From 237c0ee4742b6462cb41cdb3fda1ca55011e4aaf Mon Sep 17 00:00:00 2001 From: Heiko Stuebner Date: Thu, 26 May 2022 22:56:42 +0200 Subject: riscv: drop cpufeature_apply_feature tracking variable The variable was tracking which feature patches got applied but that information was never actually used - and thus resulted in a warning as well. Drop the variable. Reported-by: kernel test robot Signed-off-by: Heiko Stuebner Reviewed-by: Guo Ren Link: https://lore.kernel.org/r/20220526205646.258337-2-heiko@sntech.de Fixes: ff689fd21cb1 ("riscv: add RISC-V Svpbmt extension support") Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/cpufeature.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'arch/riscv/kernel/cpufeature.c') diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index a6f62a6d1edd..12b05ce164bb 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -293,7 +293,6 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin, unsigned int stage) { u32 cpu_req_feature = cpufeature_probe(stage); - u32 cpu_apply_feature = 0; struct alt_entry *alt; u32 tmp; @@ -307,10 +306,8 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin, } tmp = (1U << alt->errata_id); - if (cpu_req_feature & tmp) { + if (cpu_req_feature & tmp) patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len); - cpu_apply_feature |= tmp; - } } } #endif -- cgit v1.2.3 From 1771c8c9e65a20128f93df107353a5f4cb91546a Mon Sep 17 00:00:00 2001 From: Heiko Stuebner Date: Thu, 26 May 2022 22:56:46 +0200 Subject: riscv: remove usage of function-pointers from cpufeatures and t-head errata Having a list of alternatives to check with a per-entry function pointer to a check function is nice style-wise. But in case of early-alternatives it can clash with the non-relocated kernel and the function pointer in the list pointing to a completely wrong location. This isn't an issue with one or two list entries, as in that case the compiler seems to unroll the loop and even usage of the list structure and then only does relative jumps into the check functions based on this. When adding a third entry to either list though, the issue that was hiding there from the beginning is triggered resulting a jump to a memory address that isn't part of the kernel at all. The list of features/erratas only contained an unused name and the pointer to the check function, so an easy solution for the problem is to just unroll the loop in code, dismantle the whole list structure and just call the relevant check functions one by one ourself. For the T-Head errata this includes moving the stage-check inside the check functions. The issue is only relevant for things that might be called for early- alternatives (T-Head and possible future main extensions), so the SiFive erratas were not affected from the beginning, as they got an early return for early-alternatives in the original patchset. Signed-off-by: Heiko Stuebner Tested-by: Samuel Holland Link: https://lore.kernel.org/r/20220526205646.258337-6-heiko@sntech.de Signed-off-by: Palmer Dabbelt --- arch/riscv/errata/thead/errata.c | 38 ++++++++++++-------------------------- arch/riscv/kernel/cpufeature.c | 32 ++++++++++---------------------- 2 files changed, 22 insertions(+), 48 deletions(-) (limited to 'arch/riscv/kernel/cpufeature.c') diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c index e5d75270b99c..b37b6fedd53b 100644 --- a/arch/riscv/errata/thead/errata.c +++ b/arch/riscv/errata/thead/errata.c @@ -14,40 +14,26 @@ #include #include -struct errata_info { - char name[ERRATA_STRING_LENGTH_MAX]; - bool (*check_func)(unsigned long arch_id, unsigned long impid); - unsigned int stage; -}; - -static bool errata_mt_check_func(unsigned long arch_id, unsigned long impid) +static bool errata_probe_pbmt(unsigned int stage, + unsigned long arch_id, unsigned long impid) { if (arch_id != 0 || impid != 0) return false; - return true; -} -static const struct errata_info errata_list[ERRATA_THEAD_NUMBER] = { - { - .name = "memory-types", - .stage = RISCV_ALTERNATIVES_EARLY_BOOT, - .check_func = errata_mt_check_func - }, -}; + if (stage == RISCV_ALTERNATIVES_EARLY_BOOT || + stage == RISCV_ALTERNATIVES_MODULE) + return true; + + return false; +} -static u32 thead_errata_probe(unsigned int stage, unsigned long archid, unsigned long impid) +static u32 thead_errata_probe(unsigned int stage, + unsigned long archid, unsigned long impid) { - const struct errata_info *info; u32 cpu_req_errata = 0; - int idx; - - for (idx = 0; idx < ERRATA_THEAD_NUMBER; idx++) { - info = &errata_list[idx]; - if ((stage == RISCV_ALTERNATIVES_MODULE || - info->stage == stage) && info->check_func(archid, impid)) - cpu_req_errata |= (1U << idx); - } + if (errata_probe_pbmt(stage, archid, impid)) + cpu_req_errata |= (1U << ERRATA_THEAD_PBMT); return cpu_req_errata; } diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 12b05ce164bb..6a40cb8134bd 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -245,12 +245,7 @@ void __init riscv_fill_hwcap(void) } #ifdef CONFIG_RISCV_ALTERNATIVE -struct cpufeature_info { - char name[ERRATA_STRING_LENGTH_MAX]; - bool (*check_func)(unsigned int stage); -}; - -static bool __init_or_module cpufeature_svpbmt_check_func(unsigned int stage) +static bool __init_or_module cpufeature_probe_svpbmt(unsigned int stage) { #ifdef CONFIG_RISCV_ISA_SVPBMT switch (stage) { @@ -264,26 +259,19 @@ static bool __init_or_module cpufeature_svpbmt_check_func(unsigned int stage) return false; } -static const struct cpufeature_info __initdata_or_module -cpufeature_list[CPUFEATURE_NUMBER] = { - { - .name = "svpbmt", - .check_func = cpufeature_svpbmt_check_func - }, -}; - +/* + * Probe presence of individual extensions. + * + * This code may also be executed before kernel relocation, so we cannot use + * addresses generated by the address-of operator as they won't be valid in + * this context. + */ static u32 __init_or_module cpufeature_probe(unsigned int stage) { - const struct cpufeature_info *info; u32 cpu_req_feature = 0; - int idx; - - for (idx = 0; idx < CPUFEATURE_NUMBER; idx++) { - info = &cpufeature_list[idx]; - if (info->check_func(stage)) - cpu_req_feature |= (1U << idx); - } + if (cpufeature_probe_svpbmt(stage)) + cpu_req_feature |= (1U << CPUFEATURE_SVPBMT); return cpu_req_feature; } -- cgit v1.2.3