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Rozycki" , Thomas Bogendoerfer , Sasha Levin Subject: [PATCH 6.19 12/86] MIPS: Always record SEGBITS in cpu_data.vmbits Date: Mon, 13 Apr 2026 17:59:19 +0200 Message-ID: <20260413155732.032036688@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155731.568515178@linuxfoundation.org> References: <20260413155731.568515178@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Maciej W. Rozycki commit 8374c2cb83b95b3c92f129fd56527225c20a058c upstream. 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 Signed-off-by: Sasha Levin --- arch/mips/include/asm/cpu-features.h | 1 - arch/mips/include/asm/cpu-info.h | 2 -- arch/mips/include/asm/mipsregs.h | 2 ++ arch/mips/kernel/cpu-probe.c | 13 ++++++++----- arch/mips/kernel/cpu-r3k-probe.c | 2 ++ 5 files changed, 12 insertions(+), 8 deletions(-) diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h index 404390bb87eaf..3f11e5218e6c6 100644 --- a/arch/mips/include/asm/cpu-features.h +++ b/arch/mips/include/asm/cpu-features.h @@ -484,7 +484,6 @@ # endif # ifndef cpu_vmbits # define cpu_vmbits cpu_data[0].vmbits -# define __NEED_VMBITS_PROBE # endif #endif diff --git a/arch/mips/include/asm/cpu-info.h b/arch/mips/include/asm/cpu-info.h index fd60837ce50bc..211b578af6aa0 100644 --- a/arch/mips/include/asm/cpu-info.h +++ b/arch/mips/include/asm/cpu-info.h @@ -80,9 +80,7 @@ struct cpuinfo_mips { int srsets; /* Shadow register sets */ int package;/* physical package number */ unsigned int globalnumber; -#ifdef CONFIG_64BIT int vmbits; /* Virtual memory size in bits */ -#endif void *data; /* Additional data */ unsigned int watch_reg_count; /* Number that exist */ unsigned int watch_reg_use_cnt; /* Usable by ptrace */ diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h index f799c0d723dac..12a095dbf9e2a 100644 --- a/arch/mips/include/asm/mipsregs.h +++ b/arch/mips/include/asm/mipsregs.h @@ -1871,6 +1871,8 @@ do { \ #define read_c0_entryhi() __read_ulong_c0_register($10, 0) #define write_c0_entryhi(val) __write_ulong_c0_register($10, 0, val) +#define read_c0_entryhi_64() __read_64bit_c0_register($10, 0) +#define write_c0_entryhi_64(val) __write_64bit_c0_register($10, 0, val) #define read_c0_guestctl1() __read_32bit_c0_register($10, 4) #define write_c0_guestctl1(val) __write_32bit_c0_register($10, 4, val) diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c index 1e49e05ac8b1c..489612ed9d498 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 0c826f729f752..edcf04de0a6fb 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); } -- 2.53.0