[PATCH v2 10/21] MIPS: Avoid unnecessary reservation of exception space

Gregory CLEMENT
2023-11-23T15:27:04Z

From: Jiaxun Yang <jiaxun.yang@flygoat.com>

Nowadays we allocate exception base from memblock for r2_r6,
so we don't need to reverse exception space at the start of
the memory for r2_r6 processors.

For older processors the reservation is moved to traps_init
where we have knowledge of exact size we need. We also add
a sanity check to detect possible overlap with kernel.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
arch/mips/include/asm/traps.h | 1 -
arch/mips/kernel/cpu-probe.c | 5 -----
arch/mips/kernel/cpu-r3k-probe.c | 2 --
arch/mips/kernel/traps.c | 12 +++++++-----
4 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/arch/mips/include/asm/traps.h b/arch/mips/include/asm/traps.h
index 15cde638b4070..d3dddd1c083a9 100644
--- a/arch/mips/include/asm/traps.h
+++ b/arch/mips/include/asm/traps.h
@@ -24,7 +24,6 @@ extern void (*board_ebase_setup)(void);
extern void (*board_cache_error_setup)(void);

extern int register_nmi_notifier(struct notifier_block *nb);
-extern void reserve_exception_space(phys_addr_t addr, unsigned long size);
extern char except_vec_nmi[];

#define VECTORSPACING 0x100 /* for EI/VI mode */
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index b406d8bfb15a3..54e8b0fd4a2ab 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -1570,7 +1570,6 @@ static inline void cpu_probe_broadcom(struct cpuinfo_mips *c, unsigned int cpu)
c->cputype = CPU_BMIPS3300;
__cpu_name[cpu] = "Broadcom BMIPS3300";
set_elf_platform(cpu, "bmips3300");
- reserve_exception_space(0x400, VECTORSPACING * 64);
break;
case PRID_IMP_BMIPS43XX: {
int rev = c->processor_id & PRID_REV_MASK;
@@ -1581,7 +1580,6 @@ static inline void cpu_probe_broadcom(struct cpuinfo_mips *c, unsigned int cpu)
__cpu_name[cpu] = "Broadcom BMIPS4380";
set_elf_platform(cpu, "bmips4380");
c->options |= MIPS_CPU_RIXI;
- reserve_exception_space(0x400, VECTORSPACING * 64);
} else {
c->cputype = CPU_BMIPS4350;
__cpu_name[cpu] = "Broadcom BMIPS4350";
@@ -1598,7 +1596,6 @@ static inline void cpu_probe_broadcom(struct cpuinfo_mips *c, unsigned int cpu)
__cpu_name[cpu] = "Broadcom BMIPS5000";
set_elf_platform(cpu, "bmips5000");
c->options |= MIPS_CPU_ULRI | MIPS_CPU_RIXI;
- reserve_exception_space(0x1000, VECTORSPACING * 64);
break;
}
}
@@ -1996,8 +1993,6 @@ void cpu_probe(void)
if (cpu == 0)
__ua_limit = ~((1ull << cpu_vmbits) - 1);
#endif
-
- reserve_exception_space(0, 0x1000);
}

void cpu_report(void)
diff --git a/arch/mips/kernel/cpu-r3k-probe.c b/arch/mips/kernel/cpu-r3k-probe.c
index be93469c0e0ec..05410b743e571 100644
--- a/arch/mips/kernel/cpu-r3k-probe.c
+++ b/arch/mips/kernel/cpu-r3k-probe.c
@@ -137,8 +137,6 @@ void cpu_probe(void)
cpu_set_fpu_opts(c);
else
cpu_set_nofpu_opts(c);
-
- reserve_exception_space(0, 0x400);
}

void cpu_report(void)
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 651c9ec6265a9..b6e94654f6211 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -2007,10 +2007,6 @@ unsigned long exception_handlers[32];
static unsigned long vi_vecbase;
unsigned long vi_handlers[64];

-void reserve_exception_space(phys_addr_t addr, unsigned long size)
-{
- memblock_reserve(addr, size);
-}

void __init *set_except_vector(int n, void *addr)
{
@@ -2394,7 +2390,13 @@ void __init trap_init(void)
}

if (!cpu_has_mips_r2_r6) {
- ebase = CAC_BASE;
+ ebase_pa = 0x0;
+ ebase = CKSEG0ADDR(ebase_pa);
+
+ if (__pa_symbol(_stext) < (ebase_pa + vec_size))
+ pr_err("Insufficient space for exception vectors\n");
+
+ memblock_reserve(ebase_pa, vec_size);
} else {
vec_size = max(vec_size, PAGE_SIZE);
ebase_pa = memblock_phys_alloc(vec_size, 1 << fls(vec_size));
--
2.42.0