS_ALTIVEC;
return altivec;
+#elif defined(SDL_PLATFORM_LINUX) && defined(__powerpc__) && defined(HAVE_GETAUXVAL)
+ altivec = getauxval(AT_HWCAP) & PPC_FEATURE_HAS_ALTIVEC;
#elif defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP)
void (*handler)(int sig);
handler = signal(SIGILL, illegal_instruction);