From 61117bfa1b08ca048e6512c0652c568300fedf6a Mon Sep 17 00:00:00 2001 From: Siddhesh Poyarekar Date: Fri, 5 Feb 2021 13:18:58 +0530 Subject: tunables: Simplify TUNABLE_SET interface The TUNABLE_SET interface took a primitive C type argument, which resulted in inconsistent type conversions internally due to incorrect dereferencing of types, especialy on 32-bit architectures. This change simplifies the TUNABLE setting logic along with the interfaces. Now all numeric tunable values are stored as signed numbers in tunable_num_t, which is intmax_t. All calls to set tunables cast the input value to its primitive type and then to tunable_num_t for storage. This relies on gcc-specific (although I suspect other compilers woul also do the same) unsigned to signed integer conversion semantics, i.e. the bit pattern is conserved. The reverse conversion is guaranteed by the standard. --- sysdeps/unix/sysv/linux/aarch64/cpu-features.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'sysdeps/unix/sysv/linux') diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c index fe52b63..db6aa35 100644 --- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c +++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c @@ -104,7 +104,7 @@ init_cpu_features (struct cpu_features *cpu_features) cpu_features->mte_state = (GLRO (dl_hwcap2) & HWCAP2_MTE) ? mte_state : 0; /* If we lack the MTE feature, disable the tunable, since it will otherwise cause instructions that won't run on this CPU to be used. */ - TUNABLE_SET (glibc, mem, tagging, unsigned, cpu_features->mte_state); + TUNABLE_SET (glibc, mem, tagging, cpu_features->mte_state); # endif if (cpu_features->mte_state & 2) -- cgit v1.1