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RISC-V: Fix IPI/RFENCE hmask on non-monotonic hartid ordering 

If the boot CPU does not have the lowest hartid, "hartid - hbase" can
become negative, leading to an incorrect hmask, causing userspace to
crash with SEGV.  This is observed on e.g. Starlight Beta, where cpuid 1
maps to hartid 0, and cpuid 0 maps to hartid 1.

Fix this by detecting this case, and shifting the accumulated mask and
updating hbase, if possible.

Fixes: 26fb751ca3 ("RISC-V: Do not use cpumask data structure for hartid bitmap")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Tested-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Geert Uytterhoeven 2022-01-31 14:26:22 +01:00 committed by Palmer Dabbelt
parent 2b35d5b7d1
commit 5feef64f4c
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
1 changed files with 39 additions and 18 deletions
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57
arch/riscv/kernel/sbi.c
View File

@ -250,7 +250,7 @@ static void __sbi_set_timer_v02(uint64_t stime_value)
static int __sbi_send_ipi_v02(const struct cpumask *cpu_mask)
{
unsigned long hartid, cpuid, hmask = 0, hbase = 0;
unsigned long hartid, cpuid, hmask = 0, hbase = 0, htop = 0;
struct sbiret ret = {0};
int result;
@ -259,16 +259,27 @@ static int __sbi_send_ipi_v02(const struct cpumask *cpu_mask)
for_each_cpu(cpuid, cpu_mask) {
hartid = cpuid_to_hartid_map(cpuid);
if (hmask && ((hbase + BITS_PER_LONG) <= hartid)) {
ret = sbi_ecall(SBI_EXT_IPI, SBI_EXT_IPI_SEND_IPI,
hmask, hbase, 0, 0, 0, 0);
if (ret.error)
goto ecall_failed;
hmask = 0;
hbase = 0;
if (hmask) {
if (hartid + BITS_PER_LONG <= htop ||
hbase + BITS_PER_LONG <= hartid) {
ret = sbi_ecall(SBI_EXT_IPI,
SBI_EXT_IPI_SEND_IPI, hmask,
hbase, 0, 0, 0, 0);
if (ret.error)
goto ecall_failed;
hmask = 0;
} else if (hartid < hbase) {
/* shift the mask to fit lower hartid */
hmask <<= hbase - hartid;
hbase = hartid;
}
}
if (!hmask)
if (!hmask) {
hbase = hartid;
htop = hartid;
} else if (hartid > htop) {
htop = hartid;
}
hmask |= BIT(hartid - hbase);
}
@ -345,7 +356,7 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
unsigned long start, unsigned long size,
unsigned long arg4, unsigned long arg5)
{
unsigned long hartid, cpuid, hmask = 0, hbase = 0;
unsigned long hartid, cpuid, hmask = 0, hbase = 0, htop = 0;
int result;
if (!cpu_mask || cpumask_empty(cpu_mask))
@ -353,16 +364,26 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
for_each_cpu(cpuid, cpu_mask) {
hartid = cpuid_to_hartid_map(cpuid);
if (hmask && ((hbase + BITS_PER_LONG) <= hartid)) {
result = __sbi_rfence_v02_call(fid, hmask, hbase,
start, size, arg4, arg5);
if (result)
return result;
hmask = 0;
hbase = 0;
if (hmask) {
if (hartid + BITS_PER_LONG <= htop ||
hbase + BITS_PER_LONG <= hartid) {
result = __sbi_rfence_v02_call(fid, hmask,
hbase, start, size, arg4, arg5);
if (result)
return result;
hmask = 0;
} else if (hartid < hbase) {
/* shift the mask to fit lower hartid */
hmask <<= hbase - hartid;
hbase = hartid;
}
}
if (!hmask)
if (!hmask) {
hbase = hartid;
htop = hartid;
} else if (hartid > htop) {
htop = hartid;
}
hmask |= BIT(hartid - hbase);
}