musl/arch/x32/pthread_arch.h

static inline struct pthread *__pthread_self()
{
	struct pthread *self;
	__asm__ ("mov %%fs:0,%0" : "=r" (self) );
	return self;
}

#define MC_PC gregs[REG_RIP]

#define CANARY canary2

#define tls_mod_off_t unsigned long long
import vanilla x86_64 code as x32 2014-01-07 21:43:34 +00:00			`static inline struct pthread *__pthread_self()`
			`{`
			`struct pthread *self;`
make thread-pointer-loading asm non-volatile this will allow the compiler to cache and reuse the result, meaning we no longer have to take care not to load it more than once for the sake of archs where the load may be expensive. depends on commit 1c84c99913bf1cd47b866ed31e665848a0da84a2 for correctness, since otherwise the compiler could hoist loads during stage 3 of dynamic linking before the initial thread-pointer setup. 2018-10-16 18:08:01 +00:00			`__asm__ ("mov %%fs:0,%0" : "=r" (self) );`
import vanilla x86_64 code as x32 2014-01-07 21:43:34 +00:00			`return self;`
			`}`

properly access mcontext_t program counter in cancellation handler using the actual mcontext_t definition rather than an overlaid pointer array both improves correctness/readability and eliminates some ugly hacks for archs with 64-bit registers bit 32-bit program counter. also fix UB due to comparison of pointers not in a common array object. 2015-11-02 17:39:28 +00:00			`#define MC_PC gregs[REG_RIP]`
fix stack protector crashes on x32 & powerpc due to misplaced TLS canary i386, x86_64, x32, and powerpc all use TLS for stack protector canary values in the default stack protector ABI, but the location only matched the ABI on i386 and x86_64. on x32, the expected location for the canary contained the tid, thus producing spurious mismatches (resulting in process termination) upon fork. on powerpc, the expected location contained the stdio_locks list head, so returning from a function after calling flockfile produced spurious mismatches. in both cases, the random canary was not present, and a predictable value was used instead, making the stack protector hardening much less effective than it should be. in the current fix, the thread structure has been expanded to have canary fields at all three possible locations, and archs that use a non-default location must define a macro in pthread_arch.h to choose which location is used. for most archs (which lack TLS canary ABI) the choice does not matter. 2015-05-06 22:37:19 +00:00
			`#define CANARY canary2`
fix crashes in x32 __tls_get_addr x32 has another gratuitous difference to all other archs: it passes an array of 64bit values to __tls_get_addr(). usually it is an array of size_t. 2017-01-13 10:28:46 +00:00
			`#define tls_mod_off_t unsigned long long`