Unverified Commit 5feef64f authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Palmer Dabbelt
Browse files

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: 26fb751c ("RISC-V: Do not use cpumask data structure for hartid bitmap")
Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: default avatarAtish Patra <atishp@rivosinc.com>
Tested-by: default avatarAtish Patra <atishp@rivosinc.com>
Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 2b35d5b7

arch/riscv/kernel/sbi.c

+39 −18
Original line number Diff line number Diff line
@@ -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 (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;

			hbase = 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 (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;

			hbase = 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);

	}