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riscv: don't use global static vars to store alternative data

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Right now the code uses a global struct to store vendor-ids
and another global variable to store the vendor-patch-function.

There exist specific cases where we'll need to patch the kernel
at an even earlier stage, where trying to write to a static
variable might actually result in hangs.

Also collecting the vendor-information consists of 3 sbi-ecalls
(or csr-reads) which is pretty negligible in the context of
booting a kernel.

So rework the code to not rely on static variables and instead
collect the vendor-information when a round of alternatives is
to be applied.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Link: https://lore.kernel.org/r/20220511192921.2223629-12-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Heiko Stuebner 2022-05-11 21:29:20 +02:00 • committed by Palmer Dabbelt
parent e1026505c1
commit 1745cfafeb
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GPG key ID: EF4CA1502CCBAB41
1 changed files with 24 additions and 27 deletions
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51
arch/riscv/kernel/alternative.c
View file

@ -16,41 +16,35 @@
#include <asm/sbi.h> #include <asm/sbi.h>
#include <asm/csr.h> #include <asm/csr.h>
static struct cpu_manufacturer_info_t { struct cpu_manufacturer_info_t {
unsigned long vendor_id; unsigned long vendor_id;
unsigned long arch_id; unsigned long arch_id;
unsigned long imp_id; unsigned long imp_id;
} cpu_mfr_info; void (*vendor_patch_func)(struct alt_entry *begin, struct alt_entry *end,
unsigned long archid, unsigned long impid,
unsigned int stage);
};
static void (*vendor_patch_func)(struct alt_entry *begin, struct alt_entry *end, static void __init_or_module riscv_fill_cpu_mfr_info(struct cpu_manufacturer_info_t *cpu_mfr_info)
unsigned long archid, unsigned long impid,
unsigned int stage) __initdata_or_module;
static inline void __init riscv_fill_cpu_mfr_info(void)
{ {
#ifdef CONFIG_RISCV_M_MODE #ifdef CONFIG_RISCV_M_MODE
cpu_mfr_info.vendor_id = csr_read(CSR_MVENDORID); cpu_mfr_info->vendor_id = csr_read(CSR_MVENDORID);
cpu_mfr_info.arch_id = csr_read(CSR_MARCHID); cpu_mfr_info->arch_id = csr_read(CSR_MARCHID);
cpu_mfr_info.imp_id = csr_read(CSR_MIMPID); cpu_mfr_info->imp_id = csr_read(CSR_MIMPID);
#else #else
cpu_mfr_info.vendor_id = sbi_get_mvendorid(); cpu_mfr_info->vendor_id = sbi_get_mvendorid();
cpu_mfr_info.arch_id = sbi_get_marchid(); cpu_mfr_info->arch_id = sbi_get_marchid();
cpu_mfr_info.imp_id = sbi_get_mimpid(); cpu_mfr_info->imp_id = sbi_get_mimpid();
#endif #endif
}
static void __init init_alternative(void) switch (cpu_mfr_info->vendor_id) {
{
riscv_fill_cpu_mfr_info();
switch (cpu_mfr_info.vendor_id) {
#ifdef CONFIG_ERRATA_SIFIVE #ifdef CONFIG_ERRATA_SIFIVE
case SIFIVE_VENDOR_ID: case SIFIVE_VENDOR_ID:
vendor_patch_func = sifive_errata_patch_func; cpu_mfr_info->vendor_patch_func = sifive_errata_patch_func;
break; break;
#endif #endif
default: default:
vendor_patch_func = NULL; cpu_mfr_info->vendor_patch_func = NULL;
} }
} }
@ -63,14 +57,19 @@ static void __init_or_module _apply_alternatives(struct alt_entry *begin,
struct alt_entry *end, struct alt_entry *end,
unsigned int stage) unsigned int stage)
{ {
struct cpu_manufacturer_info_t cpu_mfr_info;
riscv_fill_cpu_mfr_info(&cpu_mfr_info);
riscv_cpufeature_patch_func(begin, end, stage); riscv_cpufeature_patch_func(begin, end, stage);
if (!vendor_patch_func) if (!cpu_mfr_info.vendor_patch_func)
return; return;
vendor_patch_func(begin, end, cpu_mfr_info.vendor_patch_func(begin, end,
cpu_mfr_info.arch_id, cpu_mfr_info.imp_id, cpu_mfr_info.arch_id,
stage); cpu_mfr_info.imp_id,
stage);
} }
void __init apply_boot_alternatives(void) void __init apply_boot_alternatives(void)
@ -78,8 +77,6 @@ void __init apply_boot_alternatives(void)
/* If called on non-boot cpu things could go wrong */ /* If called on non-boot cpu things could go wrong */
WARN_ON(smp_processor_id() != 0); WARN_ON(smp_processor_id() != 0);
init_alternative();
_apply_alternatives((struct alt_entry *)__alt_start, _apply_alternatives((struct alt_entry *)__alt_start,
(struct alt_entry *)__alt_end, (struct alt_entry *)__alt_end,
RISCV_ALTERNATIVES_BOOT); RISCV_ALTERNATIVES_BOOT);