From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
jpoimboe@redhat.com, mark.rutland@arm.com, dvyukov@google.com,
seanjc@google.com, pbonzini@redhat.com, mbenes@suse.cz
Subject: [PATCH v2 08/23] x86,msr: Remove .fixup usage
Date: Wed, 10 Nov 2021 11:01:10 +0100 [thread overview]
Message-ID: <20211110101325.364084212@infradead.org> (raw)
In-Reply-To: 20211110100102.250793167@infradead.org
Rework the MSR accessors to remove .fixup usage. Add two new extable
types (to the 4 already existing msr ones) using the new register
infrastructure to record which register should get the error value.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/extable_fixup_types.h | 23 ++++++-------
arch/x86/include/asm/msr.h | 26 ++++----------
arch/x86/mm/extable.c | 51 +++++++++++++++--------------
3 files changed, 47 insertions(+), 53 deletions(-)
--- a/arch/x86/include/asm/extable_fixup_types.h
+++ b/arch/x86/include/asm/extable_fixup_types.h
@@ -27,17 +27,16 @@
#define EX_TYPE_COPY 4
#define EX_TYPE_CLEAR_FS 5
#define EX_TYPE_FPU_RESTORE 6
-#define EX_TYPE_WRMSR 7
-#define EX_TYPE_RDMSR 8
-#define EX_TYPE_BPF 9
-
-#define EX_TYPE_WRMSR_IN_MCE 10
-#define EX_TYPE_RDMSR_IN_MCE 11
-
-#define EX_TYPE_DEFAULT_MCE_SAFE 12
-#define EX_TYPE_FAULT_MCE_SAFE 13
-
-#define EX_TYPE_POP_ZERO 14
-#define EX_TYPE_IMM_REG 15 /* reg := (long)imm */
+#define EX_TYPE_BPF 7
+#define EX_TYPE_WRMSR 8
+#define EX_TYPE_RDMSR 9
+#define EX_TYPE_WRMSR_SAFE 10 /* reg := -EIO */
+#define EX_TYPE_RDMSR_SAFE 11 /* reg := -EIO */
+#define EX_TYPE_WRMSR_IN_MCE 12
+#define EX_TYPE_RDMSR_IN_MCE 13
+#define EX_TYPE_DEFAULT_MCE_SAFE 14
+#define EX_TYPE_FAULT_MCE_SAFE 15
+#define EX_TYPE_POP_ZERO 16
+#define EX_TYPE_IMM_REG 17 /* reg := (long)imm */
#endif
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -137,17 +137,11 @@ static inline unsigned long long native_
{
DECLARE_ARGS(val, low, high);
- asm volatile("2: rdmsr ; xor %[err],%[err]\n"
- "1:\n\t"
- ".section .fixup,\"ax\"\n\t"
- "3: mov %[fault],%[err]\n\t"
- "xorl %%eax, %%eax\n\t"
- "xorl %%edx, %%edx\n\t"
- "jmp 1b\n\t"
- ".previous\n\t"
- _ASM_EXTABLE(2b, 3b)
+ asm volatile("1: rdmsr ; xor %[err],%[err]\n"
+ "2:\n\t"
+ _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_RDMSR_SAFE, %[err])
: [err] "=r" (*err), EAX_EDX_RET(val, low, high)
- : "c" (msr), [fault] "i" (-EIO));
+ : "c" (msr));
if (tracepoint_enabled(read_msr))
do_trace_read_msr(msr, EAX_EDX_VAL(val, low, high), *err);
return EAX_EDX_VAL(val, low, high);
@@ -169,15 +163,11 @@ native_write_msr_safe(unsigned int msr,
{
int err;
- asm volatile("2: wrmsr ; xor %[err],%[err]\n"
- "1:\n\t"
- ".section .fixup,\"ax\"\n\t"
- "3: mov %[fault],%[err] ; jmp 1b\n\t"
- ".previous\n\t"
- _ASM_EXTABLE(2b, 3b)
+ asm volatile("1: wrmsr ; xor %[err],%[err]\n"
+ "2:\n\t"
+ _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_WRMSR_SAFE, %[err])
: [err] "=a" (err)
- : "c" (msr), "0" (low), "d" (high),
- [fault] "i" (-EIO)
+ : "c" (msr), "0" (low), "d" (high)
: "memory");
if (tracepoint_enabled(write_msr))
do_trace_write_msr(msr, ((u64)high << 32 | low), err);
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -83,28 +83,29 @@ static bool ex_handler_copy(const struct
return ex_handler_fault(fixup, regs, trapnr);
}
-static bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
- struct pt_regs *regs)
+static bool ex_handler_msr(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, bool wrmsr, bool safe, int reg)
{
- if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n",
+ if (!safe && wrmsr &&
+ pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n",
+ (unsigned int)regs->cx, (unsigned int)regs->dx,
+ (unsigned int)regs->ax, regs->ip, (void *)regs->ip))
+ show_stack_regs(regs);
+
+ if (!safe && !wrmsr &&
+ pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n",
(unsigned int)regs->cx, regs->ip, (void *)regs->ip))
show_stack_regs(regs);
- /* Pretend that the read succeeded and returned 0. */
- regs->ax = 0;
- regs->dx = 0;
- return ex_handler_default(fixup, regs);
-}
+ if (!wrmsr) {
+ /* Pretend that the read succeeded and returned 0. */
+ regs->ax = 0;
+ regs->dx = 0;
+ }
-static bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
- struct pt_regs *regs)
-{
- if (pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n",
- (unsigned int)regs->cx, (unsigned int)regs->dx,
- (unsigned int)regs->ax, regs->ip, (void *)regs->ip))
- show_stack_regs(regs);
+ if (safe)
+ *pt_regs_nr(regs, reg) = -EIO;
- /* Pretend that the write succeeded. */
return ex_handler_default(fixup, regs);
}
@@ -186,18 +187,22 @@ int fixup_exception(struct pt_regs *regs
return ex_handler_clear_fs(e, regs);
case EX_TYPE_FPU_RESTORE:
return ex_handler_fprestore(e, regs);
- case EX_TYPE_RDMSR:
- return ex_handler_rdmsr_unsafe(e, regs);
- case EX_TYPE_WRMSR:
- return ex_handler_wrmsr_unsafe(e, regs);
case EX_TYPE_BPF:
return ex_handler_bpf(e, regs);
- case EX_TYPE_RDMSR_IN_MCE:
- ex_handler_msr_mce(regs, false);
- break;
+ case EX_TYPE_WRMSR:
+ return ex_handler_msr(e, regs, true, false, reg);
+ case EX_TYPE_RDMSR:
+ return ex_handler_msr(e, regs, false, false, reg);
+ case EX_TYPE_WRMSR_SAFE:
+ return ex_handler_msr(e, regs, true, true, reg);
+ case EX_TYPE_RDMSR_SAFE:
+ return ex_handler_msr(e, regs, false, true, reg);
case EX_TYPE_WRMSR_IN_MCE:
ex_handler_msr_mce(regs, true);
break;
+ case EX_TYPE_RDMSR_IN_MCE:
+ ex_handler_msr_mce(regs, false);
+ break;
case EX_TYPE_POP_ZERO:
return ex_handler_pop_zero(e, regs);
case EX_TYPE_IMM_REG:
next prev parent reply other threads:[~2021-11-10 10:17 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-10 10:01 [PATCH v2 00/23] x86: Remove anonymous out-of-line fixups Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 01/23] bitfield.h: Fix "type of reg too small for mask" test Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 02/23] x86,mmx_32: Remove .fixup usage Peter Zijlstra
2021-11-15 16:54 ` [PATCH v2.1 02/23] x86/mmx_32: Remove X86_USE_3DNOW Peter Zijlstra
2021-11-16 18:25 ` Borislav Petkov
2021-12-13 9:50 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 03/23] x86,copy_user_64: Remove .fixup usage Peter Zijlstra
2021-11-16 19:04 ` Borislav Petkov
2021-12-13 9:50 ` [tip: x86/core] x86/copy_user_64: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 04/23] x86,copy_mc_64: " Peter Zijlstra
2021-11-17 16:28 ` Borislav Petkov
2021-12-13 9:50 ` [tip: x86/core] x86/copy_mc_64: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 05/23] x86,entry_64: " Peter Zijlstra
2021-11-17 16:29 ` Borislav Petkov
2021-11-19 8:00 ` Lai Jiangshan
2021-12-13 9:50 ` [tip: x86/core] x86/entry_64: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 06/23] x86,entry_32: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/entry_32: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 07/23] x86,extable: Extend extable functionality Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/extable: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` Peter Zijlstra [this message]
2021-12-13 9:50 ` [tip: x86/core] x86/msr: Remove .fixup usage tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 09/23] x86,futex: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/futex: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 10/23] x86,uaccess: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/uaccess: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 11/23] x86,xen: " Peter Zijlstra
2021-11-10 10:35 ` Juergen Gross
2021-11-10 11:00 ` Peter Zijlstra
2021-11-10 12:46 ` Peter Zijlstra
2021-11-10 12:52 ` Juergen Gross
2021-11-10 16:17 ` Peter Zijlstra
2021-11-11 7:20 ` Juergen Gross
2021-11-10 12:45 ` [PATCH v2.1 " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/xen: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 12/23] x86,fpu: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/fpu: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 13/23] x86,segment: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/segment: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 14/23] x86,kvm: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/kvm: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 15/23] x86,vmx: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/vmx: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 16/23] x86,vmx: Provide asm-goto-output vmread Peter Zijlstra
2021-12-13 10:07 ` Peter Zijlstra
2021-12-14 18:44 ` Sean Christopherson
2021-12-14 22:46 ` Peter Zijlstra
2021-12-14 23:07 ` Sean Christopherson
2021-11-10 10:01 ` [PATCH v2 17/23] x86,checksum_32: Remove .fixup usage Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/checksum_32: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 18/23] x86,sgx: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/sgx: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 19/23] x86,usercopy_32: Simplify __copy_user_intel_nocache() Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/usercopy_32: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 20/23] x86,usercopy: Remove .fixup usage Peter Zijlstra
2021-11-11 7:51 ` Josh Poimboeuf
2021-11-11 8:28 ` Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/usercopy: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 21/23] x86,word-at-a-time: " Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] x86/word-at-a-time: " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 22/23] x86: Remove .fixup section Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-11-10 10:01 ` [PATCH v2 23/23] objtool: Remove .fixup handling Peter Zijlstra
2021-12-13 9:50 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-11-11 7:55 ` [PATCH v2 00/23] x86: Remove anonymous out-of-line fixups Josh Poimboeuf
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