Message ID | 5555CA8C.6030000@arm.com |
---|---|
State | New |
Headers | show |
On 15/05/15 11:29, Szabolcs Nagy wrote: > since > https://sourceware.org/ml/libc-alpha/2014-04/msg00006.html > setcontext etc is no longer tied to the kernel use of ucontext. > > in that patch the ucontext reserved space is not used consistently > with the kernel abi: the d8,d9 pair is saved in the slot of q8. > > this is ok (*context functions work together), but probably not > desirable (ucontexts created by the kernel and getcontext are > subtly different). > > the fix just replaces dN with qN in the save/restore code, which > does a bit more than needed (saves/restores the top half of qN that > is not callee saved), but this should not be an issue (and avoids > having to deal with endianness). > ping. (this changes libc internal abi between *context functions, i assume that should be ok). > (kernel fpsimd context layout: the first 64bit contains 0x210 the fpsimd > context size and 0x46508001 the FPSIMD_MAGIC, the second 64bit is for > fpsr and fpcr, and the rest is the 128bit q0..q31 registers). > > given d8=8.1, d9=9.1,... d15=15.1, the context created by getcontext is > > current: > > (gdb) x/40xg ctx.uc_mcontext.__reserved > 0x410df0 <ctx+464>: 0x0000021046508001 0x0000000000000000 > 0x410e00 <ctx+480>: 0x0000000000000000 0x0000000000000000 > 0x410e10 <ctx+496>: 0x0000000000000000 0x0000000000000000 > 0x410e20 <ctx+512>: 0x0000000000000000 0x0000000000000000 > 0x410e30 <ctx+528>: 0x0000000000000000 0x0000000000000000 > 0x410e40 <ctx+544>: 0x0000000000000000 0x0000000000000000 > 0x410e50 <ctx+560>: 0x0000000000000000 0x0000000000000000 > 0x410e60 <ctx+576>: 0x0000000000000000 0x0000000000000000 > 0x410e70 <ctx+592>: 0x0000000000000000 0x0000000000000000 > 0x410e80 <ctx+608>: 0x4020333333333333 0x4022333333333333 > 0x410e90 <ctx+624>: 0x0000000000000000 0x0000000000000000 > 0x410ea0 <ctx+640>: 0x4024333333333333 0x4026333333333333 > 0x410eb0 <ctx+656>: 0x0000000000000000 0x0000000000000000 > 0x410ec0 <ctx+672>: 0x4028333333333333 0x402a333333333333 > 0x410ed0 <ctx+688>: 0x0000000000000000 0x0000000000000000 > 0x410ee0 <ctx+704>: 0x402c333333333333 0x402e333333333333 > 0x410ef0 <ctx+720>: 0x0000000000000000 0x0000000000000000 > 0x410f00 <ctx+736>: 0x0000000000000000 0x0000000000000000 > 0x410f10 <ctx+752>: 0x0000000000000000 0x0000000000000000 > 0x410f20 <ctx+768>: 0x0000000000000000 0x0000000000000000 > > fixed: > > (gdb) x/40xg ctx.uc_mcontext.__reserved > 0x410d70 <ctx+464>: 0x0000021046508001 0x0000000000000000 > 0x410d80 <ctx+480>: 0x0000000000000000 0x0000000000000000 > 0x410d90 <ctx+496>: 0x0000000000000000 0x0000000000000000 > 0x410da0 <ctx+512>: 0x0000000000000000 0x0000000000000000 > 0x410db0 <ctx+528>: 0x0000000000000000 0x0000000000000000 > 0x410dc0 <ctx+544>: 0x0000000000000000 0x0000000000000000 > 0x410dd0 <ctx+560>: 0x0000000000000000 0x0000000000000000 > 0x410de0 <ctx+576>: 0x0000000000000000 0x0000000000000000 > 0x410df0 <ctx+592>: 0x0000000000000000 0x0000000000000000 > 0x410e00 <ctx+608>: 0x4020333333333333 0x0000000000000000 > 0x410e10 <ctx+624>: 0x4022333333333333 0x0000000000000000 > 0x410e20 <ctx+640>: 0x4024333333333333 0x0000000000000000 > 0x410e30 <ctx+656>: 0x4026333333333333 0x0000000000000000 > 0x410e40 <ctx+672>: 0x4028333333333333 0x0000000000000000 > 0x410e50 <ctx+688>: 0x402a333333333333 0x0000000000000000 > 0x410e60 <ctx+704>: 0x402c333333333333 0x0000000000000000 > 0x410e70 <ctx+720>: 0x402e333333333333 0x0000000000000000 > 0x410e80 <ctx+736>: 0x0000000000000000 0x0000000000000000 > 0x410e90 <ctx+752>: 0x0000000000000000 0x0000000000000000 > 0x410ea0 <ctx+768>: 0x0000000000000000 0x0000000000000000 > > > Changelog: > > 2015-05-15 Szabolcs Nagy <szabolcs.nagy@arm.com> > > * sysdeps/unix/sysv/linux/aarch64/getcontext.S (__getcontext): Use q > registers instead of d ones so the layout is kernel abi compatible. > > * sysdeps/unix/sysv/linux/aarch64/setcontext.S (__setcontext): Likewise. > * sysdeps/unix/sysv/linux/aarch64/swapcontext.S (__swapcontext): > Likewise. >
On 6 July 2015 at 10:49, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote: > On 15/05/15 11:29, Szabolcs Nagy wrote: >> since >> https://sourceware.org/ml/libc-alpha/2014-04/msg00006.html >> setcontext etc is no longer tied to the kernel use of ucontext. >> >> in that patch the ucontext reserved space is not used consistently >> with the kernel abi: the d8,d9 pair is saved in the slot of q8. >> >> this is ok (*context functions work together), but probably not >> desirable (ucontexts created by the kernel and getcontext are >> subtly different). >> >> the fix just replaces dN with qN in the save/restore code, which >> does a bit more than needed (saves/restores the top half of qN that >> is not callee saved), but this should not be an issue (and avoids >> having to deal with endianness). >> > > ping. This is OK. /Marcus
diff --git a/sysdeps/unix/sysv/linux/aarch64/getcontext.S b/sysdeps/unix/sysv/linux/aarch64/getcontext.S index adf8037..b72436f 100644 --- a/sysdeps/unix/sysv/linux/aarch64/getcontext.S +++ b/sysdeps/unix/sysv/linux/aarch64/getcontext.S @@ -69,10 +69,10 @@ ENTRY(__getcontext) /* Fill in the FP SIMD context. */ add x3, x2, #oV0 + 8 * SZVREG - stp d8, d9, [x3], # 2 * SZVREG - stp d10, d11, [x3], # 2 * SZVREG - stp d12, d13, [x3], # 2 * SZVREG - stp d14, d15, [x3], # 2 * SZVREG + stp q8, q9, [x3], # 2 * SZVREG + stp q10, q11, [x3], # 2 * SZVREG + stp q12, q13, [x3], # 2 * SZVREG + stp q14, q15, [x3], # 2 * SZVREG add x3, x2, oFPSR diff --git a/sysdeps/unix/sysv/linux/aarch64/setcontext.S b/sysdeps/unix/sysv/linux/aarch64/setcontext.S index 6dd7836..0bfaafd 100644 --- a/sysdeps/unix/sysv/linux/aarch64/setcontext.S +++ b/sysdeps/unix/sysv/linux/aarch64/setcontext.S @@ -97,10 +97,10 @@ ENTRY (__setcontext) /* Restore the FP SIMD context. */ add x3, x2, #oV0 + 8 * SZVREG - ldp d8, d9, [x3], #2 * SZVREG - ldp d10, d11, [x3], #2 * SZVREG - ldp d12, d13, [x3], #2 * SZVREG - ldp d14, d15, [x3], #2 * SZVREG + ldp q8, q9, [x3], #2 * SZVREG + ldp q10, q11, [x3], #2 * SZVREG + ldp q12, q13, [x3], #2 * SZVREG + ldp q14, q15, [x3], #2 * SZVREG add x3, x2, oFPSR diff --git a/sysdeps/unix/sysv/linux/aarch64/swapcontext.S b/sysdeps/unix/sysv/linux/aarch64/swapcontext.S index f62fc11..05ad8d3 100644 --- a/sysdeps/unix/sysv/linux/aarch64/swapcontext.S +++ b/sysdeps/unix/sysv/linux/aarch64/swapcontext.S @@ -54,10 +54,10 @@ ENTRY(__swapcontext) /* Fill in the FP SIMD context. */ add x3, x2, #oV0 + 8 * SZVREG - stp d8, d9, [x3], #2 * SZVREG - stp d10, d11, [x3], #2 * SZVREG - stp d12, d13, [x3], #2 * SZVREG - stp d14, d15, [x3], #2 * SZVREG + stp q8, q9, [x3], #2 * SZVREG + stp q10, q11, [x3], #2 * SZVREG + stp q12, q13, [x3], #2 * SZVREG + stp q14, q15, [x3], #2 * SZVREG add x3, x2, #oFPSR