From 8374c2cb83b95b3c92f129fd56527225c20a058c Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Fri, 27 Mar 2026 18:57:18 +0000 Subject: MIPS: Always record SEGBITS in cpu_data.vmbits With a 32-bit kernel running on 64-bit MIPS hardware the hardcoded value of `cpu_vmbits' only records the size of compatibility useg and does not reflect the size of native xuseg or the complete range of values allowed in the VPN2 field of TLB entries. An upcoming change will need the actual VPN2 value range permitted even in 32-bit kernel configurations, so always include the `vmbits' member in `struct cpuinfo_mips' and probe for SEGBITS when running on 64-bit hardware and resorting to the currently hardcoded value of 31 on 32-bit processors. No functional change for users of `cpu_vmbits'. Signed-off-by: Maciej W. Rozycki Signed-off-by: Thomas Bogendoerfer --- arch/mips/kernel/cpu-probe.c | 13 ++++++++----- arch/mips/kernel/cpu-r3k-probe.c | 2 ++ 2 files changed, 10 insertions(+), 5 deletions(-) (limited to 'arch/mips/kernel') diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c index 1e49e05ac8b1..489612ed9d49 100644 --- a/arch/mips/kernel/cpu-probe.c +++ b/arch/mips/kernel/cpu-probe.c @@ -210,11 +210,14 @@ static inline void set_elf_base_platform(const char *plat) static inline void cpu_probe_vmbits(struct cpuinfo_mips *c) { -#ifdef __NEED_VMBITS_PROBE - write_c0_entryhi(0x3fffffffffffe000ULL); - back_to_back_c0_hazard(); - c->vmbits = fls64(read_c0_entryhi() & 0x3fffffffffffe000ULL); -#endif + int vmbits = 31; + + if (cpu_has_64bits) { + write_c0_entryhi_64(0x3fffffffffffe000ULL); + back_to_back_c0_hazard(); + vmbits = fls64(read_c0_entryhi_64() & 0x3fffffffffffe000ULL); + } + c->vmbits = vmbits; } static void set_isa(struct cpuinfo_mips *c, unsigned int isa) diff --git a/arch/mips/kernel/cpu-r3k-probe.c b/arch/mips/kernel/cpu-r3k-probe.c index 0c826f729f75..edcf04de0a6f 100644 --- a/arch/mips/kernel/cpu-r3k-probe.c +++ b/arch/mips/kernel/cpu-r3k-probe.c @@ -137,6 +137,8 @@ void cpu_probe(void) else cpu_set_nofpu_opts(c); + c->vmbits = 31; + reserve_exception_space(0, 0x400); } -- cgit v1.2.3