| Message ID | 20230517191436.73636-3-bugaevc@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | Stack setup & misc fixes for x86_64-gnu | expand |
Applied, thanks! Sergey Bugaev via Libc-alpha, le mer. 17 mai 2023 22:14:28 +0300, a ecrit: > The existing two macros, MACHINE_THREAD_STATE_SET_PC and > MACHINE_THREAD_STATE_SET_SP, can be used to set program counter and the > stack pointer registers in a machine-specific thread state structure. > > Useful as it is, this may not be enough to set up the thread to make a > function call, because the machine-specific ABI may impose additional > requirements. In particular, x86_64 ABI requires that upon function > entry, the stack pointer is 8 less than 16-byte aligned (sp & 15 == 8). > > To deal with this, introduce a new macro, > MACHINE_THREAD_STATE_SETUP_CALL (), which sets both stack and > instruction pointers, and also applies any machine-specific requirements > to make a valid function call. The default implementation simply > forwards to MACHINE_THREAD_STATE_SET_PC and MACHINE_THREAD_STATE_SET_SP, > but on x86_64 we additionally align the stack pointer. > > Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> > --- > Any ideas for a better name than PTR_ALIGN_DOWN_8_16? > > sysdeps/mach/thread_state.h | 9 +++++++++ > sysdeps/mach/x86/thread_state.h | 13 +++++++++++++ > 2 files changed, 22 insertions(+) > > diff --git a/sysdeps/mach/thread_state.h b/sysdeps/mach/thread_state.h > index 9fa3d4e1..431aaf82 100644 > --- a/sysdeps/mach/thread_state.h > +++ b/sysdeps/mach/thread_state.h > @@ -38,6 +38,15 @@ > #endif > #endif > > +/* Set up the thread state to call the given function on the given state. > + Dependning on architecture, this may imply more than just setting PC > + and SP. */ > +#ifndef MACHINE_THREAD_STATE_SETUP_CALL > +#define MACHINE_THREAD_STATE_SETUP_CALL(ts, stack, size, func) \ > + (MACHINE_THREAD_STATE_SET_PC (ts, func), \ > + MACHINE_THREAD_STATE_SET_SP (ts, stack, size)) > +#endif > + > /* This copies architecture-specific bits from the current thread to the new > thread state. */ > #ifndef MACHINE_THREAD_STATE_FIX_NEW > diff --git a/sysdeps/mach/x86/thread_state.h b/sysdeps/mach/x86/thread_state.h > index 5be0bec1..8c419515 100644 > --- a/sysdeps/mach/x86/thread_state.h > +++ b/sysdeps/mach/x86/thread_state.h > @@ -20,6 +20,7 @@ > #define _MACH_X86_THREAD_STATE_H 1 > > #include <mach/machine/thread_status.h> > +#include <libc-pointer-arith.h> > > /* This lets the kernel define segments for a new thread. */ > #define MACHINE_NEW_THREAD_STATE_FLAVOR i386_THREAD_STATE > @@ -54,6 +55,18 @@ struct machine_thread_all_state > struct i386_float_state fpu; > }; > > +#ifdef __x86_64__ > +/* We're setting up the stack to perform a function call. On function entry, > + the stack pointer must be 8 bytes less than 16-aligned. */ > +#define PTR_ALIGN_DOWN_8_16(ptr) \ > + ({ uintptr_t __ptr = PTR_ALIGN_DOWN (ptr, 8); \ > + PTR_IS_ALIGNED (__ptr, 16) ? (__ptr - 8) : __ptr; }) > + > +#define MACHINE_THREAD_STATE_SETUP_CALL(ts, stack, size, func) \ > + ((ts)->SP = PTR_ALIGN_DOWN_8_16 ((uintptr_t) (stack) + (size)), \ > + (ts)->PC = (uintptr_t) func) > +#endif > + > #include <sysdeps/mach/thread_state.h> > > #endif /* mach/x86/thread_state.h */ > -- > 2.40.1 >
diff --git a/sysdeps/mach/thread_state.h b/sysdeps/mach/thread_state.h index 9fa3d4e1..431aaf82 100644 --- a/sysdeps/mach/thread_state.h +++ b/sysdeps/mach/thread_state.h @@ -38,6 +38,15 @@ #endif #endif +/* Set up the thread state to call the given function on the given state. + Dependning on architecture, this may imply more than just setting PC + and SP. */ +#ifndef MACHINE_THREAD_STATE_SETUP_CALL +#define MACHINE_THREAD_STATE_SETUP_CALL(ts, stack, size, func) \ + (MACHINE_THREAD_STATE_SET_PC (ts, func), \ + MACHINE_THREAD_STATE_SET_SP (ts, stack, size)) +#endif + /* This copies architecture-specific bits from the current thread to the new thread state. */ #ifndef MACHINE_THREAD_STATE_FIX_NEW diff --git a/sysdeps/mach/x86/thread_state.h b/sysdeps/mach/x86/thread_state.h index 5be0bec1..8c419515 100644 --- a/sysdeps/mach/x86/thread_state.h +++ b/sysdeps/mach/x86/thread_state.h @@ -20,6 +20,7 @@ #define _MACH_X86_THREAD_STATE_H 1 #include <mach/machine/thread_status.h> +#include <libc-pointer-arith.h> /* This lets the kernel define segments for a new thread. */ #define MACHINE_NEW_THREAD_STATE_FLAVOR i386_THREAD_STATE @@ -54,6 +55,18 @@ struct machine_thread_all_state struct i386_float_state fpu; }; +#ifdef __x86_64__ +/* We're setting up the stack to perform a function call. On function entry, + the stack pointer must be 8 bytes less than 16-aligned. */ +#define PTR_ALIGN_DOWN_8_16(ptr) \ + ({ uintptr_t __ptr = PTR_ALIGN_DOWN (ptr, 8); \ + PTR_IS_ALIGNED (__ptr, 16) ? (__ptr - 8) : __ptr; }) + +#define MACHINE_THREAD_STATE_SETUP_CALL(ts, stack, size, func) \ + ((ts)->SP = PTR_ALIGN_DOWN_8_16 ((uintptr_t) (stack) + (size)), \ + (ts)->PC = (uintptr_t) func) +#endif + #include <sysdeps/mach/thread_state.h> #endif /* mach/x86/thread_state.h */
The existing two macros, MACHINE_THREAD_STATE_SET_PC and MACHINE_THREAD_STATE_SET_SP, can be used to set program counter and the stack pointer registers in a machine-specific thread state structure. Useful as it is, this may not be enough to set up the thread to make a function call, because the machine-specific ABI may impose additional requirements. In particular, x86_64 ABI requires that upon function entry, the stack pointer is 8 less than 16-byte aligned (sp & 15 == 8). To deal with this, introduce a new macro, MACHINE_THREAD_STATE_SETUP_CALL (), which sets both stack and instruction pointers, and also applies any machine-specific requirements to make a valid function call. The default implementation simply forwards to MACHINE_THREAD_STATE_SET_PC and MACHINE_THREAD_STATE_SET_SP, but on x86_64 we additionally align the stack pointer. Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> --- Any ideas for a better name than PTR_ALIGN_DOWN_8_16? sysdeps/mach/thread_state.h | 9 +++++++++ sysdeps/mach/x86/thread_state.h | 13 +++++++++++++ 2 files changed, 22 insertions(+)