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musl/arch/powerpc/pthread_arch.h

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PPC port cleaned up, static linking works well now.
2012-11-09 22:36:55 +00:00
static inline struct pthread *__pthread_self()
{
workaround clang deficiency affecting thread pointer access on powerpc based on patch by Richard Pennington, who initially reported the issue.
2013-12-02 07:45:10 +00:00
#ifdef __clang__
char *tp;
__asm__ __volatile__ ("mr %0, 2" : "=r"(tp) : : );
#else
register char *tp __asm__("r2");
prevent reordering of or1k and powerpc thread pointer loads other archs use asm for the thread pointer load, so making that asm volatile is sufficient to inform the compiler that it has a "side effect" (crashing or giving the wrong result if the thread pointer was not yet initialized) that prevents reordering. however, powerpc and or1k have dedicated general purpose registers for the thread pointer and did not need to use any asm to access it; instead, "local register variables with a specified register" were used. however, there is no specification for ordering constraints on this type of usage, and presumably use of the thread pointer could be reordered across its initialization. to impose an ordering, I have added empty volatile asm blocks that produce the "local register variable with a specified register" as an output constraint.
2015-10-15 16:08:51 +00:00
__asm__ __volatile__ ("" : "=r" (tp) );
workaround clang deficiency affecting thread pointer access on powerpc based on patch by Richard Pennington, who initially reported the issue.
2013-12-02 07:45:10 +00:00
#endif
PPC port cleaned up, static linking works well now.
2012-11-09 22:36:55 +00:00
return (pthread_t)(tp - 0x7000 - sizeof(struct pthread));
}
#define TLS_ABOVE_TP
#define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) + 0x7000)
fix local-dynamic model TLS on mips and powerpc the TLS ABI spec for mips, powerpc, and some other (presently unsupported) RISC archs has the return value of __tls_get_addr offset by +0x8000 and the result of DTPOFF relocations offset by -0x8000. I had previously assumed this part of the ABI was actually just an implementation detail, since the adjustments cancel out. however, when the local dynamic model is used for accessing TLS that's known to be in the same DSO, either of the following may happen: 1. the -0x8000 offset may already be applied to the argument structure passed to __tls_get_addr at ld time, without any opportunity for runtime relocations. 2. __tls_get_addr may be used with a zero offset argument to obtain a base address for the module's TLS, to which the caller then applies immediate offsets for individual objects accessed using the local dynamic model. since the immediate offsets have the -0x8000 adjustment applied to them, the base address they use needs to include the +0x8000 offset. it would be possible, but more complex, to store the pointers in the dtv[] array with the +0x8000 offset pre-applied, to avoid the runtime cost of adding 0x8000 on each call to __tls_get_addr. this change could be made later if measurements show that it would help.
2015-06-25 22:22:00 +00:00
#define DTP_OFFSET 0x8000
PPC port cleaned up, static linking works well now.
2012-11-09 22:36:55 +00:00
// the kernel calls the ip "nip", it's the first saved value after the 32
// GPRs.
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[32]
PPC port cleaned up, static linking works well now.
2012-11-09 22:36:55 +00:00
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 canary_at_end