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From: James Cowgill <James.Cowgill@imgtec.com>
To: Ralf Baechle <ralf@linux-mips.org>, <linux-mips@linux-mips.org>
Cc: <James.Cowgill@imgtec.com>
Subject: [PATCH] MIPS: avoid BUG warning in arch_check_elf
Date: Tue, 11 Apr 2017 13:51:07 +0100	[thread overview]
Message-ID: <20170411125108.30107-1-James.Cowgill@imgtec.com> (raw)

arch_check_elf contains a usage of current_cpu_data that will call
smp_processor_id() with preemption enabled and therefore triggers a
"BUG: using smp_processor_id() in preemptible" warning when an fpxx
executable is loaded.

As a follow-up to commit b244614a60ab ("MIPS: Avoid a BUG warning during
prctl(PR_SET_FP_MODE, ...)"), apply the same fix to arch_check_elf by
using raw_current_cpu_data instead. The rationale quoted from the previous
commit:

"It is assumed throughout the kernel that if any CPU has an FPU, then
all CPUs would have an FPU as well, so it is safe to perform the check
with preemption enabled - change the code to use raw_ variant of the
check to avoid the warning."

Fixes: 46490b572544 ("MIPS: kernel: elf: Improve the overall ABI and FPU mode checks")
Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
CC: <stable@vger.kernel.org> # 4.0+
---
 arch/mips/kernel/elf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c
index 6430bff21fff..5c429d70e17f 100644
--- a/arch/mips/kernel/elf.c
+++ b/arch/mips/kernel/elf.c
@@ -257,7 +257,7 @@ int arch_check_elf(void *_ehdr, bool has_interpreter, void *_interp_ehdr,
 	else if ((prog_req.fr1 && prog_req.frdefault) ||
 		 (prog_req.single && !prog_req.frdefault))
 		/* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */
-		state->overall_fp_mode = ((current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
+		state->overall_fp_mode = ((raw_current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
 					  cpu_has_mips_r2_r6) ?
 					  FP_FR1 : FP_FR0;
 	else if (prog_req.fr1)
-- 
2.11.0

WARNING: multiple messages have this Message-ID (diff)
From: James Cowgill <James.Cowgill@imgtec.com>
To: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org
Cc: James.Cowgill@imgtec.com
Subject: [PATCH] MIPS: avoid BUG warning in arch_check_elf
Date: Tue, 11 Apr 2017 13:51:07 +0100	[thread overview]
Message-ID: <20170411125108.30107-1-James.Cowgill@imgtec.com> (raw)
Message-ID: <20170411125107.pR_2-ngN4EodJozpT-9ID_bcsuI35Pa5wsawQPBlIWY@z> (raw)

arch_check_elf contains a usage of current_cpu_data that will call
smp_processor_id() with preemption enabled and therefore triggers a
"BUG: using smp_processor_id() in preemptible" warning when an fpxx
executable is loaded.

As a follow-up to commit b244614a60ab ("MIPS: Avoid a BUG warning during
prctl(PR_SET_FP_MODE, ...)"), apply the same fix to arch_check_elf by
using raw_current_cpu_data instead. The rationale quoted from the previous
commit:

"It is assumed throughout the kernel that if any CPU has an FPU, then
all CPUs would have an FPU as well, so it is safe to perform the check
with preemption enabled - change the code to use raw_ variant of the
check to avoid the warning."

Fixes: 46490b572544 ("MIPS: kernel: elf: Improve the overall ABI and FPU mode checks")
Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
CC: <stable@vger.kernel.org> # 4.0+
---
 arch/mips/kernel/elf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c
index 6430bff21fff..5c429d70e17f 100644
--- a/arch/mips/kernel/elf.c
+++ b/arch/mips/kernel/elf.c
@@ -257,7 +257,7 @@ int arch_check_elf(void *_ehdr, bool has_interpreter, void *_interp_ehdr,
 	else if ((prog_req.fr1 && prog_req.frdefault) ||
 		 (prog_req.single && !prog_req.frdefault))
 		/* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */
-		state->overall_fp_mode = ((current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
+		state->overall_fp_mode = ((raw_current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
 					  cpu_has_mips_r2_r6) ?
 					  FP_FR1 : FP_FR0;
 	else if (prog_req.fr1)
-- 
2.11.0

             reply	other threads:[~2017-04-11 12:52 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-11 12:51 James Cowgill [this message]
2017-04-11 12:51 ` [PATCH] MIPS: avoid BUG warning in arch_check_elf James Cowgill
2017-04-12 14:16 ` Ralf Baechle

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