Re: [patch 08/24] x86/entry: Convert Divide Error to IDTENTRY
From: Alexandre Chartre
Date: Fri Feb 28 2020 - 09:58:53 EST
On 2/25/20 11:16 PM, Thomas Gleixner wrote:
Convert #DE to IDTENTRY:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
No functional change.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/entry/entry_32.S | 7 -------
arch/x86/entry/entry_64.S | 1 -
arch/x86/include/asm/idtentry.h | 3 +++
arch/x86/include/asm/traps.h | 3 ---
arch/x86/kernel/idt.c | 2 +-
arch/x86/kernel/traps.c | 7 ++++++-
arch/x86/xen/enlighten_pv.c | 7 ++++++-
arch/x86/xen/xen-asm_64.S | 2 +-
8 files changed, 17 insertions(+), 15 deletions(-)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -1386,13 +1386,6 @@ SYM_CODE_START(alignment_check)
jmp common_exception
SYM_CODE_END(alignment_check)
-SYM_CODE_START(divide_error)
- ASM_CLAC
- pushl $0 # no error code
- pushl $do_divide_error
- jmp common_exception
-SYM_CODE_END(divide_error)
-
#ifdef CONFIG_X86_MCE
SYM_CODE_START(machine_check)
ASM_CLAC
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1061,7 +1061,6 @@ apicinterrupt IRQ_WORK_VECTOR irq_work
* Exception entry points.
*/
-idtentry X86_TRAP_DE divide_error do_divide_error has_error_code=0
idtentry X86_TRAP_OF overflow do_overflow has_error_code=0
idtentry X86_TRAP_BP int3 do_int3 has_error_code=0
idtentry X86_TRAP_BR bounds do_bounds has_error_code=0
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -76,4 +76,7 @@ static __always_inline void __##func(str
#endif /* __ASSEMBLY__ */
+/* Simple exception entries: */
+DECLARE_IDTENTRY(X86_TRAP_DE, exc_divide_error);
+
I think this macro has a tricky behavior because it will declare C functions
when included in a C file, and define assembly idtentry when included in an
assembly file.
I see your point which is to have a single statement which provides both C
and assembly functions, but this dual behavior is not obvious when reading
the code. Maybe add a comment to explain this behavior?
Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
alex.
#endif
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -11,7 +11,6 @@
#define dotraplinkage __visible
-asmlinkage void divide_error(void);
asmlinkage void debug(void);
asmlinkage void nmi(void);
asmlinkage void int3(void);
@@ -38,7 +37,6 @@ asmlinkage void machine_check(void);
asmlinkage void simd_coprocessor_error(void);
#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
-asmlinkage void xen_divide_error(void);
asmlinkage void xen_xennmi(void);
asmlinkage void xen_xendebug(void);
asmlinkage void xen_int3(void);
@@ -62,7 +60,6 @@ asmlinkage void xen_machine_check(void);
asmlinkage void xen_simd_coprocessor_error(void);
#endif
-dotraplinkage void do_divide_error(struct pt_regs *regs, long error_code);
dotraplinkage void do_debug(struct pt_regs *regs, long error_code);
dotraplinkage void do_nmi(struct pt_regs *regs, long error_code);
dotraplinkage void do_int3(struct pt_regs *regs, long error_code);
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -70,7 +70,7 @@ static const __initconst struct idt_data
* set up TSS.
*/
static const __initconst struct idt_data def_idts[] = {
- INTG(X86_TRAP_DE, divide_error),
+ INTG(X86_TRAP_DE, asm_exc_divide_error),
INTG(X86_TRAP_NMI, nmi),
INTG(X86_TRAP_BR, bounds),
INTG(X86_TRAP_UD, invalid_op),
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -279,6 +279,12 @@ static inline void __user *error_get_tra
return (void __user *)uprobe_get_trap_addr(regs);
}
+DEFINE_IDTENTRY(exc_divide_error)
+{
+ do_error_trap(regs, 0, "divide_error", X86_TRAP_DE, SIGFPE,
+ FPE_INTDIV, error_get_trap_addr(regs));
+}
+
#define IP ((void __user *)uprobe_get_trap_addr(regs))
#define DO_ERROR(trapnr, signr, sicode, addr, str, name) \
dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
@@ -286,7 +292,6 @@ dotraplinkage void do_##name(struct pt_r
do_error_trap(regs, error_code, str, trapnr, signr, sicode, addr); \
}
-DO_ERROR(X86_TRAP_DE, SIGFPE, FPE_INTDIV, IP, "divide error", divide_error)
DO_ERROR(X86_TRAP_OF, SIGSEGV, 0, NULL, "overflow", overflow)
DO_ERROR(X86_TRAP_UD, SIGILL, ILL_ILLOPN, IP, "invalid opcode", invalid_op)
DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, 0, NULL, "coprocessor segment overrun", coprocessor_segment_overrun)
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -602,6 +602,11 @@ struct trap_array_entry {
bool ist_okay;
};
+#define TRAP_ENTRY(func, ist_ok) { \
+ .orig = asm_##func, \
+ .xen = xen_asm_##func, \
+ .ist_okay = ist_ok }
+
static struct trap_array_entry trap_array[] = {
{ debug, xen_xendebug, true },
{ double_fault, xen_double_fault, true },
@@ -615,7 +620,7 @@ static struct trap_array_entry trap_arra
{ entry_INT80_compat, xen_entry_INT80_compat, false },
#endif
{ page_fault, xen_page_fault, false },
- { divide_error, xen_divide_error, false },
+ TRAP_ENTRY(exc_divide_error, false ),
{ bounds, xen_bounds, false },
{ invalid_op, xen_invalid_op, false },
{ device_not_available, xen_device_not_available, false },
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -28,7 +28,7 @@ SYM_CODE_END(xen_\name)
_ASM_NOKPROBE(xen_\name)
.endm
-xen_pv_trap divide_error
+xen_pv_trap asm_exc_divide_error
xen_pv_trap debug
xen_pv_trap xendebug
xen_pv_trap int3